Fasting is gaining recognition for its positive effects, with a growing body of research backing its benefits. However, a recent study urges caution as it highlights potential health risks associated with it. Here’s what that controversial new study really shows.
Water fasts, which involve individuals consuming solely water for multiple days, may contribute to weight loss, but the permanence of this loss remains uncertain, as per a study conducted at the University of Illinois Chicago. Additionally, other metabolic advantages such as reduced blood pressure and improved cholesterol levels seem to be fleeting once the fasting period concludes, as discovered by the researchers.
Krista Varady, a professor of kinesiology and nutrition who spearheaded the research, published in Nutrition Reviews, states that while there are no severe side effects identified with water fasts or similar low-calorie fasting methods, the metabolic benefits tend to evaporate rapidly.
“My overall conclusion is that I guess you could try it, but it just seems like a lot of work, and all those metabolic benefits disappear.”
Varady emphasized the importance of medical supervision if someone is considering engaging in such fasts beyond five days.
Varady, a specialist in intermittent fasting, said that she became interested in water fasting last autumn when she suddenly began receiving calls from reporters asking her opinion on it. She reasoned that before making a remark, she should look into the relevant studies.
This new research comprises an analysis of eight studies centered on water fasting and Buchinger fasting, a type of medically supervised fasting common in Europe, in which participants consume minimal quantities of juice and soup daily. The team evaluated these studies to comprehend the cumulative effects on weight loss and various metabolic elements.
They observed that fasting resulted in significant short-term weight loss: around 4% to 6% for a five-day fast, 2% to 10% for seven to ten days, and 7% to 10% for 15 to 20 days.
Only a handful of these studies monitored weight regain post-fasting. In one instance, participants regained all the weight lost through a five-day water fast within three months. In two other cases, only a small percentage of the lost weight was regained; however, these studies encouraged participants to limit caloric intake post-fasting.
Conversely, the metabolic benefits of fasting seemed transient, as blood pressure, cholesterol, and blood sugar improvements vanished shortly after normal eating resumed.
Some studies included individuals with Type 1 and Type 2 diabetes, who displayed no adverse reactions to fasting, albeit with close monitoring and insulin adjustments.
According to Varady, the most typical negative symptoms of these extended fasts were hunger, headaches, and sleeplessness. In the investigations, there were no fatal or very detrimental outcomes, such as metabolic acidosis.
Varady highlighted that participants lost approximately two-thirds of their weight in lean mass and one-third in fat mass during these prolonged fasts, contrary to conventional weight loss where fat loss exceeds muscle loss. She attributed this to the body’s need for consistent protein intake and its reliance on muscles when this is absent.
Varady’s previous investigations into intermittent fasting examined its efficacy for weight loss and specific issues such as impacts on fertility, which she found to be non-existent.
Varady would recommend intermittent fasting over water fasting to those seeking weight loss, citing more extensive data supporting its efficacy in weight management.
The study also involved UIC researchers Sofia Cienfuegos, Shuhao Lin, Vasiliki Pavlou, Kelsey Gabel, and former UIC student Mark Ezpeleta.
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