Intermittent fasting has taken the nutrition world by storm, with countless people embracing its various forms in hopes of shedding pounds and improving their health. But a sweeping new review published in the Cochrane Database of Systematic Reviews on February 16, 2026, is throwing cold water on the hype. According to a comprehensive analysis of 22 randomized controlled trials spanning North America, Europe, China, Australia, South America, and Brazil, intermittent fasting offers little to no advantage over traditional dietary advice—or even no intervention at all—when it comes to weight loss for adults with overweight or obesity.
The review, conducted by an international team of researchers and summarized by outlets including BBC and The Conversation, pooled data from nearly 2,000 adults classified as overweight or obese (with a BMI of 25 or higher). The studies covered a range of intermittent fasting strategies, including time-restricted feeding (such as the popular 16:8 diet), periodic fasting (like the 5:2 diet), alternate-day fasting, and modified alternate-day fasting. All interventions lasted at least four weeks, with most focusing on outcomes up to 12 months.
So, what did the researchers actually find? When intermittent fasting was pitted against regular dietary advice—think calorie restriction or structured eating plans—the difference in weight loss was minuscule. Across 21 studies with 1,430 participants, intermittent fasting resulted in a mean difference of just -0.33% from baseline body weight. The evidence was rated as low certainty, meaning there’s still some wiggle room for doubt, but the numbers are clear: both approaches led to similar outcomes.
For those hoping for a more dramatic result, the numbers don’t get much better. In four studies with 472 participants, the proportion of people achieving at least a 5% reduction in body weight was nearly the same for intermittent fasting and conventional dieting. Again, the certainty of the evidence was very low, but the message is consistent.
Quality of life, often an overlooked aspect in weight loss research, was also measured using validated tools like the Assessment of Quality of Life-8D, SF-36, and RAND-36 surveys. Across three studies with 106 participants, there was little to no difference between intermittent fasting and standard dietary approaches. In other words, fasting didn’t make people feel better—or worse—than traditional diets did.
What about doing nothing at all? The researchers didn’t shy away from this comparison. In six studies with 427 participants, intermittent fasting led to a mean difference of -3.42% weight loss from baseline compared to no intervention or waiting list controls. While this might sound promising, the review authors described this as moderate-certainty evidence that is likely not clinically meaningful. In fact, a 3% difference in weight loss is generally not considered enough to make a real-world impact, as reported by The Conversation.
Adverse events—those pesky side effects that can make or break a diet—were also scrutinized. Reported issues included nausea, headache, dizziness, hunger, constipation, diarrhea, dyspepsia, cold intolerance, irritability, insomnia, and impaired concentration. The review found little to no difference in adverse events between intermittent fasting and regular dietary advice, though the evidence here was very uncertain. Notably, subgroup analyses suggested that modified alternate-day fasting and alternate-day fasting might be linked to higher rates of adverse events compared to time-restricted feeding. And while studies in high-income countries showed increased adverse events with intermittent fasting, a single study from a low- or middle-income country suggested fewer problems—though the authors cautioned that the small number of studies limits any firm conclusions.
Despite the lackluster results for weight loss, the review authors and outside experts offered some important caveats. Dr. Luis Garegnani, the lead review author from Universidad Hospital Italiano de Buenos Aires, told BBC, "Intermittent fasting may be a reasonable option for some people, but the current evidence doesn't justify the enthusiasm we see on social media." Senior review author Eva Madrid echoed this sentiment, emphasizing that doctors should take a case-by-case approach when advising overweight adults on weight loss strategies.
Others weighed in on the gap between public perception and scientific evidence. Dr. Baptiste Leurent, associate professor in medical statistics at University College London, remarked, "This is yet another example of a misalignment between public perception and the scientific evidence." Professor Keith Frayn, emeritus professor of human metabolism at the University of Oxford, was even more blunt: "This study shows that such claims can have little relevance," he said, referring to the supposed metabolic magic of intermittent fasting. For those hoping for a quick fix, Frayn added, reducing calorie intake remains the tried-and-true method.
Still, intermittent fasting isn’t without its potential upsides. Although the review focused on weight loss and quality of life, other studies have linked intermittent fasting to benefits like lower blood pressure, improved fertility, reduced incidence of metabolic syndrome, and even changes in metabolism that might restrict cancer development. A 2024 study found possible metabolic and gut changes that could hinder cancer growth, while research from 2025 suggested benefits for shift workers’ metabolic health. However, as The Conversation noted, these findings are preliminary and more research is needed to confirm any long-term health advantages.
The review also highlighted significant gaps in the evidence. For one, none of the included studies reported on participant satisfaction, diabetes status, or overall comorbidity measures. Most studies were conducted in high-income countries, with only one from a low- or middle-income setting. Furthermore, seven studies were exclusive or predominantly women, and just one focused on men, leaving plenty of questions about how intermittent fasting might affect different populations. And with most trials lasting only up to 12 months, the long-term effects remain largely unknown.
For those considering intermittent fasting, the takeaway is clear: it’s not a miracle cure for weight loss, but it may still be a reasonable option for some, provided it fits with personal preferences and can be sustained over time. As the review authors put it, "Physicians and patients may need to evaluate willingness and readiness to implement intermittent fasting as a treatment strategy, based on individual practicality and sustainability." And as always, consulting a healthcare professional before embarking on any new diet—especially for those with underlying health conditions—is a wise move.
With the debate around intermittent fasting likely to continue, one thing is certain: weight loss remains a personal journey, and no single approach works for everyone. The evidence, for now, suggests that the best diet is the one you can stick to—no matter how you slice it.