Childhood Obesity: How It’s Prevented and Treated

On By Dr. Scott RennieIn Weight Loss & Metabolic HealthLeave a comment

Childhood obesity is a chronic disease affecting roughly 14.7 million children and adolescents in the United States, and growth charts and BMI percentiles are the least interesting part of it. The American Academy of Pediatrics said as much in its 2023 Clinical Practice Guideline, which reframes obesity as a condition deserving the same urgency and structure we bring to any other chronic disease.

The guideline is built around 13 key action statements plus a set of consensus recommendations. The message running through all of them is that waiting doesn’t work. Early, structured intervention does.

The first shift is consistent screening. Pediatricians should measure height, weight, and BMI annually for every child between 2 and 18. Once BMI reaches the 85th percentile, the number stops being the point and the evaluation begins: dyslipidemia, prediabetes, fatty liver disease, hypertension, sleep apnea. That workup includes history, physical examination, and a careful look at social and environmental context.

For children over 10 with obesity, the guideline recommends a fuller lab evaluation. Fasting glucose or A1c, a lipid panel, liver enzymes, and where indicated a sleep study or a PCOS evaluation in adolescent girls. Depression screening belongs in that set too. Obesity travels with comorbidities, and treating one while ignoring the others misses most of the disease.

Once the diagnosis is made, treatment starts. Not next visit. The model is family-centered and non-stigmatizing, and motivational interviewing sits at the center of it because it lets clinicians surface ambivalence, name barriers, and set goals with families rather than at them.

The cornerstone is Intensive Health Behavior and Lifestyle Treatment. IHBLT is structured and sustained in a way brief counseling never is. The evidence supports at least 26 hours of face-to-face individual or group contact over 3 to 12 months, delivered by a multidisciplinary team of physicians, dietitians, behavioral health providers, and exercise professionals. That threshold is where outcomes start to move, and it applies to children as young as 6.

Nutrition counseling focuses on limiting calorie-dense, nutrient-poor food and increasing fruit, vegetables, and lean protein. Activity goals scale by age, with 60 minutes of moderate-to-vigorous movement daily as the benchmark for school-aged children. Behavioral strategies cover self-monitoring, goal setting, and problem solving. Parental involvement is central rather than optional, and programs that engage parents in the behavior change itself see better outcomes.

For families, this looks nothing like being told to eat better and move more. The intensity and the support structure are what shift the needle.

Not every family can reach a program like that. Geography, insurance, and local capacity all get in the way. The guideline acknowledges it and asks providers to deliver the most comprehensive care available while advocating for expanded community-based IHBLT.

Pharmacologic therapy is the next tier. Adolescents 12 and older may be offered FDA-approved weight-loss medication as an adjunct to health behavior and lifestyle treatment, according to each drug’s indications, risks, and benefits. Twelve is the floor. Medications are adjuncts to behavioral treatment rather than replacements for it.

Metabolic and bariatric surgery is addressed as well. For adolescents 13 and older with severe obesity, defined as BMI at or above 120% of the 95th percentile, the guideline supports referral to a comprehensive pediatric surgical center for evaluation.

The guideline also spends real attention on social determinants. Families dealing with poverty, food insecurity, systemic inequity, or nowhere safe to play are facing barriers that have nothing to do with individual willpower. Effective treatment has to acknowledge that and work on it where it can.

For practicing clinicians the roadmap is short: treat when obesity is identified, use motivational interviewing, refer to or provide IHBLT, manage comorbidities in parallel, and advocate for families against stigma and structural barriers.

Sandra Hassink, who helped lead the work, put the central point plainly when the guideline was released: “There is no evidence that ‘watchful waiting’ or delayed treatment is appropriate for children with obesity.”

Scott Rennie, D.O.

References:

1. Hampl SE, Hassink SG, Skinner AC, et al. Clinical Practice Guideline for the Evaluation and Treatment of Children and Adolescents With Obesity. Pediatrics. 2023;151(2):e2022060640. https://publications.aap.org/pediatrics/article/151/2/e2022060640/190443/

2. Executive Summary: Clinical Practice Guideline for the Evaluation and Treatment of Children and Adolescents With Obesity. Pediatrics. 2023;151(2):e2022060641. https://publications.aap.org/pediatrics/article/151/2/e2022060641/190440/

3. American Academy of Pediatrics. Clinical Practice Guideline for the Evaluation and Treatment of Pediatric Obesity: resources and implementation tools. https://www.aap.org/obesitycpg

Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

What Causes Childhood Obesity? Risks and Next Steps

On By Dr. Scott RennieIn Weight Loss & Metabolic HealthLeave a comment

Physicians are seeing the long-term costs of childhood obesity accumulate in real time. Weight percentiles on a growth chart are the smallest part of the picture. Obesity in children is a chronic disease that touches physical development, emotional health, and metabolic trajectory decades out. The American Academy of Pediatrics has been clear that our role reaches past diagnosis into prevention, intervention, and advocacy, starting early and continuing through a child’s development.

For a long time obesity got reduced to a BMI number. BMI says nothing about the biology underneath. Obesity is a disorder of energy homeostasis. Fat cells expand, inflammation increases, hormones shift, and the central nervous system adapts in ways that make weight regulation genuinely hard. The Obesity Medicine Association describes it as a chronic, neurobehavioral disease, and that framing does useful work. It replaces the story about poor choices with a description of physiology meeting environment.

The seeds go in early. Risk factors show up during pregnancy and infancy: maternal obesity, gestational diabetes, formula feeding, rapid weight gain, early introduction of sugar-sweetened beverages. By preschool, adipose tissue in some children already shows inflammation and insulin resistance (Landgraf et al., Diabetes, 2015). Those changes lay groundwork for chronic disease later.

One of the highest-yield conversations is about what children drink. Families rarely realize how much fruit juice and sweetened beverages contribute. Even 100% fruit juice, which reads as the healthy option, behaves metabolically like soda in quantity. High in sugar, stripped of fiber. The AAP recommends no juice in the first year of life, up to 4 ounces daily for ages 1 to 3, 4 to 6 ounces for ages 4 to 6, and no more than 8 ounces for ages 7 to 18. Water and whole fruit are the better answer.

Sugar-sweetened beverages are worse. Soda, sports drinks, flavored teas, and sweetened waters together make up the single largest source of added sugar in children’s diets. Regular consumption tracks with higher calorie intake, greater risk of type 2 diabetes, and higher odds of obesity. Plenty of families keep soda or juice on the table at meals because it is cheap, familiar, or framed as a treat. Shifting toward water, milk, or unsweetened alternatives is one of the few changes that is both simple and consequential.

