TL;DR:

Most diets fail because your body thinks you’re starving—not because you lack willpower. Cutting calories slows your metabolism, increases hunger hormones, and triggers cravings for high-calorie foods. Real, lasting weight loss happens when you fix insulin resistance, support metabolism, and eat in a way that keeps your hormones balanced.

Leptin resistance, ghrelin, and stress hormones—not willpower—explain why calorie restriction usually ends in rebound weight gain.

Every January, millions start new diets—and most end up heavier a year later. The reason isn’t lack of willpower, but biology. Ever since Dr. Lulu Hunt Peters came up with the concept of calories in 1914, all weight loss programs involve eating less. Unfortunately, diets make you fat.

Fat cells are not inert; they produce a hormone called leptin. The hypothalamus in the brain monitors leptin levels. When you diet, you lose fat. This reduces the amount of leptin perceived by the hypothalamus. Your body interprets this as starvation. People who carry around a lot of extra fat make a lot of extra leptin. The hypothalamus gets used to the high levels of leptin. This is known as leptin resistance, and it gets in the way of losing weight. So even if you are fat, losing too much weight is still perceived as starvation3.

A second hormone, ghrelin, is known as the hunger hormone. When we lose weight, the stomach releases greater amounts of a hormone called ghrelin. This hormone makes us feel hungry. Everyone has this hormone, but if you’ve been overweight and then lose weight, the hormone level increases. These hormonal shifts make “eat less, move more” ineffective as a long-term strategy and are now recognized in obesity research as key drivers of weight regain.

Your body will do several things when it perceives that it is starving:

  • Your metabolism slows down: Weight loss affects the thyroid, which is the thermostat of the body. You produce less “T3”, which is the active thyroid hormone. This means that for any given activity, you will burn fewer calories1,2.
  • You become hungry: Your brain thinks you are starving because of the drop in leptin levels. Ghrelin levels increase after a diet4. People who are overweight commonly have leptin resistance. Loss of fat causes a drop in leptin.
  • You crave high-calorie and (possibly) processed food: Processed food, which is high in sodium and high fructose corn syrup, may increase ghrelin levels5,7,8, thus increasing hunger. In other words, processed foods interfere with feeling satisfied after a meal. So, it plays out like this, your leptin levels drop, you get really hungry and eat a McMeal. The McMeal is high in calories but does not fully satisfy your hunger, and you eat some more. Lather, rinse, repeat.

This Has Nothing to Do with Willpower

If you have dieted in the past, you may have noticed a pattern. The first week usually goes well, with significant weight loss. The second week is harder, and there is less weight loss because your metabolism is slowing down. After some time, even basic discipline becomes difficult. Sometimes you are able to complete the diet, but the maintenance portion is too difficult. Sometimes the weight is lost but is regained over time. Most people fail at dieting because of the hormonal mechanisms mentioned above, not because they lack will power. For the most part, limiting food intake to lose weight is not successful. You can have rapid weight loss, or you can have permanent weight loss, but not both.

Do Something Different

Weight & Insulin Insensitivity

Since dieting triggers survival mechanisms, the goal isn’t restriction—it’s metabolic retraining. What you eat and when you eat is more important than how much you eat. This is a marathon, not a sprint. They should learn how to eat and to work toward glycemic control (most people who are overweight are insulin insensitive).

Junk Food Addiction

Fight addiction: Michael Moss is an author from the New York Times who writes about the fast-food industry. Junk food companies use neurologists and pet scans to see what “foods” light up our pleasure centers. They work on making junk food addictive. Processed foods not only alter leptin and ghrelin but hijack the brain’s dopamine reward system, reinforcing food addiction behaviors.

During a diet a person gives up their addictive foods while drastically lowering calories. Leptin levels drop—signaling the body is starving. They crave their addictive foods even more. It is a recipe for rebound weight gain. Identify and avoid trigger foods without limiting the amount. Do not let yourself get hungry—just avoid bad food.

