Tag: weight loss

Why Your Body Fights to Regain the Weight You Lost

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

As physicians, we often see patients who manage to lose weight but can’t seem to keep it off. One of the biggest physiological reasons is adaptive thermogenesis. Understanding what it is, and how the brain adapts too, helps explain why long-term maintenance is so hard.

Adaptive thermogenesis is the body’s way of conserving energy after weight loss. Drop a significant amount of weight, and the body needs fewer calories to function. That makes it harder to hold on to the new weight. The research goes back decades and shows the effect clearly: people who lose ten percent or more of their body weight need roughly 300 to 400 fewer calories a day to maintain that weight than someone at the same size who never lost it (Leibel et al., NEJM, 1995; Rosenbaum et al., Am J Physiol, 2003).

It’s easiest to picture with two patients. Same height, same weight, same activity. One has always been at that weight. The other lost ten percent to get there. The second patient has to eat several hundred calories less, or burn that much more through activity, just to stay even. That’s the metabolic disadvantage weight-reduced patients live with.

What makes this harder is that adaptive thermogenesis doesn’t fade away. Studies show the effect can last for years, even after weight stays stable (Sumithran et al., NEJM, 2011; Rosenbaum et al., JCI, 2008; Martins et al., AJCN, 2020). This isn’t a short-lived adjustment. Patients have to adjust to the reality that the body keeps pushing back against weight maintenance, sometimes for years after the loss.

The brain changes too. Imaging studies show heightened activity in reward and decision-making regions like the globus pallidus, insula, and ventral striatum after weight loss. Food looks more appealing. Cravings get stronger, and resisting them gets harder. Meanwhile regions tied to satiety and control, the hypothalamus and cingulate gyrus among them, go quiet. Patients feel less full, notice their intake less, and have less control over eating. It’s a setup for regain.

Despite these challenges, there are lessons from people who succeed. The National Weight Control Registry has followed thousands of long-term maintainers. On average they eat about 100 to 150 fewer calories daily than peers at the same weight who never lost it. They move more, roughly 45 extra minutes of activity a day. They watch less television, and they show consistent awareness and restraint around eating. Nothing flashy. It just works against the biology.

Exercise, aerobic and resistance both, raises energy expenditure and helps preserve muscle mass, which supports metabolism. Mindful eating and careful tracking help patients avoid unintentional increases in intake. Structured programs and social support provide accountability, which matters when the body is working against the patient. Regular follow-up visits help sustain those behaviors.

Adaptive thermogenesis and brain adaptations stack the deck against weight maintenance. Understanding the physiology makes it easier to set realistic expectations, though, and to design strategies that work with a patient’s biology instead of against it.

Scott Rennie, D.O.
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.

References:

  • 1. Leibel RL, Rosenbaum M, Hirsch J. Changes in Energy Expenditure Resulting from Altered Body Weight. N Engl J Med. 1995;332:621-628. https://pubmed.ncbi.nlm.nih.gov/7632212/
  • 2. Sumithran P, Prendergast LA, Delbridge E, et al. Long-Term Persistence of Hormonal Adaptations to Weight Loss. N Engl J Med. 2011;365:1597-1604. https://pubmed.ncbi.nlm.nih.gov/22029981/
  • 3. Rosenbaum M, et al. Effects of experimental weight perturbation on skeletal muscle work efficiency in human subjects. Am J Physiol Regul Integr Comp Physiol. 2003;285:R183-R192. https://pubmed.ncbi.nlm.nih.gov/12609816/
  • 4. Rosenbaum M, et al. Leptin reverses weight loss-induced changes in regional neural activity responses to visual food stimuli. J Clin Invest. 2008;118:2583-2591. https://pubmed.ncbi.nlm.nih.gov/18568078/
  • 5. Martins C, Roekenes J, Salamati S, Gower BA, Hunter GR. Metabolic adaptation is an illusion, only present when participants are in negative energy balance. Am J Clin Nutr. 2020;112:1212-1218. https://pubmed.ncbi.nlm.nih.gov/32844188/

Why Exercise Matters for Obesity Beyond Weight Loss

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

When we counsel patients about obesity management, one of the most common misconceptions is that exercise by itself is the best way to lose weight. On video visits, patients often tell me they’ve started walking every day or signed up for the gym, expecting big changes in their weight within weeks. Sometimes even clinicians lean into that belief. But the data consistently show that diet has a much stronger impact on weight loss than exercise alone.

