Studying the effect of different diets on weight is well-known to be difficult. Above all, since it is almost impossible to control exactly what people eat and drink. At the same time, the demand for answers about which method is the best for losing weight is enormous.
In a new study from the USA, researchers have made an attempt to compare two different methods for losing weight.
A total of 165 people with overweight or obesity were randomly assigned to one of two diets. In the first group, participants fasted three days a week and ate freely during the rest of the week. On fasting days, they were allowed to eat a little - approximately 20 percent of what they ate on a "normal day". In the second group, participants were instead given restrictions on how many calories they were allowed to eat each day.
Fasting resulted in the greatest weight loss
After one year, participants in the 4:3 group had on average reduced their weight by 7.6 percent. In the other group, the weight loss was 5 percent. 58 percent of those in the 4:3 group lost at least 5 percent of their weight during the study period, compared to 47 percent in the other group. Losing 5 percent is usually considered a relevant goal.
Mai-Lis Hellénius, a doctor and professor at the Karolinska Institute, thinks the study is well-conducted and interesting. But according to her, it is not enough to recommend intermittent fasting instead of calorie restriction and advice on what to eat.
The method shows results on weight loss, which is good, but I want to see more long-term results on health.
Exercise is crucial
Participants in both groups in the study received gym memberships and were encouraged to engage in physical activity for at least 300 minutes per week. This is good, Hellénius thinks.
It is becoming increasingly clear that sedentary behavior is a major health hazard. We need to eat more healthily but also exercise much more than most people do today, she says.
One criticism she directs at the study is that it does not show what the participants ate. The instructions were a distribution of calories where 55 percent should come from carbohydrates, 15 percent protein, and 30 percent fat.
There is a big difference in whether the carbohydrates consist of fruit or candy and whether the fat is animal or vegetable, she says.