Address insulin insensitivity at the same time—and you will lose weight. When you plateau and you are used to the new way of eating, you can try some modest calorie restriction or increase exercise.  You can find online tools where you can plug in your weight and activity level to find caloric need. Use that as a guideline to slightly reduce caloric intake (5% or less—if you start craving, you’ve lowered it too much).

Start with This

  • Eat only at meal times—no snacking.
  • Absolutely no food between dinner and bedtime
  • Eat slowly, chew food until it is liquid
  • No foods with a glycemic load greater than 10. I actually prefer the Roadmap to Health (click here to find it). It has low glycemic foods, helps the microbiome, and avoids foods that people are commonly sensitive to.
  • Nutrients that improve insulin sensitivity—such as berberine, magnesium, and certain B vitamins—can make the transition easier. Give berberine, magnesium, and a multiple (some companies make multiples formulated for blood sugar control, like CGF from Zorex. Other companies make similar products. The supplements will help with glycemic control

Find and Eliminate Problem Foods

Reducing inflammatory foods can improve insulin sensitivity and appetite regulation, likely explaining much of the weight loss benefit observed. I will give Oxford Labs a plug here. They have a test that looks for foods that cause inflammation. This is NOT a hidden “allergy” test.  After the test, the patient only eats foods that do not cause inflammation for 30 days. No caloric restriction. People lose weight on this program (plus a lot of other things get better). Also, the Coca pulse test may help to identify problem foods—and it is free.

Bottom line—you need to relearn how to eat before weight loss is considered. Also, finding and identifying other health needs will help you with weight loss. You may find that supporting thyroid, adrenal, or the microbiome helps a great deal. They need to focus on getting healthy, Keith Richards is thin—you want to do better than that.

Frequently Asked Questions

Why do most diets fail?
Most diets trigger a “starvation response.” When you eat too little, your body produces less leptin (the fullness hormone) and more ghrelin (the hunger hormone). This slows metabolism and makes you crave high-calorie foods.

Is it true that processed foods make you hungrier?
Yes. Processed foods—especially those high in sugar or refined carbs—disrupt hormones that control appetite and reward. They satisfy cravings temporarily but make you hungrier later.

What’s the best way to lose weight long term?
Focus on balancing your metabolism, not restricting calories. Eat real food at regular meal times, avoid snacking, manage stress, and support insulin sensitivity. When your hormones are balanced, fat loss becomes easier and more sustainable.

Do supplements help with metabolism?
Some nutrients—like magnesium and berberine—support normal blood sugar balance and energy metabolism. They can help the body respond better to food, but they’re most effective when combined with a healthy, balanced diet.

Can inflammation affect weight loss?
Yes. Inflammation interferes with insulin sensitivity and hormone balance. Identifying and reducing inflammatory foods (for example, using the LEAP test or Coca pulse test) can make it easier to lose weight naturally.

References:

  1. 2014 Jan;24(1):19-26 Moderate weight loss is sufficient to affect thyroid hormone homeostasis and inhibit its peripheral conversion
  2. Int J Obes. 1990 Mar;14(3):249-58. Effects of a very low calorie diet on weight, thyroid hormones and mood
  3. Arch Pharm Res. 2013 Feb;36(2):201-7. Molecular mechanisms of central leptin resistance in obesity
  4. N Engl J Med 2002 May 23;346(21):1623-30 Plasma ghrelin levels after diet-induced weight loss or gastric bypass surgery
  5. 2016 May 26;8(6):323. Elevation of Fasting Ghrelin in Healthy Human Subjects Consuming a High-Salt Diet: A Novel Mechanism of Obesity?
  6. Obesity (Silver Spring). 2015 Feb;23(2):313-21 Effects of α-lipoic acid and eicosapentaenoic acid in overweight and obese women during weight loss
  7. Nutr Diabetes. 2013 Dec 23;3(12):e99 Ghrelin receptor regulates HFCS-induced adipose inflammation and insulin resistance
  8. J Clin Endocrinol Metab. 2004 Jun;89(6):2963-72 Dietary fructose reduces circulating insulin and leptin, attenuates postprandial suppression of ghrelin, and increases triglycerides in women