Activity is the other side. Children under five should be active throughout the day through running, climbing, and unstructured play. From six through seventeen, the recommendation is at least an hour of moderate-to-vigorous activity daily, including aerobic exercise most days plus muscle- and bone-strengthening activity a few times a week. In practice it is harder than it reads. Parents cite safety, cost, and time. Family walks, bike rides, and dance breaks at home aren’t a substitute for a safe neighborhood, but they build habits that carry.

Sedentary behavior deserves its own attention, and this is where the guidance has moved. The old blanket rule of under two hours of screen time a day has been retired. Current AAP guidance emphasizes content quality, co-viewing, and a Family Media Plan built by the household, with roughly one hour a day of high-quality programming for ages 2 to 5 and no screens before 18 months apart from video chat. For older children the useful questions are what the screen is displacing and whether it has become the only way a child settles. Screen-free zones at meals and before bed remain a practical place for families to start.

Environment shapes outcome beyond individual behavior. Children in food-insecure households face higher obesity risk. Limited budgets push families toward calorie-dense, nutrient-poor food. Chronic stress and disrupted routine make it worse. That overlap is why nutrition counseling has to carry an awareness of social determinants alongside it.

Stigma is its own barrier. Children with obesity face bullying and bias from peers, teachers, and health professionals. Weight stigma increases anxiety, depression, and disordered eating, which worsens the condition rather than motivating change (Pont et al., Pediatrics, 2017). Our language matters here. People-first terms like “a child with obesity” rather than “an obese child” reduce shame and preserve trust.

There are real intervention points at every stage. During pregnancy, supporting healthy maternal weight gain and promoting breastfeeding. In early childhood, limiting sugary drinks, protecting sleep and play, establishing routine. In school-age children and adolescents, motivational interviewing and family-based behavioral programs. Even the EHR earns its keep here, prompting screening, flagging comorbidities, and supporting referrals.

Advocacy belongs in the list. Safe neighborhoods, access to nutritious food, and school meal programs shape children’s health at least as much as counseling does.

Childhood obesity is a systemic problem shaped by biology, environment, and society. Failed parenting doesn’t explain it. Our job is to treat compassionately, intervene early, and advocate for healthier environments, and supporting families rather than blaming them is what changes trajectories.

Scott Rennie, D.O.

References:

1. Landgraf K, et al. Evidence of early alterations in adipose tissue biology and function and its association with obesity-related inflammation and insulin resistance in children. Diabetes. 2015;64(4):1249-1261. https://pubmed.ncbi.nlm.nih.gov/25392242/

2. Pont SJ, et al. Stigma Experienced by Children and Adolescents With Obesity. Pediatrics. 2017;140(6):e20173034. https://pubmed.ncbi.nlm.nih.gov/29158228/

3. Heyman MB, Abrams SA; AAP Section on Gastroenterology, Hepatology, and Nutrition and Committee on Nutrition. Fruit Juice in Infants, Children, and Adolescents: Current Recommendations. Pediatrics. 2017;139(6):e20170967. https://pubmed.ncbi.nlm.nih.gov/28562300/

4. American Academy of Pediatrics. Family Media Plan and screen time guidance. https://www.healthychildren.org/English/fmp/Pages/MediaPlan.aspx

Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

What Brain Scans Show About Appetite and Overeating

On By Dr. Scott RennieIn Weight Loss & Metabolic Health1 Comment

Patients say a version of the same thing constantly: “I know what I should eat, but I still crave the wrong things.” That gap between knowledge and behavior is what pushed researchers toward the brain. Functional MRI has shown that appetite runs on circuits that defend fat mass and respond to food cues, and that willpower is a small part of the story.

For years we leaned on BMI as the working definition of obesity. A BMI over 30 got the label, and the number explained nothing about why weight gain happened or why some patients struggle far more than others. Schwartz and colleagues reframed it in 2017 as “a disorder of energy homeostasis, characterized by the defense of an elevated body fat mass” (Schwartz et al., Endocr Rev, 2017). That definition earns its keep. It says the body is working to hold fat stores high, and that when weight comes off, biology answers with stronger hunger signaling, slower metabolism, and shifted hormones.

The gut-fat-brain conversation sits at the center. Leptin, ghrelin, insulin, GLP-1, and PYY all shape hunger and satiety, and fMRI shows how those signals land. High-calorie food cues light up the amygdala, striatum, medial orbitofrontal cortex, and ventral tegmental area, all reward and craving territory (Schur et al., Int J Obes, 2009; Melhorn et al., Am J Clin Nutr, 2018). After weight loss, that reward response doesn’t fade, which is a large part of why relapse is the rule. Interventions do move it. Leptin replacement, intranasal insulin, GLP-1 agonists, and bariatric surgery all reduce this activation (Holsen et al., Int J Obes, 2018; van Bloemendaal et al., Diabetes, 2014).

One finding deserves more attention than it gets: looking at pictures of calorie-dense food predicts what people actually eat. In studies where participants later chose from a buffet, those with higher reward activation to food images selected more high-fat, high-calorie items. The brain response translated into behavior at the table.

That has treatment implications. Patients with persistent reward-driven responses may get the most from GLP-1 agonists like semaglutide. For others, agents acting on central insulin or leptin signaling may fit better. Bupropion-naltrexone targets reward pathways directly and may suit patients where hedonic eating is the main driver. Obesity is a brain-based condition, and it needs brain-aware treatment.

Inflammation belongs in this picture too. Valdearcos and colleagues showed that rodents on a high-fat diet developed hypothalamic gliosis, an inflammatory response in the brain, before they gained significant weight (Valdearcos et al., Cell Metab, 2017). Human MRI findings line up. Individuals with obesity are more likely to show signs of hypothalamic gliosis (Schur et al., Obesity, 2015; Kreutzer et al., Diabetes, 2017). Inflammation may disrupt appetite regulation early, helping drive the defense of elevated fat mass.

For clinicians, this changes the posture. Blaming patients for “failing” when weight returns misreads the physiology. Their biology is built to resist fat loss. Medications acting on appetite centers belong in long-term care rather than short courses. Diet quality may matter for brain inflammation as well as calorie balance. And as with any other chronic disease, the expectation should be continuous management rather than a one-time fix.

