Experts talked about the reasons for weight loss after a diet

Reducing the calorie content of the diet helps to reduce weight, but it can be more difficult to maintain the result than to achieve initial weight loss. After losing body weight, the body may consume less energy, and changes in appetite regulation may increase hunger. Therefore, the return of kilograms is associated not only with eating habits, but also with physiological adaptation. Why weight loss slows down over time and what helps to maintain the result is in the Izvestia material.

How Calorie Restriction Works

Calorie-restricted diets are based on creating an energy deficit: a person gets less from food than the body consumes. Internal reserves, including fat reserves, are used to cover the difference, and body weight decreases over time.

At the same time, the need for energy is individual. It depends on age, gender, body composition, physical activity, and health status. Therefore, the same caloric intake for one person may mean a deficit, while for another it may correspond to his needs.

Approaches to food restriction also vary. Some suggest a moderate daily calorie reduction, while others suggest alternating days with regular and limited meals. When eating in a certain time window, a person shortens the period during which they eat. However, changing the time of meals by itself does not guarantee that the total energy consumption will decrease.

It is important to distinguish between the stage of weight loss and its subsequent maintenance. After achieving the result, the task changes: you need to build a diet that meets the new needs of the body and that can be maintained for a long time.

Why the first results do not guarantee a long-term effect

Research confirms that energy restriction can reduce body weight and waist circumference. But the result in a few weeks does not automatically allow you to judge whether it will be preserved in a year.

In a systematic review and online meta-analysis published in 2024 in the International Journal of Behavioral Nutrition and Physical Activity, researchers combined data from 47 randomized trials involving 3,363 adults. They compared constant energy restriction, nutrition in a limited time window, and different options for intermittent fasting.

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All the approaches studied generally contributed to weight loss compared to a regular diet. However, the duration of follow–up varied significantly: 40 studies presented results for one to three months, while data for seven to 12 months were available in only six papers.

This limits the ability to assess the sustainability of the effect. In addition, the results of studies of different duration cannot be perceived as a mandatory scenario for each person: weight loss does not occur for everyone at the same time.

Why do you want to eat more after losing weight

Weight loss is accompanied by changes in the systems that regulate hunger and satiety. A person may feel the urge to eat more often and be less satisfied with the usual portion.

Therefore, maintaining the result requires effort even after completing active weight loss. The achieved figure on the scales does not in itself mean that appetite will immediately return to its previous level.

In a review published in the journal Medical Clinics of North America, researchers Kevin Hall and Scott Kahan examine the biological, behavioral, and environmental factors that make it difficult to maintain weight. They note that changes in appetite may play a more significant role in the formation of plateaus than a slowdown in metabolism. The authors emphasize the need for long-term support in the treatment of obesity and separate work to maintain the achieved result.

Why does the body start using less energy?

As you lose weight, energy consumption changes. Part of the decrease is due to a decrease in body weight: the body becomes smaller, and maintaining its work requires a different amount of energy. But this is not always the end of the changes. A review published in the journal Experimental Gerontology describes metabolic adaptation — a reduction in energy expenditure that may exceed what is expected, taking into account the loss of fat and fat-free mass.

Researchers attribute this process to several factors, including changes in hormonal regulation and energy efficiency. The severity of this adaptation may vary. In practice, this means that a diet on which weight was reduced at the beginning may eventually create a smaller deficit. The loss of kilograms slows down, and sometimes the weight stops changing for a while — a plateau occurs.

As Probst and Wills point out, this reaction should not be explained by the popular notion of "starvation mode." The body continues to expend energy, but its needs and response to dietary restrictions change. A plateau in itself does not prove that the metabolism has "broken down."

Why is it not limited to willpower

Physiological changes occur in an environment where high-calorie food is available and convenient. The authors of the publication draw attention to the prevalence of inexpensive products with a high degree of processing, which can make it difficult to adhere to a restrictive diet for a long time.

At the same time, constant hunger can affect mood, sleep, and relationships with food. If the chosen regime requires continuous suffering of severe discomfort, it becomes more difficult to comply with it for months. Therefore, regaining some of the lost weight cannot be automatically considered a sign of insufficient discipline. The result is simultaneously influenced by appetite, energy consumption, food availability, and the ability to maintain selected habits.

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This also explains why completing a diet requires a thoughtful transition. Returning to the previous diet may mean consuming more energy than the body needs now.

What helps to keep the result

Probst and Wills recommend focusing on the quality of the diet and habits that can be maintained for a long time. In particular, they pay attention to the adequate intake of protein and the inclusion of fiber—rich foods such as vegetables, legumes and whole grains, which help to form a more satisfying diet.

The Australian government resource Eat for Health advises planning basic meals and snacks in advance, considering portion sizes and finding suitable ways to increase daily activity.

Another approach is to eat more carefully: take your time, reduce distractions, and notice signals of hunger and satiety. Meal planning helps to reduce the number of random decisions when food choices have to be made in a hurry.

At the same time, the diet should take into account the state of health. The authors of the source material separately warn against self-restrictive diets during pregnancy and breastfeeding, in childhood and adolescence, as well as with a history of eating disorders. If the change in appetite has no clear cause and is accompanied by dizziness, severe fatigue, or difficulty concentrating, experts recommend contacting a doctor.

Weight loss is a separate stage that should be planned along with weight loss. It requires taking into account the changed needs of the body, proper nutrition and support, which allows you to maintain the result without constantly increasing restrictions.