Intermittent fasting may help some people lose weight without relying as heavily on constant food restriction.
People who repeatedly lose weight and regain it may do better with intermittent fasting than with traditional calorie counting, according to new findings.
A study from Adelaide University examined the psychological effects of intermittent fasting and calorie restriction, comparing how each approach affected eating behaviors, mood, sleep and quality of life.
Both diets produced similar weight loss, but participants following intermittent fasting did not feel they had to make major changes to their eating behaviors, such as closely watching for overeating or counting calories, to lose weight.
The calorie restriction group had a different experience. Those participants said they had to consciously focus on limiting how much they ate and avoiding overeating. That increased sense of control explained 15% of their weight loss.
Fasting may feel less restrictive
“While many diets can result in weight loss, they may be difficult to stick to, and this makes keeping that weight off long-term more challenging,” said Professor Leonie Heilbronn from Adelaide University’s School of Medicine and the South Australian Health and Medical Research Institute.
“The results of our study indicate intermittent fasting could offer an alternative pathway for people who find conventional dieting challenging.”
Trial compared three approaches
The 18-month trial included more than 200 people with obesity. Participants were assigned to one of three groups: intermittent fasting, continuous calorie restriction or standard care.
Those in the intermittent fasting group ate 30% of their energy needs between 8 am and 12 pm on three nonconsecutive days each week, followed by a 20-hour fast. On days when they were not fasting, they could eat their usual diet.
Participants in the calorie-restricted group ate 70% of their usual diet. Those in the standard care group continued with standard diets but received healthy eating guidelines.
After six months, people in both the intermittent fasting and calorie-restricted groups had lost about seven kilograms, compared with about two kilograms in the standard diet group. Participants also reported improvements in depression and wellbeing, including on fasting days.
Weight loss may follow different paths
The findings, published in Clinical Nutrition, suggest that calorie restriction and intermittent fasting may support weight loss through different psychological and behavioral routes.
“Psychological and behavioral effects have a major influence on people’s abilities to adhere to diets. Intermittent fasting may help people achieve weight loss through ways that are less dependent on consciously restricting intake,” said Professor Heilbronn.
Although intermittent fasting has grown in popularity, its long-term psychological and behavioral effects are still not well understood compared with more traditional dieting methods.
“Future trials should be designed to identify individuals who struggle to improve eating behaviors, as they may do better with intermittent fasting diets, enabling more personalized weight management,” said Professor Heilbronn.
Reference: “Exploring the impact of intermittent fasting plus time-restricted eating versus calorie restriction on eating behavior, mood, sleep, quality of life in adults with obesity” by Xiao Tong Teong, Kai Liu, Andrew D. Vincent, Gary A. Wittert, Amy T. Hutchison and Leonie K. Heilbronn, 15 May 2026, Clinical Nutrition.
DOI: 10.1016/j.clnu.2026.106686
This work was supported by the National Health and Medical Research Council Project Grant (APP1143092). XTT was supported by an Australian Government Research Training Program Scholarship from The University of Adelaide.
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