Framing obesity as a chronic brain and inflammatory disease does something useful for the room. It takes stigma out of it. Patients are living with a condition in which the brain defends fat mass through powerful signals, and that framing replaces shame with something we can actually treat.

Scott Rennie, D.O.

References:

1. Schwartz MW, Seeley RJ, Zeltser LM, et al. Obesity Pathogenesis: An Endocrine Society Scientific Statement. Endocr Rev. 2017;38(4):267-296. https://pubmed.ncbi.nlm.nih.gov/28898979/

2. Schur EA, et al. Activation in brain energy regulation and reward centers by food cues varies with choice of visual stimulus. Int J Obes (Lond). 2009;33(6):653-661. https://pubmed.ncbi.nlm.nih.gov/19365394/

3. Melhorn SJ, et al. Am J Clin Nutr. 2018;107(4):574-582.

4. Holsen LM, et al. Int J Obes (Lond). 2018;42(4):785-793.

5. van Bloemendaal L, et al. GLP-1 receptor activation modulates appetite- and reward-related brain areas in humans. Diabetes. 2014;63(12):4186-4196. https://pubmed.ncbi.nlm.nih.gov/25071023/

6. Valdearcos M, et al. Microglial Inflammatory Signaling Orchestrates the Hypothalamic Immune Response to Dietary Excess and Mediates Obesity Susceptibility. Cell Metab. 2017;26(1):185-197.e3. https://pubmed.ncbi.nlm.nih.gov/28683286/

7. Kreutzer C, et al. Hypothalamic Inflammation in Human Obesity Is Mediated by Environmental and Genetic Factors. Diabetes. 2017;66(9):2407-2415. https://pubmed.ncbi.nlm.nih.gov/28576837/

8. Schur EA, et al. Radiologic evidence that hypothalamic gliosis is associated with obesity and insulin resistance in humans. Obesity (Silver Spring). 2015;23(11):2142-2148. https://pubmed.ncbi.nlm.nih.gov/26530930/

Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

Doctor Supervised Weight Loss: What Works Long Term

On By Dr. Scott RennieIn Weight Loss & Metabolic HealthLeave a comment

Telling patients to eat less and move more doesn’t cut it. Obesity is a chronic disease, and progress requires structured, ongoing, individualized care. The hardest part clinically is making sure the weight that comes off is fat rather than muscle.

Losing muscle costs more than strength. It costs independence, recovery capacity, and eventually survival. Older adults and patients with low baseline activity are the most exposed. Poorly managed weight loss produces sarcopenia, the loss of muscle mass and function. Layer excess fat on top and you get sarcopenic obesity, where a patient looks heavy and is functionally weak and metabolically compromised at the same time.

The European Working Group on Sarcopenia in Older People sets out how to catch it early. It starts with loss of strength, measured by grip strength or a chair-stand test. DXA or BIA can confirm low muscle mass. Poor strength plus low mass plus reduced physical performance defines severe sarcopenia. These definitions give us a framework to act before decline becomes permanent (Cruz-Jentoft et al., Age Ageing, 2019).

Muscle mass predicts survival on its own. Appendicular Lean Mass Index, lean tissue in the arms and legs divided by height squared, is a reliable measure, and people in the top quartile carry substantially lower all-cause mortality than those in the lowest, even after adjusting for BMI and comorbidities (Srikanthan & Karlamangla, Am J Med, 2014). Put plainly, a patient with stronger arms and legs has better odds of living longer regardless of what the scale says.

Strength testing matters as much as mass. Low grip strength tracks with higher mortality from cardiovascular disease, cancer, and respiratory illness. Poor lower-body strength, showing up as slower gait speed or difficulty rising from a chair, tracks with frailty, hospitalization, and long-term disability.

Both measures are cheap and fast, and both are underused. Grip strength needs a dynamometer and a hand to put it in, which rules it out of any remote encounter. The 30-second sit-to-stand doesn’t. A hard chair, arms crossed over the chest, as many stands as the patient can complete in thirty seconds, counted by whoever is watching. It works over video as well as it works in a room, and it yields a number worth tracking across visits. One usable functional measure beats a chart full of weights.

Nutrition is the cornerstone of preserving muscle during weight loss. The baseline protein RDA of 0.8 g/kg/day is inadequate for many adults, particularly older patients and anyone in a calorie deficit. The evidence supports closer to 1.2 to 1.6 g/kg/day, and up to 2.0 g/kg/day in some medically supervised cases (Paddon-Jones et al., Am J Clin Nutr, 2015; Bauer et al., J Am Med Dir Assoc, 2013). Spacing intake across meals rather than loading it at dinner sustains muscle protein synthesis better. Whey and casein, soy, eggs, and blended plant sources all work.

Calculating a target in patients with obesity is genuinely awkward. Actual body weight overshoots. Ideal body weight undershoots. Adjusted body weight is the usual compromise, and reasonable clinicians disagree about which to use. For a 5’6″ patient, a target weight around 73 kg at 1.5 g/kg puts the daily goal near 110 grams, which is a number a patient can actually work with.

Exercise has to include both resistance and aerobic work. Resistance training protects and builds lean mass. Aerobic activity improves cardiovascular and metabolic health. A 2022 systematic review and meta-analysis found the combination conferred the greatest mortality risk reduction, and notably found that weight training alone wasn’t associated with lower mortality among people doing no aerobic exercise (Shailendra et al., Am J Prev Med, 2022). For a patient that translates to brisk walking or cycling most days plus two or three weekly strength sessions using bands, weights, or bodyweight.

Think of muscle like a retirement account. Build it and hold it early, so it is there when it is needed. A patient in their seventies who lands in the hospital with pneumonia can lose a large fraction of their reserve to a few days of immobility and poor intake. If the reserve was thin going in, the decline may be permanent, and it shows up later as falls, fractures, and lost independence. Investing ahead of time changes that trajectory.

Medication is a real adjunct, and it has to be paired with strategies that protect lean tissue. GLP-1 receptor agonists produce substantial weight loss, and a meaningful fraction of that loss is lean mass. Adequate protein and resistance training are the mitigation strategies with actual evidence behind them, and body composition deserves monitoring wherever it is available rather than weight alone.

As clinicians, we need to screen past BMI. Ask about physical activity. Get a functional measure. Consider dietary adequacy. Refer to dietitians, physical therapists, or trainers where it helps, and even a single session with a trainer improves safety and confidence with resistance work. Set goals patients can hold: one to two pounds a week of fat loss while protecting muscle.

