Daijiworld Media Network – London
London, Feb 16: Intermittent fasting is no more effective for weight loss than conventional calorie-controlled diets and offers only modest benefits compared to doing nothing at all, according to a major global review of scientific studies.
Researchers analysed data from 22 randomised clinical trials involving 1,995 adults across Europe, North America, China, Australia and South America. The review, conducted by the Cochrane collaboration, found that people who are overweight or living with obesity lost similar amounts of weight whether they followed intermittent fasting plans or traditional dietary advice.
Participants who practised fasting regimes — including alternate-day fasting, time-restricted eating and the popular 5:2 diet promoted by the late Michael Mosley — lost around 3 per cent of their body weight on average. Doctors generally consider a 5 per cent reduction to be clinically meaningful. Most of the studies tracked participants for up to 12 months.
“Intermittent fasting is not a miracle solution, but it can be one option among several for weight management,” said Dr Luis Garegnani, lead author of the review and director of the Cochrane Associate Centre at the Italian Hospital of Buenos Aires in Argentina. “It likely yields results similar to traditional dietary approaches. It doesn’t appear clearly better, but it’s not worse either.”
Beyond modest weight loss, researchers found no strong evidence that intermittent fasting improved quality of life more than other diets. Many of the studies were short-term and varied in quality, making it difficult to draw firm conclusions about long-term health benefits.
Intermittent fasting — which involves restricting food intake to certain hours of the day or fasting on specific days — has grown in popularity amid claims it can improve physical and cognitive health, enhance metabolism and even slow ageing.
Dr Zhila Semnani-Azad of the National University of Singapore said the impact of fasting may depend on timing, given the close link between circadian rhythms and metabolism. Animal studies suggest fasting may improve insulin sensitivity, reduce inflammation and oxidative stress, and trigger autophagy — the body’s internal recycling process linked to ageing and longevity. However, she noted that the lack of a universal definition of intermittent fasting complicates efforts to evaluate its true effects.
Maik Pietzner, professor of health data modelling at the Berlin Institute of Health at Charité, said he was surprised the weight loss difference compared to no diet was so small, though the findings align with evidence that people may reduce physical activity while fasting. He added that significant biological changes may require longer fasting periods, citing research showing measurable protein changes in blood only after several days of complete fasting.
“If people feel better on such diet regimens, I wouldn’t stop them,” Pietzner said. “But there is no robust evidence for positive effects beyond a possible moderate weight loss. Our bodies can cope well with food scarcity, but that doesn’t necessarily mean we perform better because of it.”
The authors stressed that while intermittent fasting can be a viable option for some individuals, it should not be viewed as superior to balanced, sustainable dietary approaches for long-term weight management.