That doesn’t mean physical activity isn’t important. Far from it. The average weight loss from exercise alone is modest, usually around two to three kilograms. Add diet changes, and outcomes improve significantly. Patients who combine both tend to lose more weight and, more importantly, keep it off better.

The role of exercise extends well beyond weight loss itself. It preserves lean body mass, lowers blood pressure, improves cholesterol, and supports long-term physical function. Pharmacotherapy shows the same pattern: medications can drive the weight loss, but adding structured activity makes the results more sustainable.

The type of activity matters. Aerobic exercise, walking, cycling, swimming, drives calorie expenditure, but resistance training helps maintain or build muscle, which matters most when calories are reduced. The combination works best. Most recommendations center around 150 minutes of moderate-intensity activity per week, which can mean brisk walking 30 minutes a day, five days a week. Some patients prefer high-intensity interval training because it takes less time, though not everyone tolerates it well. For beginners, discomfort and injury risk run higher, so starting gradually makes sense.

It’s important to manage expectations. When a patient logs on discouraged because an exercise program hasn’t led to major weight loss, that’s a teaching moment. Diet has to be part of the plan too, and exercise alone was never going to get there. Once patients understand that, they’re more willing to combine strategies instead of giving up.

Adherence and enjoyment are often the deciding factors. People stay consistent when they choose activities they actually like. One patient may thrive on group classes, another prefers solitary walks with a podcast. Both approaches work, if they’re done regularly.

Daily habits outside the gym matter too. Non-exercise activity thermogenesis, or NEAT, is the energy used in everyday movement: standing during phone calls, walking instead of driving short distances, taking the stairs instead of the elevator, plus gardening, housework, walking a dog, small things patients can relate to. Increasing NEAT can meaningfully raise daily calorie burn without feeling like a formal workout.

For us as providers, diet drives most of the weight loss, but physical activity is essential for maintaining it and for overall health. Framing it this way helps patients set realistic expectations while reinforcing that movement stays a regular part of life.

Reference:

Swift DL, McGee JE, Earnest CP, Carlisle E, Nygard M, Johannsen NM. The Effects of Exercise and Physical Activity on Weight Loss and Maintenance. Prog Cardiovasc Dis. 2018;61(2):206-213. https://pubmed.ncbi.nlm.nih.gov/30003901/

Scott Rennie, D.O.

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.

Does Meal Timing Affect Your Metabolism and Health?

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

When you eat can matter as much as what you eat. Not a fad, a measurable physiological pattern, and one most people never think to adjust. Timing affects weight management, metabolic health, and even the risk of chronic disease, and the field studying the connection between circadian rhythms and eating patterns has a name: chrononutrition.

Typical eating habits in the U.S. don’t line up well with what the research suggests is healthiest. Most people eat less than a quarter of their daily calories before noon, and more than a third after 6 p.m. The average eating window stretches nearly fifteen hours a day (Gill and Panda, 2015). That long, backloaded pattern is linked to higher body fat, worse glucose tolerance, and poorer metabolic outcomes.

Evidence favors eating earlier. In one trial, people who made breakfast their largest meal had better glucose and insulin control, felt more satisfied during the day, and lost more weight than those who made dinner the main meal (Jakubowicz et al., 2013). That tracks with circadian biology: the body handles nutrients more efficiently in the morning than late at night.