Obesity treatment is chronic care. The point is helping patients hold strength, mobility, and independence while metabolic health improves, and preserving muscle sits at the center of that.

Scott Rennie, D.O.

References:

1. Cruz-Jentoft AJ, et al. Sarcopenia: revised European consensus on definition and diagnosis. Age Ageing. 2019;48(1):16-31. https://pubmed.ncbi.nlm.nih.gov/30312372/

2. Srikanthan P, Karlamangla AS. Muscle mass index as a predictor of longevity in older adults. Am J Med. 2014;127(6):547-553. https://pubmed.ncbi.nlm.nih.gov/24561114/

3. Paddon-Jones D, et al. Protein and healthy aging. Am J Clin Nutr. 2015;101(6):1339S-1345S. https://pubmed.ncbi.nlm.nih.gov/25926511/

4. Bauer J, et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. J Am Med Dir Assoc. 2013;14(8):542-559. https://pubmed.ncbi.nlm.nih.gov/23867520/

5. Shailendra P, et al. Resistance Training and Mortality Risk: A Systematic Review and Meta-Analysis. Am J Prev Med. 2022;63(2):277-285. https://pubmed.ncbi.nlm.nih.gov/35599175/

Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

What Is MASLD? The New Name for Fatty Liver Disease

On By Dr. Scott RennieIn Weight Loss & Metabolic HealthLeave a comment

Liver disease is showing up more often, and it tracks closely with rising rates of obesity, diabetes, and metabolic syndrome. What many of us trained calling “fatty liver” or NAFLD has been renamed and reframed. The term now is MASLD, metabolic dysfunction-associated steatotic liver disease, and it reflects a better understanding of what actually drives the condition.

Why the change? NAFLD was a definition by exclusion. It told you the disease was not caused by alcohol without saying what it was. It also excluded patients with both alcohol and metabolic drivers, and the word “fatty” carried stigma that most patients felt immediately. In 2023 a multisociety Delphi process involving 236 panelists from 56 countries settled on the new nomenclature. Sixty-six percent of respondents found “fatty” stigmatizing and 61% said the same of “nonalcoholic.” The new definition requires at least one of five cardiometabolic risk factors, and it added MetALD for patients with metabolic dysfunction who also drink significantly (Rinella et al., J Hepatol, 2023).

MASLD is common. Roughly 30% of U.S. adults are affected. Among people with diabetes that figure climbs above 60%, and up to 15% carry advanced fibrosis (Le et al., Clin Mol Hepatol, 2022). Worldwide it is projected to overtake hepatitis C and alcohol as the leading cause of cirrhosis, hepatocellular carcinoma, and liver transplant.

The liver isn’t where most of these patients die. Cardiovascular disease is the leading cause of death in MASLD. The same inflammatory and metabolic pathways that damage the liver drive atherosclerosis. Diabetes worsens MASLD and MASLD worsens diabetes. The relationship runs in both directions.

One point matters more than any other: liver enzymes are a poor marker of severity. Normal ALT and AST are entirely compatible with advanced fibrosis. Fibrosis stage is what predicts progression, complications, and mortality. In a meta-analysis of 4,428 patients, all-cause mortality rose with each fibrosis stage, reaching a relative risk of 3.42 at stage 4 compared with stage 0, and liver-related mortality reached 11.13 (Taylor et al., Gastroenterology, 2020; Ekstedt et al., Hepatology, 2015). That is why guidelines now point everything at fibrosis assessment.

In primary care, FIB-4 is the practical first step. Age, AST, ALT, and platelet count. Under 1.3 suggests low risk and those patients can generally stay in primary care. Above 2.67 means high risk and warrants hepatology referral. Intermediate scores land in a gray zone that usually needs imaging such as FibroScan or a blood-based marker like the ELF test. FibroScan is fast and non-invasive but loses accuracy in patients with obesity, which is a real limitation given who has this disease. MR elastography is the most accurate option and the least available.

Treatment still starts with lifestyle. Weight loss of 5 to 10% improves steatosis and inflammation. The Mediterranean pattern is consistently associated with lower liver fat and better insulin sensitivity. Exercise at 150 minutes a week of moderate activity reduces liver fat even without weight loss, which is worth telling patients who are discouraged by the scale. Cutting sugar-sweetened beverages and limiting fructose is standard advice. Coffee earns its reputation here: a meta-analysis of observational studies found coffee consumption associated with 35% lower odds of significant fibrosis, with three or more cups a day the threshold most often cited, caffeinated or not (Hayat et al., Nutrients, 2021).

Medication options are expanding. Vitamin E has histologic benefit in non-diabetic patients with biopsy-proven MASH, though long-term safety concerns persist. Statins remain badly underused and are safe in MASLD, and they should be prescribed for cardiovascular risk reduction (Kargiotis et al., World J Gastroenterol, 2015). GLP-1 receptor agonists reduce liver fat and support weight loss.

In March 2024, resmetirom became the first FDA-approved drug for MASH with fibrosis. It is a liver-directed thyroid hormone receptor-beta agonist. In the phase 3 MAESTRO-NASH trial, MASH resolution without worsening fibrosis occurred in 25.9% of patients on 80 mg and 29.9% on 100 mg, against 9.7% on placebo, and both doses beat placebo on fibrosis improvement (Harrison et al., NEJM, 2024). It is approved for adults with non-cirrhotic MASH and stage F2 to F3 fibrosis. Those response rates are meaningful and they are also modest, and patients should hear both halves.

Endoscopic and surgical options matter too. Endoscopic sleeve gastroplasty and intragastric balloons reduce liver fat and improve fibrosis. Bariatric surgery remains among the most effective interventions available, with a systematic review and meta-analysis finding NASH resolution in roughly half of patients and fibrosis improvement in about a third (Lee et al., Clin Gastroenterol Hepatol, 2019).

MASLD management has moved well outside hepatology. It needs primary care, cardiology, endocrinology, nutrition, and gastroenterology working the same problem. Screen at-risk patients with FIB-4, particularly those with diabetes or obesity. Counsel on weight and diet. Prescribe statins when indicated. Refer for advanced assessment when fibrosis is suspected.

MASLD reframes liver disease as part of the broader cardiometabolic picture. Treating it means protecting the liver while cutting cardiovascular risk, improving glycemic control, and addressing systemic inflammation. That is where the impact lives.

Scott Rennie, D.O.

