Intermittent fasting is better for losing weight, but not fat, says study

A clinical study revealed that time-restricted eating, known as intermittent fasting, is better for weight loss, but not necessarily fat loss.

The practice, characterized by eating in windows of 10 hours or less followed by fasting, also had better results for blood pressure and mood, when compared to a feeding program of 12 hours or more.

Experts, however, are divided on the real benefits of this type of diet.

Conducted with 90 obese people between 25 and 75 years old, the work developed at the University of Alabama at Birmingham, in the United States, showed that patients who fasted had a weight loss of 2.3 kg more than the group control.

However, no significant total fat loss was identified, although, in a secondary analysis, the data indicated a segmental decrease in fat in the abdominal region.

The clinical study does not make it clear how the weight loss occurred, as there was no change in body fat. According to experts, weight loss may be a reflection of variables such as hydration or hormonal changes. According to the research, there was also no significant loss of lean mass, although previous studies suggest that this may be a limitation of the diet.

Endocrinologist at the Mater Dei Hospital in Belo Horizonte, Patrícia Corradi, says there is no scientific consensus on the role of time-restricted food in weight loss. According to her, the variety of studies available, carried out with different parameters, generates different results.

“There is no indication of fasting as a weight loss strategy in the main recommendations. What we have are some metabolic benefits, such as insulin resistance”, he says.

Even so, for the endocrinologist, it is worth betting on this type of food program if the patient adapts well to the practice. “It is a way of inducing a caloric deficit by restricting the number of meals, and these meals must necessarily have the number of calories controlled.”

All participants in the research, published in early August in the journal JAMA Internal Medicine, were instructed to do physical activity and eat a low-calorie diet, with 500 calories less than their resting metabolic rate.

The study was done at 14 weeks and 80% of the patients were women. The consumption window of the group that did intermittent fasting was between 7 am and 3 pm. This means that, before or after this time, the participants could not eat.

“There is another study that was published in The New England Journal of Medicine that had more or less the same proposal, but with a duration of one year. It did not show this benefit in relation to weight loss”, says Corradi. “This is a sign that this strategy can be used within a periodization”, says the endocrinologist, explaining that fasting can be adopted for seasons, interrupting the practice before the body gets used to it and the strategy becomes less effective.

The University of Alabama study also showed improvement in diastolic blood pressure in the group that practiced fasting. The mood, measured by a questionnaire given to the patients, also had alterations, which were manifested in a decrease in fatigue and an increase in vitality.

Nutritionist Gisele Magalhães, a participant in Janela da Escuta, an extension and research program at the UFMG School of Medicine (Federal University of Minas Gerais), defends that healthy eating with few industrialized products and without pesticides, physical exercise, water and a good night of sleep, are the best habits for a healthier day to day.

“When we go into fasting, many times we can’t go without food for longer, but when it’s time to eat, we can lose control, which is not healthy. The conclusion is that that good old way of stones healthy habits is the best. There is still no magic formula.”

The nutritionist warns that intermittent fasting can trigger eating disorders, in addition to causing hypoglycemia, drop in blood pressure and loss of muscle and water, among other problems. Magalhães also reinforces that this type of diet should not be done by children and adolescents, who need regular consumption of food to ensure cognitive development.

“The risk is greater than the benefit. It’s one thing for us to have a survey with the monitored people. Another is for you to be in your daily life, fasting and, suddenly, in 40 degrees, fainting because you’re alone drinking water. I think the risks are greater than the benefits”, he says.

According to her, respecting one’s hunger when choosing meal times and following the guidelines of the Food Guide for the Brazilian Population, a document from the Ministry of Health that gathers guidelines for adequate nutrition, are practical and effective measures for a healthy life and for the slimming. “In general, when we respect our hunger, we also have an improvement in the response of losing or not gaining weight.”