Why fasting from time to time is healthier than constantly restricting calories

Based on 2015 Probability of an Obese Person Attaining Normal Body Weight: Cohort Study Using Electronic Health Records. Calorie restriction helps 1 in 210 men and 1 in 124 women lose weight. Why doesn't this method work? According to nutritionists, it’s not a lack of willpower, but a slowdown in metabolism.

Calorie restriction slows down metabolism, but fasting does not

Calorie restriction diets are only effective for a short period of time, until the metabolism starts to slow down in response to nutrient deficiencies. By limiting calorie intake, we literally force the body to "shut down." In this state, the weight actually decreases, but as soon as the calorie consumption becomes less than their consumption, the excess weight returns.

Short-term fasting does not have this effect. It triggers hormonal adaptations that don't occur with simple calorie restriction. Our insulin levels are decreasing Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism., increases the level of norepinephrine (which speeds up metabolism) and growth hormone growth hormone, which helps maintain muscle mass. A randomized pilot study comparing zero-calorie alternate-day fasting to daily caloric restriction in adults with obesity. …

During fasting, glycogen stored in the liver is first burned. When it ends, fatty deposits begin to be burned. And since the body has enough fuel, the metabolism does not slow down.

The body gets used to a limited number of calories and does not burn internal fat

In 2016, scientists compared the effect of fasting every other day and daily calorie restriction on obese people A randomized pilot study comparing zero-calorie alternate-day fasting to daily caloric restriction in adults with obesity. … The experiment lasted 24 weeks, during which the participants in the first group consumed 400 kcal less than their usual norm, and the participants in the second ate as usual, but fasted every other day.

The researchers concluded that short-term fasting is a safe and effective technique.

Although fasting is only marginally superior to diet in terms of overall weight loss, nearly double the body fat is lost during it.

In addition, diets usually do not take into account such a biological phenomenon as homeostasis - the body's ability to adapt to a changing environment.

Our eyes adjust wherever we are, in the bright sun or in the dark. The same thing happens with calorie restriction weight loss. The body adjusts to new conditions, slowing down the metabolism. And when we go back to the old calorie intake, we put on weight again. Therefore, intermittent fasting is more effective than diet.