References:

1. Rinella ME, Lazarus JV, Ratziu V, et al. A multisociety Delphi consensus statement on new fatty liver disease nomenclature. J Hepatol. 2023;79(6):1542-1556. https://pubmed.ncbi.nlm.nih.gov/37364790/

2. Le MH, et al. Global incidence of non-alcoholic fatty liver disease. Clin Mol Hepatol. 2022;28(4):841-850. https://pubmed.ncbi.nlm.nih.gov/36117442/

3. Taylor RS, et al. Association Between Fibrosis Stage and Outcomes of Patients With Nonalcoholic Fatty Liver Disease: A Systematic Review and Meta-Analysis. Gastroenterology. 2020;158(6):1611-1625.e12. https://pubmed.ncbi.nlm.nih.gov/32027911/

4. Ekstedt M, et al. Fibrosis stage is the strongest predictor for disease-specific mortality in NAFLD after up to 33 years of follow-up. Hepatology. 2015;61(5):1547-1554. https://pubmed.ncbi.nlm.nih.gov/25125077/

5. Hayat U, et al. Effect of Coffee Consumption on Non-Alcoholic Fatty Liver Disease Incidence, Prevalence and Risk of Significant Liver Fibrosis: Systematic Review with Meta-Analysis of Observational Studies. Nutrients. 2021;13(9):3042. https://pubmed.ncbi.nlm.nih.gov/34578919/

6. Kargiotis K, et al. World J Gastroenterol. 2015;21(25):7860-7868.

7. Harrison SA, et al. A Phase 3, Randomized, Controlled Trial of Resmetirom in NASH with Liver Fibrosis. N Engl J Med. 2024;390(6):497-509. https://pubmed.ncbi.nlm.nih.gov/38324483/

8. Lee Y, et al. Complete Resolution of Nonalcoholic Fatty Liver Disease After Bariatric Surgery: A Systematic Review and Meta-analysis. Clin Gastroenterol Hepatol. 2019;17(6):1040-1060.e11. https://pubmed.ncbi.nlm.nih.gov/30326299/

Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

Nutrition and Vitamins After Weight Loss Surgery

On By Dr. Scott RennieIn Weight Loss & Metabolic HealthLeave a comment

Obesity is a chronic metabolic disease, and it disrupts nutrient handling long before surgery enters the conversation. Insulin resistance, chronic low-grade inflammation, altered gut hormones, and environmental exposures all change how nutrients are absorbed and used. Which is why so many patients arrive at a bariatric evaluation already deficient. Iron, vitamin D, B12, and folate are the gaps that show up most often on pre-op screening.

That baseline matters, because surgery does more than shrink the stomach or limit intake. It rewires physiology in ways that improve metabolism and open the door to new deficiencies at the same time.

Take Roux-en-Y gastric bypass. Skipping the proximal small intestine reduces absorption of iron, calcium, and several vitamins. Sleeve gastrectomy cuts ghrelin, the hunger hormone, and also changes how bile acids and gut microbiota handle nutrients. Across procedures, GLP-1 and PYY rise, boosting satiety and improving glucose metabolism, while also setting up the risk of postprandial hypoglycemia down the line. The same shifts that explain the weight loss explain why monitoring isn’t optional.

The nutritional risks are substantial. The 2019 multisociety perioperative guideline, cosponsored by AACE, The Obesity Society, ASMBS, the Obesity Medicine Association, and the American Society of Anesthesiologists, lays out 85 recommendations covering exactly this territory (Mechanick et al., 2019). Vitamin D and calcium deficiency approach universality without supplementation. Thiamine deficiency is easy to miss and clinically urgent when it appears. Iron, folate, zinc, and copper run low frequently, particularly after bypass and biliopancreatic diversion.

Protein deserves its own attention. Guidelines recommend 60 to 100 g/day, and real-world intake falls short of that repeatedly. A systematic review found protein intake below 60 g/day in the majority of studies examined, alongside significant lean mass loss (Ito et al., Obes Surg, 2017). That is the road to sarcopenia after weight loss, which undercuts the metabolic gains the surgery was supposed to deliver. Supplementation trials have tested doses in the 15 to 30 g/day range with mixed results, and a systematic review of the whole literature concluded the evidence for lean body mass preservation remains inconclusive (Nuijten et al., Nutr J, 2021). Worth saying plainly rather than overselling the shake.

For clinicians the plan is simple and demands discipline. Protein first. Multivitamins, calcium citrate with vitamin D, B12, and iron are required rather than suggested. Folate belongs in the plan, particularly for menstruating women and anyone with pre-op anemia. Transdermal patches are emerging for patients who can’t tolerate or adhere to oral supplements, though long-term data are thin.

Follow-up is more than labs. Education, repeated counseling, and multidisciplinary care are what make the difference. Dietitians, endocrinologists, and surgeons all have a role. Telehealth has opened real doors here, and models mixing remote contact with targeted in-person visits appear to improve long-term adherence. Prescriptions alone don’t carry patients through this. Structured support does.

One complication turning up more often is post-bariatric hypoglycemia, especially after Roux-en-Y. These patients present with symptomatic drops in blood sugar after meals, sometimes years out from surgery, driven by exaggerated GLP-1 and insulin secretion. Management usually comes down to lowering dietary glycemic load, cutting concentrated sugars, and spreading carbohydrate evenly through the day. Recognizing it early matters, because it gets misattributed constantly when nobody is thinking about it.

The larger point: bariatric surgery is a powerful intervention and it isn’t a cure. The operation is one part of it. Lifelong nutritional surveillance and metabolic management are the other. Prioritize protein, close the micronutrient gaps, keep follow-up consistent, and outcomes are both safer and more durable.

Scott Rennie, D.O.

References:

1. Mechanick JI, et al. Clinical Practice Guidelines for the Perioperative Nutrition, Metabolic, and Nonsurgical Support of Patients Undergoing Bariatric Procedures: 2019 Update. Endocr Pract. 2019;25(12):1346-1359. Cosponsored by AACE/ACE, TOS, ASMBS, OMA, and ASA. https://pubmed.ncbi.nlm.nih.gov/31682518/

2. Parrott J, et al. American Society for Metabolic and Bariatric Surgery Integrated Health Nutritional Guidelines for the Surgical Weight Loss Patient 2016 Update: Micronutrients. Surg Obes Relat Dis. 2017;13(5):727-741. https://pubmed.ncbi.nlm.nih.gov/28392254/

3. Ito MK, et al. Effect of Protein Intake on the Protein Status and Lean Mass of Post-Bariatric Surgery Patients: a Systematic Review. Obes Surg. 2017;27(2):502-512. https://pubmed.ncbi.nlm.nih.gov/27844254/

4. Nuijten MAH, et al. The effect of additional protein on lean body mass preservation in post-bariatric surgery patients: a systematic review. Nutr J. 2021;20(1):27. https://pubmed.ncbi.nlm.nih.gov/33750392/

Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

Weight Loss Surgery Without Incisions: Bariatric Endoscopy

On By Dr. Scott RennieIn Weight Loss & Metabolic HealthLeave a comment

Obesity is one of the most common health problems we face, and treatment has never kept pace with the need. More than 100 million U.S. adults meet criteria for obesity. Roughly 1% of patients who qualify for metabolic and bariatric surgery actually undergo it in a given year. Lifestyle change and medication help, and plenty of patients either get insufficient benefit or can’t sustain them. That leaves a wide gap, particularly for people with moderate obesity and for those who don’t qualify for surgery.

