The 2 Key Reasons Calorie-Restrictive Diets Fail

Kaspars Grinvalds/Shutterstock

Calorie counting fails for weight loss and usually leads to long-term weight gain. This pattern of yo-yo dieting is a well-recognized danger of calorie-restricted diets.

Long-term calorie-restriction diets result in two key adaptations that stymie further weight loss:

1. Decreased metabolic rate.
2. Increased hunger.

Successful long-term weight loss and weight maintenance requires focusing on fixing the underlying hormonal cause of obesity, rather than just calories.

A key to the scientific understanding of calorie restriction for weight loss is that a number of the key assumptions underlying this theory are false. When we lose weight through calorie restriction, the basal metabolic rate usually falls, too. It’s partially this resulting lowered basal metabolic rate (BMR) that ultimately dooms weight loss efforts. We hope that over time, the BMR will go back up toward “normal,” but unfortunately, studies show that it does not. BMR falls with calorie-restricted diets and hunger increases, but worse, over time, these changes do not revert back to baseline but continue to worsen. This is proven by many of the scientific studies done over the years. Let’s take a look.

Basal Metabolic Rate (BMR)

Long-term persistence of adaptive thermogenesis in subjects who have maintained a reduced body weight by Dr. Rosenbaum et al.

In this study, subjects who experienced a 10 percent weight loss were noted to have a reduced total energy expenditure (TEE) of about 300 to 400 calories a day. We hope maintaining that weight loss over time allows TEE to go back up to baseline. But it does not. Even by the end of the study—one year—the TEE did not go up but actually continued to go down further, an average of almost 500 calories a day.

In other words, this slowed metabolic rate (which reduces weight loss efforts) starts almost immediately after caloric reduction and persists for a long time—at least one year and going strong.

Hunger

New England Journal of Medicine

This study, published in the prestigious New England Journal of Medicine in 2011, clearly demonstrates the effect of weight loss through calorie restriction on hunger. This study is almost a decade old, so none of this information is exactly new. Using a liquid shake diet (51 percent carbohydrates), researchers reduced caloric intake to cause a 13.5-kilogram average weight loss and then tried to maintain it over a year with a low-fat diet.

Despite participants’ best intentions, almost half of the weight was regained over the year. But what were the hormonal effects of this diet/weight loss?

Hormonal Change

Researchers measured the hormone ghrelin, sometimes called the hunger hormone. The higher the ghrelin, the hungrier we are. Ghrelin levels moved higher during the weight loss phase, but the higher levels persisted even after a year. The hormone peptide YY, a satiety hormone released in response to protein and fat, was also measured. Essentially, peptide YY makes us feel full. During the initial weight loss phase, peptide YY dropped and stayed low even after 62 weeks. The results for the other satiety hormones, amylin and cholecystokinin, are similar.

What does this all mean? It means when you lose weight by restricting calories, you feel more hungry and less full (satiated). Even after a year, the feeling of hunger never leaves. This isn’t some psychological voodoo from weight loss or loss of willpower effect. Subjects were hungrier because their hunger hormones were higher and their satiety hormones were lower. There was a good physiologic reason for their hunger: the hormonal changes caused by calorie restriction.

New England Journal of Medicine

Guaranteed to Fail

Let’s put all this together. Suppose you weigh 200 pounds and eat 2,000 calories per day. Because your weight is stable, you must also burn 2,000 calories per day (TEE). One day, you decide to lose weight and start a calorie-reduced diet but don’t change the types of foods much, nor meal timing. You now eat 1,600 calories per day, and to start, the weight comes down, say to 180 pounds. So far, so good.

In response to the weight loss and calorie restriction, we know from the many scientific studies done over the years that the body will respond in a predictable manner. First, your body will reduce its TEE by 300 to 400 calories per day. So instead of burning 2,000 calories per day, you will only burn 1,600. This means that you will feel colder, more tired, and fatigued. But weight loss will also slow down because if you eat 1,600 calories and burn 1,600, there is no caloric deficit and, therefore, no weight loss.

Thought Catalog/Unsplash

The second predictable response is that your body increases hunger signaling by increasing ghrelin (the hunger hormone) and decreases satiety hormones (peptide YY, cholecystokinin). This makes you hungrier than before and increases your desire to eat. While you are consciously trying to eat less, your body is trying to make you eat more. This persists day after day, week after week, year after year.

The end result: weight regain. This, of course, is obvious to anybody who has ever been on a diet. This has NOTHING to do with a lack of willpower of any kind or moral failure. It is simply a hormonal fact of life. These are all real, measurable, and well-known physical effects of calorie restriction.

So here’s the bottom line. Focusing on caloric restriction alone for weight loss is virtually guaranteed to fail because of the two hormonal responses (decreased energy expenditure and increased hunger). This is why these diets have consistently failed despite thousands of doctors and dieticians giving this terrible advice over the last 50 years.

TheFastingMethod.com

This is the vicious cycle of undereating.

• Eat less.
• Lose some weight.
• Metabolism slows, and hunger increases.
• Weight starts to rise again.
• Redouble our efforts by eating even less.
• A bit more weight comes off.
• Metabolism slows more, and hunger increases.
• Weight starts to be regained.
• Repeat the cycle until intolerable.

At some point, we simply cannot follow this diet anymore. We increase our calories back up a little because we are feeling so tired and hungry. As we do, the weight returns to where it started. Friends, family, and medical professionals now blame the victim by secretly thinking it is “their fault” they could not lose the weight. They feel the person trying to lose weight is a failure with insufficient willpower. But willpower had nothing to do with the failure of calorie-restricted diets. It is all just physiology, aka, our hormones.

Republished from TheFastingMethod.com