Breakfast does more than supply calories. Regular breakfast eaters tend to take in more vitamins and minerals overall (St-Onge et al., 2017), and they show lower rates of obesity and more stable weight over time. Skipping breakfast, by contrast, tracks with higher BMI, larger blood sugar swings, and greater cardiovascular risk.

Time-restricted eating fits the same pattern. Narrow the eating window to eight or twelve hours and total calorie intake often falls on its own, insulin sensitivity improves, and fat oxidation increases (Gill and Panda, 2015). Early time-restricted eating, where meals cluster in the morning and early afternoon, improves appetite control and fat metabolism specifically (Ravussin et al., 2019).

Intermittent fasting runs on the same logic. The most common version is 16:8: fast sixteen hours, eat during an eight-hour window. Alternate-day fasting has also been studied, and it produces weight loss similar to plain calorie restriction, though dropout rates run higher (Trepanowski et al., 2017).

What the science of chrononutrition shows is that timing matters. Shifting more calories to the first part of the day improves metabolism and weight control, breakfast and early meals set the body up for better glucose regulation and satiety, and time-restricted eating and intermittent fasting add tools on top of that, especially when they lean toward earlier eating windows rather than later ones. For patients, these strategies are often more about changing the clock than drastically changing the plate.

Scott Rennie, D.O.
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.

References:

  • Gill S, Panda S. A Smartphone App Reveals Erratic Diurnal Eating Patterns in Humans that Can Be Modulated for Health Benefits. Cell Metabolism. 2015;22(5):789-798. PMID 26411343. https://pubmed.ncbi.nlm.nih.gov/26411343/
  • Jakubowicz D, et al. High Caloric Intake at Breakfast vs. Dinner Differentially Influences Weight Loss of Overweight and Obese Women. Obesity (Silver Spring). 2013;21(12):2504-2512. PMID 23512957. https://pubmed.ncbi.nlm.nih.gov/23512957/
  • St-Onge MP, et al. Meal Timing and Frequency: Implications for Cardiovascular Disease Prevention. Circulation. 2017;135:e96-e121. PMID 28137935. https://pubmed.ncbi.nlm.nih.gov/28137935/
  • Ravussin E, et al. Early Time-Restricted Feeding Reduces Appetite and Increases Fat Oxidation But Does Not Affect Energy Expenditure in Humans. Obesity (Silver Spring). 2019;27(8):1244-1254. PMID 31339000. https://pubmed.ncbi.nlm.nih.gov/31339000/
  • Trepanowski JF, et al. Effect of Alternate-Day Fasting on Weight Loss, Weight Maintenance, and Cardioprotection Among Metabolically Healthy Obese Adults. JAMA Intern Med. 2017;177(7):930-938. PMID 28459931. https://pubmed.ncbi.nlm.nih.gov/28459931/

Can You Do Intermittent Fasting on Ozempic or Wegovy?

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

Weight comes up in almost every visit I do. For some patients it is fifteen pounds standing between them and a better blood pressure number. For others it is obesity that has already done damage, and the conversation starts further back. The work can feel overwhelming from the inside. What’s changed is that the tools finally match the size of the problem. Medications like Ozempic, Wegovy, Mounjaro, and Zepbound, the GLP-1 receptor agonists, have shifted how this is approached, and paired with a structure like intermittent fasting they help people lose weight and keep it off.

What GLP-1 Agonists Do

These drugs mimic glucagon-like peptide-1, a hormone that regulates appetite and blood sugar. Given as medication, they slow gastric emptying and push stronger satiety signals to the brain, so fullness arrives earlier and stays longer. They also improve insulin sensitivity, which is why they earned their place in type 2 diabetes first.

The weight effect is substantial. Wegovy and Zepbound carry FDA approval specifically for weight loss. Ozempic and Mounjaro are approved for diabetes and produce strong weight results as well, which is the source of most of the confusion patients arrive with about which drug is which.