Bariatric endoscopy is starting to fill it. These are minimally invasive outpatient procedures sitting between lifestyle and pharmacotherapy on one side and surgery on the other. No incisions, lower risk, same-day discharge for most patients. They are also repeatable or reversible, which gives patients and clinicians room to change course.

Intragastric balloons are the simplest example. The device occupies space in the stomach, and patients feel full on less food. Studies consistently show 10 to 15% total body weight loss over six months alongside improvements in insulin resistance and liver health. In a prospective study of patients with NASH and early fibrosis who underwent balloon placement with paired liver biopsies, every patient who lost 10% or more of their weight showed a reduction in NAFLD activity score, 90% had resolution of NASH, and 45% showed fibrosis regression (Bazerbachi et al., Clin Gastroenterol Hepatol, 2021). Small study, striking numbers.

Endoscopic sleeve gastroplasty is the more durable option. An endoscopic suturing device reduces stomach volume, mimicking a surgical sleeve without incisions. MERIT, the first randomized trial of the procedure, compared ESG plus lifestyle modification against lifestyle alone in class 1 and 2 obesity and found the procedure safely induced and maintained weight loss with improvement in metabolic comorbidities (Abu Dayyeh et al., Lancet, 2022). Five-year data from a single-center cohort show mean total body weight loss around 16%, with roughly three-fifths of patients holding 10% or more (Sharaiha et al., Clin Gastroenterol Hepatol, 2021). Compared with surgery it means fewer complications, faster recovery, and preserved native anatomy.

Endoscopic revision is gaining traction too. Transoral outlet reduction addresses weight regain after gastric bypass by tightening the gastrojejunal anastomosis and the pouch, restoring restriction (Jirapinyo & Thompson, Endoscopy, 2018). For patients demoralized by regain, it is a far less invasive option than surgical revision.

Duodenal interventions work differently. Duodenal mucosal resurfacing and duodenal-jejunal bypass sleeves act less on restriction and more on metabolic signaling, with early data showing HbA1c reductions and weight loss in the 9 to 15% range. This is the least mature part of the field and should be described that way to patients.

Safety looks good. Serious adverse events run in the 0.2 to 4% range depending on the procedure. Most problems, nausea and abdominal discomfort, are mild and short-lived. FDA clearance of endoscopic suturing platforms reflects the accumulating evidence on both safety and efficacy.

So who are the candidates? Typically patients with BMI 30 to 50 who haven’t gotten results from diet and exercise alone. It is also an option for people who aren’t ready for surgery or not eligible. Patients who have regained weight after bariatric surgery may benefit, especially from TORe. Comorbidities like diabetes and MASLD factor in, since weight reduction directly improves their course.

The thing to stress is that bariatric endoscopy is a tool rather than a cure, and it doesn’t replace surgery or medication. Outcomes are best when procedures are combined with pharmacotherapy and lifestyle change, which is the same lesson obesity keeps teaching. It is a chronic, relapsing disease and it needs long-term management.

Scott Rennie, D.O.

References:

1. Bazerbachi F, et al. Intragastric Balloon Placement Induces Significant Metabolic and Histologic Improvement in Patients With Nonalcoholic Steatohepatitis. Clin Gastroenterol Hepatol. 2021;19(1):146-154.e4. https://pubmed.ncbi.nlm.nih.gov/32360804/

2. Abu Dayyeh BK, et al. Endoscopic sleeve gastroplasty for treatment of class 1 and 2 obesity (MERIT): a prospective, multicentre, randomised trial. Lancet. 2022;400(10350):441-451. https://pubmed.ncbi.nlm.nih.gov/35908555/

3. Sharaiha RZ, et al. Five-Year Outcomes of Endoscopic Sleeve Gastroplasty for the Treatment of Obesity. Clin Gastroenterol Hepatol. 2021;19(5):1051-1057.e2. https://pubmed.ncbi.nlm.nih.gov/32683103/

4. Jirapinyo P, Thompson CC. Endoscopic bariatric and metabolic therapies: surgical analogues and mechanisms of action. Endoscopy. 2018;50(4):371-377.

5. Ponce J, et al. Surg Obes Relat Dis. 2015;11(4):874-881.

Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

Weight Loss Surgery Risks and How to Lower Them

On By Dr. Scott RennieIn Weight Loss & Metabolic HealthLeave a comment

Bariatric surgery has become one of the most effective treatments for obesity and its complications. Roux-en-Y gastric bypass and sleeve gastrectomy are performed more often now as safety has improved and demand has grown. Surgery is still surgery, and the risks are worth knowing in detail.

The numbers are encouraging. In the LABS Consortium multicenter prospective study, 30-day mortality was 0.3% across 4,776 patients, and major adverse events including venous thromboembolism, reoperation, or extended hospitalization occurred in 4.3% (LABS Consortium, NEJM, 2009). For context, that mortality rate sits below several common major operations. Vigilance still matters, particularly in patients with prior VTE, untreated sleep apnea, poor functional status, or very high BMI.

Among early complications, leaks are what surgeons and patients fear most. Anastomotic leaks occur in about 1% of gastric bypass patients and 2 to 5% after sleeve gastrectomy (Sakran et al., Surg Endosc, 2013; Rosenthal et al., Surg Obes Relat Dis, 2012). Median time to diagnosis is around a week, which usually means the patient is already home. Treatment ranges from drainage and stents to reoperation. Endoscopic vacuum therapy is a newer approach with reported success rates up to 90% (Markus et al., Langenbecks Arch Surg, 2022).

