Over the years, the increased prevalence of obesity and related metabolic diseases has also reflected an increase in dietary interventions that restrict energy intake in order to promote weight loss. Among them is the restriction of caloric energy (CER), which involves a daily energy deficit of 500 to 750 kcal, as well as intermittent fasting (JI) that alternates feeding periods with periods of complete fasting or with very limited caloric intake.
Intermittent Fasting Variations
Intermittent fasting is a comprehensive term that encompasses different variations of fasting regimens, with fasting on alternate days (JDA) and 5:2 diet and time-restricted feeding (ART) being the most frequent applications. The JDA regimen consists of a day of fasting alternated with a day of feeding at will, and may be of the kind in which no food or caloric drink is consumed on fasting days and modified JDA in which caloric intake during fasting days represents 20% to 30% of normal food intake. At ART, in turn, individuals fast for 14 to 16 hours a day and consume food at will in the food windows for 4 to 12 hours.
It is worth mentioning that the literature suggests that these three main forms of intermittent fasting are effective interventions for weight loss, producing reductions in body weight that vary approximately from 1% to 13% over 2 to 52 weeks.
Intermittent Fasting vs. Traditional Caloric Restriction
Studies show that there is no statistically significant difference when both are comparator, although when compared to each other and classified as to the efficacy of weight loss, the JDA diets were more likely to occupy the first place because they were the most effective for weight loss, i.e., a weight loss range of 0.77% to 12.97% over 3 to 26 weeks compared to the other regimens.
In addition, the 5:2 diet produced weight loss ranging from 1.7% to 7.97%, while art ranged from 0.95% to 8.60% of body weight loss. It is important to note that a meta-analysis concluded that intermittent fasting, regardless of type, led to similar weight loss compared to traditional caloric restriction.
The maximum duration of studies involving intermittent fasting is 12 months, which limits applicability to long-term health outcomes. On the other hand, the literature shows that intermittent fasting is promising as a weight control strategy for people with normal weight and a weight loss strategy for overweight and obese people.
Finally, results of studies suggest that intermittent fasting should be implemented as an alternative strategy to traditional caloric restriction for weight loss and weight control, adapting to the specific needs and acceptance of the individual.
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: Elortegui Pascual P, Rolands MR, Eldridge AL, et al. A meta-analysis comparing the effectiveness of alternate day fasting, the 5:2 diet, and time-restricted eating for weight loss. Obesity (Silver Spring). 2023;31 Suppl 1:9-21. doi:10.1002/oby.23568