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.