Thrombosis is the other serious early risk. Deep vein thrombosis and pulmonary embolism account for a large share of postoperative deaths, and 70 to 80% of cases occur after discharge (O’Connor et al., Surg Obes Relat Dis, 2021). That timing is the whole problem. There is no universal agreement on extended prophylaxis, and weight-based dosing with enoxaparin is often considered for high-risk patients. Portal vein thrombosis is less common and has been reported almost exclusively after sleeve gastrectomy. These patients present with abdominal pain and are treated with anticoagulation (Parikh et al., Surg Obes Relat Dis, 2017).

Obstruction is a particular concern in bypass patients. Small bowel obstruction can follow adhesions, hernias, or clots, and internal hernias are the tricky ones. Symptoms may be vague, intermittent pain or nausea, or they may present as a full obstruction. Missing it leads to bowel ischemia. A high index of suspicion is the only real defense.

Nutritional problems arrive later and cause real harm when overlooked. Thiamine deficiency can produce Wernicke’s encephalopathy with confusion, ataxia, and nystagmus, and it develops in patients with vomiting or poor intake. Deficiencies in iron, calcium, vitamin D, and B12 are common. Routine supplementation and lab monitoring at three months, six months, and annually thereafter are the standard for good reason (Makarewicz et al., Obes Surg, 2007).

Weight regain is a reality rather than a failure. Roughly one in five patients regains some weight after gastric bypass. Sometimes the cause is behavioral, sometimes anatomical. Either way it is a signal to look more closely, and revisional surgery can be appropriate depending on anatomy and history.

For clinicians, the practical question is when to send a patient back to their bariatric team. Persistent abdominal pain, food intolerance, unexplained weight regain, or concerning deficiencies should all prompt referral. Imaging, endoscopy, or revision may follow.

Bariatric surgery can transform a patient’s life and substantially improve comorbidities. The benefits come attached to responsibilities: careful preoperative evaluation, surgical expertise, and long-term follow-up. Patients do best when both they and their providers understand what can go wrong and stay alert for the early signs.

Scott Rennie, D.O.

References:

1. Longitudinal Assessment of Bariatric Surgery (LABS) Consortium. Perioperative safety in the longitudinal assessment of bariatric surgery. N Engl J Med. 2009;361(5):445-454. https://pubmed.ncbi.nlm.nih.gov/19641201/

2. Sakran N, et al. Surg Endosc. 2013;27(1):240-245.

3. Rosenthal RJ, et al. International Sleeve Gastrectomy Expert Panel Consensus Statement. Surg Obes Relat Dis. 2012;8(1):8-19. https://pubmed.ncbi.nlm.nih.gov/22248433/

4. O’Connor EA, et al. Surg Obes Relat Dis. 2021;17(7):1218-1225.

5. Parikh M, et al. Surg Obes Relat Dis. 2017;13(11):1835-1839.

6. Markus PM, et al. Langenbecks Arch Surg. 2022;407(3):1039-1047.

7. Makarewicz W, et al. Wernicke’s syndrome after sleeve gastrectomy. Obes Surg. 2007;17(5):704-706. https://pubmed.ncbi.nlm.nih.gov/17658034/

Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

Weight Loss Surgery Options for Obesity Explained

On By Dr. Scott RennieIn Weight Loss & Metabolic HealthLeave a comment

Weight loss surgery, also called bariatric or metabolic surgery, is one of the most effective treatments available for severe obesity. Gastric bypass and sleeve gastrectomy are safer now than they have ever been, and demand keeps climbing. Surgery carries risk and requires a long-term commitment, and both belong in the conversation from the first visit.

Obesity affects more than 100 million U.S. adults, roughly 40.3% of the adult population, with 9.7% in the severe range (NCHS, NHANES August 2021 to August 2023). Type 2 diabetes, cardiovascular disease, cancer, and early death all track with excess weight. Lifestyle programs and medications help, and for many patients the results don’t hold. That is the gap surgery fills. The Swedish Obese Subjects study followed patients for over a decade and found surgery produced durable weight loss and lower mortality (Sjöström et al., NEJM, 2007), and a retrospective cohort found a 40% reduction in all-cause mortality after gastric bypass (Adams et al., NEJM, 2007).

So who qualifies? Under the 2022 ASMBS and IFSO guidelines, surgery is recommended for people with BMI over 35 regardless of comorbidity, and for BMI 30 to 34.9 in patients with metabolic disease that has not responded to medical therapy (Eisenberg et al., Surg Obes Relat Dis, 2022). That is a meaningful loosening from the 1991 NIH thresholds most clinicians still carry in their heads. There is no strict age cutoff, though surgeons approach adolescents and older adults with extra care.

Before surgery, patients go through a thorough workup: nutrition and psychology evaluations, cardiac and pulmonary assessment, sometimes a sleep study and endoscopy. Smoking cessation is required. Most insurers still ask for documentation of six months of supervised weight management, a requirement with no good evidence behind it that delays care for people who need it. That time does get used for preparation and education, which is the one argument in its favor.

Several procedures are available. Sleeve gastrectomy is the most common worldwide. About 80% of the stomach is removed, limiting intake and changing hunger hormones. Patients typically lose 55 to 60% of excess weight. The operation is shorter than bypass and hospital stays run one to two days. Worsening reflux is the main downside (Peterli et al., JAMA, 2018).

Roux-en-Y gastric bypass has decades of long-term data behind it. A small pouch connects to the small intestine, bypassing part of the digestive tract. Average weight loss runs 60 to 70% of excess weight, diabetes remission rates are high, and reflux often improves. Risks include vitamin deficiencies, marginal ulcers, and internal hernias (Higa et al., Surg Obes Relat Dis, 2011).

One anastomosis gastric bypass simplifies the technique and shows promising results for weight and comorbidities, with higher risk of bile reflux and deficiencies. Duodenal switch and SADI combine a sleeve with intestinal rerouting. These are the most powerful options for diabetes remission and weight loss and they demand the most careful long-term monitoring. Gastric banding is now rare. It once looked appealing because it was reversible and low-risk, and the weight loss proved modest while long-term reoperation rates ran high (Genco et al., Surg Obes Relat Dis, 2016).

The randomized evidence is strong. Trials by Mingrone, Schauer, and Ikramuddin all demonstrated higher diabetes remission with surgery than with medical therapy alone, and the Schauer and Mingrone cohorts held those differences out to five and ten years (Schauer et al., NEJM, 2012 and 2017; Mingrone et al., Lancet, 2015 and 2021; Ikramuddin et al., JAMA, 2018).