How They Work With Intermittent Fasting

Intermittent fasting improves insulin sensitivity, supports fat loss, and helps regulate hunger hormones. Staying with it is the hard part. Many patients tell me they can’t get past the hunger. GLP-1 medications change that equation by blunting appetite and cravings, which makes a fasting schedule something a person can actually hold.

A patient of mine started a 16:8 fasting plan (16 hours fasting, 8 hours eating) while on a GLP-1 medication. Before starting the medication, she felt shaky and irritable during fasting. After starting, she was surprised by how manageable it felt. She ate smaller meals, felt full, and didn’t struggle to maintain the fasting window.

Side Effects and Adjustments

Nausea leads the list, and it’s worst early. Diarrhea and reflux show up too. Most of it settles as the body adapts. Start low, titrate slowly, and resist the urge to chase the next dose because the scale stalled for two weeks. Patients who stay in contact through the titration get their dose adjusted before they quit over side effects, and the ones who go quiet are the ones who stop the drug entirely.

Barriers to Access

Getting these medications is its own project. Cost is the main wall. Insurance coverage for weight loss remains inconsistent in a way that’s hard to explain to a patient who has just been told the drug would help, and out-of-pocket pricing is punishing. Demand has outrun supply, so delays and shortages are part of the picture.

Then there are the compounded versions. Some pharmacies sell them well below brand pricing, and they’re not FDA-approved. Safety and potency can’t be guaranteed. I tell patients to stay away from them, and I don’t soften that advice when someone pushes back on price.

Putting It Into Context

These aren’t quick fixes. They are tools, and they work when they sit on top of durable changes: balanced eating, regular activity, attention to mental health. Intermittent fasting is one workable way to structure eating alongside them. The lifestyle piece doesn’t become optional because a medication is doing part of the lifting.

When patients pair the medication with habits they can sustain, results hold longer and vary less. The goal is a set of strategies that still works three years from now, not the fastest possible drop on the scale.

Scott Rennie, D.O.

Sources

U.S. Food and Drug Administration. FDA Approvals: Wegovy, Zepbound.

Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. N Engl J Med. 2021;384:989-1002.

Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022;387:205-216.

American Diabetes Association. Pharmacologic Approaches to Glycemic Treatment: Standards of Medical Care in Diabetes, 2024. Diabetes Care. 2024;47(Suppl 1):S181-S202.

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.

Wall clock with illustrations of various foods representing mealtime hours

Does Intermittent Fasting Work? A Doctor Explains

On By Dr. Scott RennieIn Weight Loss & Metabolic HealthLeave a comment
snake-diet-fasting

Intermittent fasting, sometimes called therapeutic fasting or intermittent energy restriction, has gained attention both in the media and in clinical practice. Patients ask about it regularly, often because they’ve heard it can help with weight loss or with lowering blood sugar in diabetes.

I have no ties to pharmaceutical companies or research groups, and I don’t profit from sharing this information. My purpose is simply to explain what I’ve seen and what the research shows. For patients with diabetes or heart disease, or those taking medications, I always recommend making changes under the guidance of a physician. Fasting can alter medication needs quickly, sometimes within days.

Why Weight Matters

About 75% of adults in the United States are overweight or obese, and the number continues to rise. Excess weight contributes to metabolic syndrome, diabetes, hypertension, and heart disease, and it increases the risk of stroke and some cancers. Many patients struggle with arthritis or back pain from the mechanical stress of extra weight. Others develop sleep apnea, fatigue, or sexual dysfunction. Beyond the health issues, there are real-world effects: trouble traveling, difficulty exercising, and limits on daily activities.

Why “Eat Less, Move More” Falls Short

The common advice is to cut calories and exercise more. Most patients I’ve seen have tried this approach at some point. The problem is that it rarely works long term; weight usually returns, often within months.

