Intermittent fasting no better than typical weight loss diets, study finds

Researchers say limited eating approaches such as 5:2 diet not a ‘miracle solution’ amid surge in their popularity

Intermittent fasting is no better for shedding the pounds than conventional diets and is barely more effective than doing nothing, according to a major review of the scientific evidence.

Researchers analysed data from 22 global studies and found people who are overweight or living with obesity lost as much weight by following traditional dietary advice as when they tried fasting regimes such as the 5:2 diet popularised by the late Michael Mosley.

The approach was hardly better for weight loss than not dieting at all, the review adds, with people losing only about 3% of their body weight through fasting, far below the 5% that doctors consider clinically meaningful. The studies were all short term, looking at improvements over 12 months at most.

“Intermittent fasting is not a miracle solution, but it can be one option among several for weight management,” said Dr Luis Garegnani, the lead author and director of the Cochrane Associate Centre at the Italian hospital of Buenos Aires in Argentina. “Intermittent fasting likely yields results similar to traditional dietary approaches for weight loss. It doesn’t appear clearly better, but it’s not worse either.”

Intermittent fasting, where people restrict their eating to set hours, or fast on certain days, has soared in popularity amid claims it can help people lose weight, boost their physical and cognitive health and even slow ageing.

The Cochrane review used gold-standard techniques to analyse evidence from randomised clinical trials involving 1,995 adults across Europe, North America, China, Australia and South America. The trials examined different kinds of intermittent fasting, such as fasting every other day, the 5:2 diet where people fast for two days a week, and time-restricted eating.

Beyond the minimal benefits for weight loss, the researchers found no strong evidence that intermittent fasting improved people’s quality of life more than other diets.