Study Questions Intermittent Fasting’s Weight-Loss Edge: Review Finds Little Real-World Advantage

Groundbreaking Systematic Review Challenges Popular Diet Trend

A major new systematic review has found that intermittent fasting may make little to no difference to weight loss in adults who are overweight or living with obesity when compared with traditional dieting advice or no diet at all. The Cochrane Database of Systematic Reviews published the analysis on 16 February 2026, concluding that the much-touted eating pattern does not deliver significant weight-loss benefits above other approaches.

Intermittent fasting — which includes time-restricted eating, alternate-day fasting, and periodic fasting regimens such as the 5:2 diet — has surged in popularity over the last decade, driven in part by social media, wellness influencers and celebrity endorsements. But the new evidence now calls into question whether that hype is justified for most people.

Review Finds ‘Little to No Difference’ in Weight Loss

Researchers analysed data from 22 randomised clinical trials involving 1,995 adults across North America, Europe, China, Australia and South America, with follow-up periods of up to 12 months. Participants were predominantly overweight or living with obesity.

The review compared outcomes for people following intermittent fasting plans with those receiving traditional dietary advice — such as guidance on calorie reduction and balanced nutrition — as well as with those receiving no intervention or being on a waiting list for treatment.

The main findings showed:

• Intermittent fasting resulted in little to no difference in weight loss compared with traditional dietary advice.
• Similarly, compared with no diet or guidance, intermittent fasting likely produced little to no meaningful weight loss.
• The evidence did not conclusively demonstrate improvements in quality of life, unwanted side effects or other health outcomes due to intermittent fasting when compared to controls.

While some modest reductions in body weight were observed in individual trials, these tended to be small and often not clinically significant by common benchmarks used in obesity research.

Lead Researchers Urge Realistic Expectations

Lead author Dr Luis Garegnani of the Universidad Hospital Italiano de Buenos Aires Cochrane Associate Centre said the evidence does not support the widespread belief that intermittent fasting has a unique or superior effect on weight loss beyond the benefits of reduced calorie intake. “Intermittent fasting just doesn’t seem to work for overweight or obese adults trying to lose weight,” he said, according to the review.

Dr Garegnani also warned that the current evidence base is limited by short trial durations — mostly up to a year — and relatively small sample sizes. He stressed that obesity is a chronic condition, and short-term studies cannot reliably inform decisions about long-term strategies.

Experts Highlight Limitations and Interpretations

Independent experts who reviewed the findings noted several important considerations:

• Quality of evidence: Many of the included studies were small, with inconsistent reporting of side effects and quality-of-life measures.
• Variability of fasting regimens: Intermittent fasting encompasses a wide range of practices — from daily time-restricted eating windows to once-or twice-weekly prolonged fasts — which may not be directly comparable in trials.
• Motivation and self-selection: The trials analysed tended to involve participants assigned to fasting regimens in clinical settings. Some experts suggest that individuals who choose intermittent fasting voluntarily may be more motivated, potentially influencing outcomes in real-world practice.

Dr Adam Collins, a nutrition researcher at the University of Surrey, emphasised that while intermittent fasting may not outperform traditional diets in clinical trials, it remains one of several valid approaches to reducing calorie intake for weight management. He noted that different fasting methods may suit certain individuals better, especially when combined with personalised support.

Implications for Public Health and Diet Culture

The review’s results arrive amid global concerns about rising rates of overweight and obesity: according to the World Health Organization (WHO), adult obesity has more than tripled since 1975, with 2.5 billion adults classified as overweight in 2022 and 890 million living with obesity.

Intermittent fasting’s popularity reflects broader public interest in accessible diet strategies. However, the new review suggests that, for most adults with excess weight, simple caloric reduction — regardless of eating schedule — remains the most reliable path to weight loss.

Nutritionists and clinicians emphasise that sustainable lifestyle changes, including balanced eating, physical activity, and behavioural support, are foundational to long-term weight management and metabolic health. They also caution against overselling any single diet as a “quick fix” or miracle solution.

Future Research and Long-Term Outcomes Needed

The authors of the review and external experts both call for larger, longer-term studies to assess how intermittent fasting influences weight, metabolism and overall health beyond one year. Understanding whether certain subgroups — such as people with specific metabolic profiles — benefit more than others could inform tailored dietary recommendations.

For now, clinicians and individuals are encouraged to consider intermittent fasting as one of many tools in a broader strategy for achieving and maintaining a healthy weight, while keeping expectations grounded in the evidence.