The popular dieting trend of intermittent fasting (IF) appears to offer no significant advantage for weight loss compared to traditional dietary approaches or even making no changes at all, according to a comprehensive new review of existing research. The findings, published in the Cochrane Database of Systematic Reviews, challenge the widespread belief that restricting when you eat is more effective than focusing on what you eat for managing weight.
For years, intermittent fasting has gained traction as a weight-loss strategy, with variations like time-restricted eating (eating within an 8-hour window) and alternate-day fasting becoming increasingly common. Proponents suggest that IF can improve metabolic health and simplify dieting. However, this latest analysis casts doubt on those claims, suggesting that the perceived benefits may be largely attributable to overall calorie reduction, rather than the timing of meals.
The review, analyzing data from 22 randomized controlled studies involving nearly 2,000 adults across multiple continents, found that intermittent fasting resulted in weight loss comparable to that achieved through conventional dietary advice, such as reducing calorie intake or modifying food choices. Crucially, when compared to a control group receiving no dietary advice, intermittent fasting showed no discernible benefit in terms of weight loss. “Intermittent fasting just doesn’t seem to work for overweight or obese adults trying to lose weight,” stated Luis Garegnani, a researcher at the Italian Hospital of Buenos Aires in Argentina, in a press release as reported by New Scientist.
What the Research Examined
Researchers evaluated the impact of various intermittent fasting methods – including time-restricted feeding, periodic fasting, and alternate-day fasting – against traditional dietary advice and a no-intervention control group. The studies included participants aged 18 to 80 who were either overweight or obese. The primary outcome measured was weight loss, but the review as well considered quality of life and potential adverse effects, such as fatigue, headache, and nausea. The Cochrane review noted that the evidence regarding quality of life and unwanted events was less certain.
A separate meta-analysis, published in July 2025 in Nutrition Journal, also investigated the effects of intermittent fasting on body composition and cardiometabolic outcomes. This study, encompassing 15 randomized controlled trials with 758 overweight or obese adults, found that IF significantly reduced body weight (by an average of 3.73 kg) and body mass index (BMI). However, it’s important to note that this study compared IF to various control diets, and did not definitively establish superiority over other weight management strategies. Read the full study here.
Limitations and Future Research
The researchers emphasize that the included studies did not consistently report on participant satisfaction with intermittent fasting, nor did they assess its impact on diabetes status or other health conditions. This highlights a gap in the current understanding of IF’s broader health effects. The Cochrane review specifically points to the necessitate for further research to investigate these areas.
It’s also important to consider that individual responses to dietary interventions can vary significantly. Factors such as genetics, lifestyle, and underlying health conditions may influence the effectiveness of intermittent fasting. The current evidence suggests that IF is not a universally superior weight-loss method, and individuals considering this approach should consult with a healthcare professional to determine if it’s appropriate for their specific needs.
As obesity rates continue to rise – projected to affect over 1.53 billion adults by 2035 – research into effective weight management strategies remains crucial. While intermittent fasting may offer benefits for some, the current body of evidence suggests it’s unlikely to be a magic bullet for weight loss. Future studies will need to address the limitations of existing research and explore the long-term effects of IF on various health outcomes.
What remains clear is that sustainable weight management requires a holistic approach that encompasses a balanced diet, regular physical activity, and personalized support.
Disclaimer: This article provides informational content and should not be considered medical advice. Please consult with a qualified healthcare professional for personalized guidance on weight management and dietary choices.
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