Is intermittent fasting good for weight loss? Experts weigh in

Intermittent fasting is the superstar amongst those who aim to lose weight. From 6/8, 5:2, alternate-day fasting, and 24-hour fasts, there are different kinds of fasts, depending on their potential weight loss effects. But whether this time-restricted eating really helps with weight loss is still the calorie-burning question! A new study has looked into the potential benefits of intermittent fasting and suggests that it could offer even more.

A study by the researchers from the University of Mississippi suggests that intermittent fasting paired with exercise increases fat loss over the activity alone. The study published in the International Journal of Obesity found that when healthy adults pair an eight-hour eating window with regular exercise, they lose more fat, without sacrificing lean muscle, compared to exercise alone.

“We saw that this did lead to more fat loss and reduced body fat percentage over time when healthy adults were following both exercise with time-restricting eating, compared to those who were only exercising for at least 4 weeks. It is important to note lean mass preservation,” Nadeeja Wijayatunga, assistant professor of nutrition and hospitality management, said in a statement.

Wijayatunga and co-author Michael Hays, a tactical dietitian and recent graduate of the university, conducted a systematic review and meta-analysis of 15 previous studies on the subject, spanning the past decade. Time-restricted eating is one of many diets included in the umbrella term intermittent fasting.

“People like time-restricted eating because they feel it’s easier to adhere to because they don’t have to think too much. It’s all about time, not calorie-counting or watching out for certain foods,” she said.

The popularity of intermittent fasting has quickly risen, especially in the United States, with 12% of Americans having tried it, according to the 2023 International Food and Health Survey.

However, the science surrounding time-restricted eating is still developing, Hays said.

How to prevent muscle loss?

“For some people, this may be a good technique to help with body composition goals. It's just another tool, but more studies need to come out to really understand how this works in humans,” Hays added.

Hays also noted that there was a slight difference between people who exercised while following a time-restricted diet and those who used exercise alone, but the two groups were already very healthy individuals.

“In most cases, these were healthy adults. They were already physically fit and already had exercise routines. When you already have athletic, lean people and you decrease their body fat percentage, that’s significant,” Hays said.

Though time-restricted diet is hailed for its weight loss effects, it has been criticized for possibly leading to a loss of lean mass, including all the muscles, organs, and other tissues that make up the human body.

“We need healthy muscles. Muscles are really important for the body and for your metabolism. If we lose muscle, it may impact our metabolic systems, and it just decreases mobility overall,” Wijayatunga said.

This study found that when time-restricted eating is paired with exercise, it does not lead to a reduction in lean mass, even for those who lost body fat.

“That’s why you want to couple diet with exercise. When you’re losing weight, you never want to lose lean tissue. You want to lose fat,” Hays said.

“What I’d recommend is implementing healthy habits in a way that you, as an individual, can maintain, with guidance from a health care professional,” she added.