Fasting plan matched calorie cutting for weight loss in obesity trial
An Adelaide University study found intermittent fasting produced similar weight loss with less perceived effort than daily calorie restriction.
By Tom Brennan · Health & Medicine Correspondent
3 min read
Intermittent fasting helped adults with obesity lose about as much weight as daily calorie restriction in an 18-month clinical trial, Adelaide University researchers reported. The difference, according to the university, was that people assigned to fasting did not describe the same constant need to monitor and limit what they ate.
The findings, published in Clinical Nutrition, point to a possible alternative for people who struggle to stay with conventional diets. Researchers examined weight loss alongside eating behavior, mood, sleep and quality of life.
More than 200 adults with obesity joined the trial and were randomly placed in one of three groups, according to Adelaide University. One group followed an intermittent fasting plan, another cut calories every day, and a third received standard care with healthy eating guidance while continuing their usual diets.
How the diets worked
The intermittent fasting group ate 30% of their daily energy needs between 8 a.m. and noon on three nonconsecutive days each week, Adelaide University said. Participants then fasted for 20 hours after that eating window and ate their usual diet on the remaining days.
The daily calorie-restriction group consumed about 70% of their normal calorie intake each day. The standard-care group did not follow either dieting schedule, according to the university.
After six months, people in both dieting groups had lost an average of about seven kilograms, the researchers reported. Participants in the standard-care group lost about two kilograms over the same period.
Adelaide University said both diet groups also reported improvements in depression and overall well-being, including among people on fasting days. The study did not present fasting as superior for total weight loss, but it found differences in how participants experienced the two approaches.
Less reliance on constant control
People in the daily calorie-restriction group reported that weight loss required ongoing effort to consciously limit food intake and avoid overeating, according to the researchers. Adelaide University said that perceived control accounted for an estimated 15% of their weight loss.
Participants using intermittent fasting did not report the same pressure to count calories, continuously watch intake or resist overeating to get similar results, the university said. Professor Leonie Heilbronn, from Adelaide University’s School of Medicine and the South Australian Health and Medical Research Institute, said many diets can reduce weight but can be hard to maintain, making long-term weight control more difficult.
Heilbronn said the results suggest intermittent fasting could provide another route for people who find standard dieting difficult. She also said psychological and behavioral effects play a large role in whether people can adhere to diets, and fasting may help some people lose weight in ways less dependent on conscious restriction.
The research team said more work is needed to understand the long-term psychological and behavioral effects of intermittent fasting compared with traditional calorie restriction. Heilbronn said future trials should identify people who have difficulty improving eating behaviors, because they may be better suited to intermittent fasting diets and more personalized weight-management plans.
This story draws on original reporting from ScienceDaily.