A striking example came from contestants on The Biggest Loser. Many lost large amounts of weight during the show, but most regained it later. As one participant admitted, “we’re all fat again.” Research supports this. A 2012 study in the New England Journal of Medicine followed patients on calorie restriction and found no sustained improvement in BMI after five years. The Women’s Health Initiative produced similar results over nine years.

The reason is physiology. When calorie intake drops, the body adapts by slowing its metabolism. If someone weighs 230 pounds and cuts back to 1500 calories a day, the body may drop its resting burn rate to 1300 calories. That person feels cold, sluggish, and hungry. Hormones like ghrelin keep signaling hunger, even long after dieting begins, and eventually weight creeps back.

The Role of Insulin

Energy comes from two sources: food and stored fat. When we eat, insulin rises and directs the body to store extra energy as glycogen or fat. At the same time, fat breakdown is switched off. This makes weight loss difficult if insulin stays high, especially with frequent meals or a high-carbohydrate diet.

How Intermittent Fasting Works

Intermittent fasting lowers insulin levels by reducing the frequency of eating. With food energy unavailable, the body taps into fat stores. Fasting can be combined with any diet, but it works particularly well with lower carbohydrate intake, since that also keeps insulin levels down.

Patients use different fasting schedules. A common one is the 16:8 approach, where meals are limited to an 8-hour window. Some prefer one meal a day. Others follow alternate-day fasting or the 5:2 pattern, eating normally for five days and restricting calories for two.

Water intake is essential. During fasting, the body needs extra water to help mobilize fat for energy. Electrolytes, especially sodium, potassium, magnesium, and calcium, also need attention, since ketosis increases their loss through the kidneys. Many patients avoid “keto flu” symptoms like dizziness, fatigue, or cramps by adding broth or electrolyte-rich foods.

What the Evidence Shows

Fasting does not slow metabolism. In fact, studies have shown a slight increase in metabolic rate during fasting, partly due to rises in norepinephrine (Zauner C, Am J Clin Nutr 2000;71:1511-1515). Hunger doesn’t keep building either. Ghrelin levels rise and fall around usual mealtimes, then settle back if food is skipped.

Research also shows fasting preferentially burns fat rather than muscle (Drenick EJ, Am J Public Health Nations Health. 1968;58(3):477-484). Men and women both respond with fat loss, averaging about half a pound per fasting day in controlled studies.

Beyond weight, there are possible additional benefits. Animal studies suggest longer lifespan, reduced cancer risk, and protection against neurodegenerative conditions. Human research is still developing, but some studies show improved insulin sensitivity, better blood sugar control, and even improved mood and cognition.

Safety and Practical Considerations

Fasting is not new. Hippocrates wrote about it, Plato praised it, and major religions have incorporated fasting traditions for centuries, from Ramadan to Lent to the Jewish high holy days. In most overweight patients it is safe when supervised. It is not appropriate for those who are pregnant, underweight, or struggling with eating disorders.

Patients with diabetes, especially those on insulin, need careful monitoring. Many see rapid improvements in blood sugar and may require lower doses. Some patients with type 1 diabetes using low-carb diets report more stable glucose and lower A1c.

For patients who like numbers, tools exist to track progress. Ketone meters can show if the body is burning fat. Blood sugar meters can help patients see how specific foods affect them. Insulin testing is available in labs, but not over the counter.

The Bottom Line

Intermittent fasting is not a fad. It is a structured way to reduce insulin, tap into fat stores, and improve metabolic health. Like any medical intervention, it should be individualized. With guidance, many patients find fasting more sustainable than calorie restriction and more effective for long-term weight control.

Scott Rennie, D.O.

