A large international review suggests that intermittent fasting may not lead to meaningful weight loss for people who are overweight or obese. Researchers found that popular fasting methods often make little to no difference when compared with standard dieting advice or even no advice at all.
The study reviewed 22 clinical trials involving nearly 2,000 adults. It examined short term fasting plans lasting up to 12 months. These plans included approaches like the 5:2 diet, time restricted eating within an eight hour window, and alternating between normal eating days and very low calorie days.
What the Review Found
Researchers compared intermittent fasting with traditional calorie controlled diets and general healthy eating advice. The results showed no significant difference in weight loss or quality of life between the groups.
When compared with people who received no dietary advice, intermittent fasting also showed little to no added benefit. However, the impact on quality of life in that comparison remains unclear.
Lead author Luis Garegnani from Universidad Hospital Italiano de Buenos Aires said social media has created unrealistic expectations around fasting. He explained that current evidence does not support the strong enthusiasm seen online.
Senior review author Eva Madrid added that doctors should guide patients individually. Some people may respond better than others, so weight loss advice should depend on personal health needs.
Study Limitations Raise Questions
The researchers noted several weaknesses in the available data. Many of the studies involved small groups and did not follow the most rigorous research methods. Because of this, experts say the findings should be interpreted with caution.
The review appeared in the Cochrane Database of Systematic Reviews. The authors called for more long term research. They want to explore how intermittent fasting affects people with type 2 diabetes and other health conditions. They also stressed the need to study differences based on gender, body mass index, and geographic background.
The trials took place across Europe, North America, China, Australia, and South America.
Experts Warn Against Weight Loss Hype
Baptiste Leurent from University College London said the combined evidence clearly shows limited benefit. He described the findings as another example of how public perception often differs from scientific proof.
Keith Frayn, emeritus professor at University of Oxford, said many claims about fasting focus on so called special metabolic effects. He stated that this review does not support those claims. According to him, sustainable weight loss still depends on reducing overall calorie intake.
Weight Loss Injections Remain Popular
While debate continues around fasting, around 1.6 million adults in the UK use weight loss injections such as Wegovy and Mounjaro. Most people buy these privately rather than through the NHS.
Recent research shows that people who stop these injections may regain weight faster than those who stop traditional dieting and exercise plans.