Weight regain happens. About one in five patients regains some weight after bypass, from changes in anatomy or lapses in eating and activity. Surgeons can offer revision: re-sleeving, converting sleeve to bypass, or tightening pouches. These get tailored to the individual.

Long-term success depends on follow-up. Regular labs, nutrition counseling, ongoing team support. Lifelong vitamin and mineral supplementation is required rather than optional. Behavioral support matters, because habits carry as much weight as anatomy over years.

Weight loss surgery is one of the most powerful tools we have for a disease that is otherwise progressive and difficult to manage. With careful preparation, modern technique, and sustained follow-up, patients see improvements in weight, health, and quality of life that few other interventions produce.

Scott Rennie, D.O.

References:

1. National Center for Health Statistics. Prevalence of Overweight, Obesity, and Severe Obesity Among Adults Age 20 and Older: United States, August 2021–August 2023. https://www.cdc.gov/nchs/data/hestat/obesity-adult-17-18/obesity-adult.htm

2. Sjöström L, et al. Effects of bariatric surgery on mortality in Swedish obese subjects. N Engl J Med. 2007;357(8):741-752. https://pubmed.ncbi.nlm.nih.gov/17715408/

3. Adams TD, et al. Long-term mortality after gastric bypass surgery. N Engl J Med. 2007;357(8):753-761. https://pubmed.ncbi.nlm.nih.gov/17715409/

4. Eisenberg D, et al. 2022 American Society for Metabolic and Bariatric Surgery (ASMBS) and International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO) Indications for Metabolic and Bariatric Surgery. Surg Obes Relat Dis. 2022;18(12):1345-1356. https://pubmed.ncbi.nlm.nih.gov/36280539/

5. Schauer PR, et al. N Engl J Med. 2012;366(17):1567-1576; and N Engl J Med. 2017;376(7):641-651.

6. Mingrone G, et al. Lancet. 2015;386(9997):964-973; and Lancet. 2021;397(10271):293-304.

7. Ikramuddin S, et al. JAMA. 2018;319(3):266-278.

8. Peterli R, et al. Effect of Laparoscopic Sleeve Gastrectomy vs Laparoscopic Roux-en-Y Gastric Bypass on Weight Loss in Patients With Morbid Obesity: The SM-BOSS Randomized Clinical Trial. JAMA. 2018;319(3):255-265. https://pubmed.ncbi.nlm.nih.gov/29340679/

9. Higa K, et al. Surg Obes Relat Dis. 2011;7(4):516-525.

10. Genco A, et al. Surg Obes Relat Dis. 2016;12(10):1783-1788.

Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

How the Gut Affects Diabetes and Metabolic Disease

On By Dr. Scott RennieIn Weight Loss & Metabolic HealthLeave a comment

When we think about metabolic disease, attention goes to blood sugar, insulin, and fat. Another organ drives much of the process quietly, and it is the gut.

Calling the gut a digestive tube undersells it badly. It is a complex, dynamic system that shapes how we handle nutrients, regulate hormones, and respond to infection. Researchers now treat it as central to metabolic health, and that shift has opened new thinking about both prevention and treatment.

Consider what it actually contains. Its own nervous system, sometimes called the second brain. An endocrine system producing GLP-1, PYY, and ghrelin. A major site of immune defense. And constant interaction with the trillions of microbes living inside it. Together these systems determine how food gets processed, when fullness registers, and how glucose is regulated (Seeley et al., Cell Metab, 2015).

The gut-brain conversation is the powerful part. Signals move both directions. Hormones, nerve messages, and bacterial metabolites all feed into how the brain regulates appetite and metabolism. This is a large part of why simple calorie counting fails so often. The gut can override willpower, and the brain listens closely to what it says.

Bariatric surgery demonstrates the whole system in action. Vertical sleeve gastrectomy and Roux-en-Y gastric bypass do far more than reduce stomach size. They produce wide-reaching changes in gut physiology that explain why they work so well for weight loss and diabetes control. After surgery, GLP-1 rises, insulin sensitivity improves, food preferences shift, and bile acid metabolism changes. The gut barrier tightens, which reduces inflammation. Most striking of all, patients often defend a new, lower body weight afterward, which suggests the whole regulatory system has reset (Stefater et al., Gastroenterology, 2010). Bile acid signaling appears central to that reset, and it holds across procedures (Myronovych et al., Obesity, 2014).

Nutrient signaling changes too. Iron metabolism is altered after surgery, and the change has been linked to HIF-2α signaling pathways that also improve glucose handling and GLP-1 release (Evers et al., Cell Rep, 2022). Adaptations like that are hard to explain with mechanical restriction alone.

The microbiome is another piece. Surgery shifts bacterial composition toward communities associated with healthier metabolism, and barrier function improves alongside it. Molecules like Reg3g strengthen the gut lining, increasing mucus and reducing leakiness, which lowers systemic inflammation and metabolic stress (Shin et al., Cell Metab, 2022).

These insights point toward treatments that skip the operating room. GLP-1 receptor agonists reproduce some of the hormonal effects seen after bypass or sleeve. Bile acid modulators, microbiome therapies, and strategies targeting iron signaling are all under study as ways into the same pathways.

Seen this way, the gut is where the body decides how to use energy, how to balance hormones, and how to regulate immunity. For patients, that science explains why surgery and gut-focused medications can make such a difference. For clinicians, it suggests the most effective treatment plans will be the ones that respect what the gut is actually doing.

Scott Rennie, D.O.

References:

1. Seeley RJ, Chambers AP, Sandoval DA. The role of gut adaptation in the potent effects of multiple bariatric surgeries on obesity and diabetes. Cell Metab. 2015;21(3):369-378. https://pubmed.ncbi.nlm.nih.gov/25662404/

2. Stefater MA, et al. Sleeve gastrectomy induces loss of weight and fat mass in obese rats, but does not affect leptin sensitivity. Gastroenterology. 2010;138(7):2426-2436. https://pubmed.ncbi.nlm.nih.gov/20226189/

3. Myronovych A, et al. Vertical sleeve gastrectomy reduces hepatic steatosis while increasing serum bile acids in a weight-loss-independent manner. Obesity (Silver Spring). 2014;22(2):390-400. https://pubmed.ncbi.nlm.nih.gov/23847068/

4. Evers SS, et al. Cell Rep. 2022;38(11):110487.

5. Shin JH, et al. Cell Metab. 2022;34(5):747-761.e6.

Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.