Sources

  • Zauner C, et al. Resting energy expenditure in short-term starvation is increased as a result of an increase in serum norepinephrine. Am J Clin Nutr. 2000;71:1511-1515.
  • Drenick EJ, et al. Prolonged starvation as treatment for obesity. Am J Public Health Nations Health. 1968;58(3):477-484.
  • Sumithran P, et al. Long-term persistence of hormonal adaptations to weight loss. N Engl J Med. 2011;365:1597-1604.
  • Look AHEAD Research Group. Long-term effects of a lifestyle intervention on weight and cardiovascular risk factors. N Engl J Med. 2013;369:145-154.

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.

Vintage balance scale holding fresh tomatoes, carrots, broccoli, and greens

How Do You Actually Lose Weight? A Doctor Explains

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

Disclosures: I have no conflicts of interest with pharmaceutical companies or research groups, and I don’t make money from sharing this information. My purpose is to provide educational value for patients and colleagues. If you’re on medications for diabetes, hypertension, or heart disease, work with a physician who understands nutrition and diet so adjustments can be made safely.

Weight management is one of the biggest health challenges we face in the U.S. About 75% of Americans are overweight or obese, and that number keeps climbing. Obesity contributes to metabolic syndrome, diabetes, heart disease, stroke, arthritis, sleep apnea, and several cancers. It also lowers energy, reduces confidence, and limits mobility. Patients often tell me they can’t do the things they imagined doing in retirement, like traveling, because of joint pain, back problems, or poor stamina.

Measuring Weight and Risk

In medicine, we usually start with Body Mass Index (BMI), which compares weight to height. A BMI of 18.5-24.9 is considered normal, 25-29.9 overweight, 30-39.9 obese, and 40 or higher morbidly obese. BMI isn’t perfect, especially in athletes with high muscle mass; for them, body fat percentage is more accurate. Obesity is defined as 25% body fat or more for men and 32% or more for women.

Why Weight Loss Is So Hard

Patients often tell me they’ve tried diets, lost a few pounds, then stalled or regained. Many describe feeling cold, hungry, and irritable when cutting calories. Even when weight loss succeeds, it often rebounds, the familiar yo-yo effect.

Part of this is due to how the body regulates weight. Think of it as a “set point.” If you’ve been 230 pounds for years, your body may accept that as its new baseline. If you then cut calories, your metabolism adapts by slowing down. Instead of burning 1800 calories a day, your body may drop to 1300. You feel sluggish, chilled, and hungry. Weight loss slows, and sometimes you even gain despite eating less.

The Role of Insulin

Insulin is usually discussed in the context of diabetes, but it’s central to weight regulation. Our blood can only hold about one teaspoon of sugar, roughly 4 grams, at any time. When we eat carbohydrates, they break down into sugar, and insulin moves that sugar into cells. Excess gets stored as fat.

This mechanism is protective. In times of famine or illness, stored fat can be used for energy. But in modern life, where high-carb foods are constantly available, insulin is triggered frequently. That keeps the body in fat-storage mode and blocks fat breakdown (lipolysis).

Carbohydrates, Fat, and Protein

Carbohydrates include sugars, starches, and grains, but also fruits and vegetables. Foods like rice, pasta, potatoes, and bread raise blood sugar the most, leading to higher insulin release. Federal nutrition advice pushed hard in this direction: the 1977 Senate report Dietary Goals for the United States recommended that most calories come from carbohydrate, and the USDA Food Guide Pyramid that followed in 1992 carried the same message. Since then, obesity and diabetes rates have surged (Micha R, et al. JAMA. 2017;317(9):912-924).

Fat was once vilified, but the story is more nuanced. Eating fat doesn’t necessarily make you fat. Fat provides satiety and doesn’t cause the same insulin spikes that carbohydrates do. Traditional populations consuming higher-fat diets often have lower rates of obesity and diabetes. Fats that are liquid at room temperature, such as olive, avocado, or nut oils, are generally healthier than industrial seed oils like soybean or corn.

Protein is essential, but too much can be converted into sugar through gluconeogenesis. I usually recommend moderate protein intake, since overeating protein can work against weight loss by raising glucose levels.

