Major review finds intermittent fasting yields little advantage for weight loss
Updated Feb. 17, 2026 ET — A large review of clinical trials suggests popular intermittent fasting regimens produce only modest weight loss and do not clearly improve quality of life compared with traditional dieting or no treatment, raising fresh questions about the growing enthusiasm for fasting-based approaches.
What the review examined and found
Researchers pooled results from 22 randomized trials that enrolled nearly 2, 000 adults with overweight or obesity and followed participants for up to 12 months. The fasting patterns studied included time-restricted eating (limiting food intake to a daily window), alternate-day approaches and weekly fasting plans such as the two-days-per-week model.
Overall, the review found that intermittent fasting produced only small reductions in body weight—typically about 3% of baseline weight—falling short of the roughly 5% loss clinicians often regard as clinically meaningful. When compared with standard dietary advice focused on calorie reduction and healthier food choices, fasting programs delivered similar weight-loss outcomes. The review also found little to no difference in participants' reported quality of life.
Lead review author Luis Garegnani said the evidence does not support the online excitement that often surrounds fasting. "Intermittent fasting may be a reasonable option for some people, but the current evidence doesn't justify the enthusiasm we see on social media, " he said. Senior review author Eva Madrid added that clinicians should tailor advice to individual patients rather than promoting fasting as a universal fix.
Limits of the evidence and unanswered questions
Authors rated their overall confidence in the primary findings as moderate, but flagged several important limitations. Many trials were short-term, involved small numbers of participants and used variable methods, which makes it difficult to draw firm long-term conclusions. The studies included in the analysis were carried out across multiple regions, but differences in trial design and fasting regimens complicated attempts to pool results.
Investigators emphasize that intermittent fasting covers many different practices, and effects could vary by the exact timing of eating windows, the pattern of calorie restriction and participants' underlying health. Some studies suggest fasting might improve metabolic measures such as insulin sensitivity, inflammation markers and other physiologic processes linked to aging, but the current review found the evidence on those outcomes to be limited and inconsistent.
Experts also noted that many trials did not systematically assess participant satisfaction or adherence in a way that would clarify why some people succeed with fasting and others do not. One commentator highlighted the role of circadian biology, suggesting that the timing of eating relative to the body's internal clock could influence metabolic effects, but confirmed proof in humans remains sparse.
Implications for people trying to lose weight
The headline takeaway is pragmatic: intermittent fasting appears neither clearly superior nor inferior to more familiar calorie-focused diets for short-term weight loss. For some people, fasting may be a convenient or acceptable option that supports adherence to an overall calorie deficit. For others, it may reduce energy and activity or prove difficult to maintain.
Clinicians are urged to adopt an individualized approach, considering patient preferences, medical history and lifestyle. The review authors call for larger, higher-quality trials with longer follow-up that compare specific fasting strategies against standard dietary interventions and evaluate outcomes such as diabetes control, cardiovascular risk and long-term weight maintenance.
Until more definitive evidence emerges, individuals should weigh potential benefits against practical challenges and speak with a healthcare professional before beginning a fasting regimen, especially if living with chronic conditions that could be affected by changes in eating patterns.