A Practical Approach: Low Carbohydrate, High Fat (LCHF)

For many patients, shifting to a low-carb, higher-fat diet is effective. It reduces insulin spikes, promotes fat burning, and increases satiety. Foods that fit well include avocados, eggs, nuts, fatty fish, cheese, olive oil, and non-starchy vegetables. Processed foods, sugary drinks, cereals, pastries, and high-carb snacks usually derail progress.

One example I often share with patients: compare a 300-calorie soda to 300 calories of eggs and avocado. The soda doesn’t trigger satiety hormones like leptin and ghrelin, so you don’t feel full. The eggs and avocado, higher in fat and protein, send stronger signals of fullness and reduce the urge to keep eating.

The Role of Exercise

Exercise is valuable for mood, cardiovascular health, and strength. But weight loss depends more on diet. A single cookie may contain 200 calories. You can eat it in seconds, but it takes a 20-minute run to burn it off. Most people can’t out-exercise a high-calorie, high-carb diet.

Alcohol and Weight

Alcohol can complicate weight loss. Beer and sugary cocktails are carb-heavy. Wine and spirits without mixers are lower, but alcohol lowers inhibitions, making it easy to overeat. Patients trying to lose weight need to be mindful about drinking.

Safety in Diabetes

Low-carb, high-fat diets can be safe and beneficial in both type 1 and type 2 diabetes, but medication adjustments are often required. Many patients with type 2 diabetes reduce or even stop insulin once carbs are lowered. Patients with type 1 often report more stable blood sugars and improved A1c. Close monitoring with a physician is critical.

Side Effects and Adjustments

Some patients experience “keto flu” when transitioning from carbs to fat metabolism. Symptoms include fatigue, nausea, irritability, and cramps. They usually resolve in a few days with hydration and adequate electrolytes. Because ketosis increases sodium loss, patients may need to add salt, about 5 grams a day total, from foods or broth, unless restricted for heart failure or severe hypertension. Magnesium, potassium, and calcium should also be maintained.

A rare but important issue is cholesterol. About 10% of patients on a low-carb, high-fat diet may see an increase in LDL cholesterol. Most improve, but it’s worth monitoring.

Tools for Tracking

Some patients like evidence that they’re in ketosis. Urine test strips are unreliable. Blood ketone meters, similar to glucose meters, are more accurate. Even patients without diabetes can use glucose meters to see how food choices affect their blood sugar. Unfortunately, there’s no simple home test for insulin levels, but labs can measure it when needed.

Intermittent Fasting

Intermittent fasting fits naturally with low-carb eating. Eating once or twice a day allows insulin levels to fall further, encouraging fat breakdown. Patients may consume the same total calories, but spacing meals differently can improve insulin sensitivity and fat loss. Early research also suggests fasting may reduce cancer risk and extend lifespan, though more studies are needed (Longo VD, et al. Cell Metab. 2014;19:181-192).

The Bottom Line

Weight gain is complex, but insulin, carbohydrate intake, and the body’s set point all play key roles. Shifting to a low-carb, higher-fat diet can help reset metabolism, improve diabetes, and reduce reliance on medications. Adding intermittent fasting may enhance those effects.

Patients should approach these strategies carefully, ideally with medical guidance, especially if they take insulin or blood pressure medications. Done properly, this approach helps with far more than weight. It improves energy, mood, and long-term health.

Scott Rennie, D.O.

Sources

  • Sumithran P, et al. Long-term persistence of hormonal adaptations to weight loss. N Engl J Med. 2011;365:1597-1604.
  • Micha R, et al. Association Between Dietary Factors and Mortality From Heart Disease, Stroke, and Type 2 Diabetes in the United States. JAMA. 2017;317(9):912-924.
  • Longo VD, Mattson MP. Fasting: Molecular Mechanisms and Clinical Applications. Cell Metab. 2014;19:181-192.

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.