Intermittent fasting has become something of a celebrity darling and social media sensation in recent years, with countless influencers touting its supposed power to melt away pounds without the drudgery of calorie counting. From Jennifer Aniston to Hugh Jackman, the '16:8' fasting plan – where eating is restricted to an eight-hour window each day – has found famous fans and everyday devotees alike. But does the science really back up the hype?
According to a major new review published in the Cochrane Database of Systematic Reviews and reported by The Independent and Delta News TV, the answer is a resounding "not really." Researchers analyzed 22 randomized clinical trials involving 1,995 adults from North America, Europe, China, Australia, and South America. The studies looked at various forms of intermittent fasting, including alternate-day fasting, periodic fasting, and time-restricted feeding, with most participants being followed for up to 12 months.
What did they find? In short, intermittent fasting did not lead to greater weight loss for overweight or obese adults than traditional dietary advice or even doing nothing at all. The findings, which directly challenge the breathless enthusiasm found on social media, suggest that simply changing when you eat is not the magic bullet for weight loss that many had hoped.
"Intermittent fasting just doesn’t seem to work for overweight or obese adults trying to lose weight," said Professor Luis Garegnani, lead author of the review from the Universidad Hospital Italiano de Buenos Aires Cochrane Associate Centre, as quoted by Delta News TV. He added, "Intermittent fasting may be a reasonable option for some people, but the current evidence doesn’t justify the enthusiasm we see on social media."
Obesity remains a massive global health challenge, and the numbers are sobering. According to the World Health Organization, obesity has more than tripled worldwide since 1975. In 2022, 2.5 billion adults were overweight, with 890 million of those living with obesity. In England alone, more than two-thirds of adults are estimated to be overweight or obese. The health consequences are dire: being overweight or obese is now the leading cause of cancer after smoking, linked to at least 13 different types of the disease.
Given the scale of the problem, it's easy to understand why so many people are eager for a simple solution. Intermittent fasting, with its promise of hacking biology and sidestepping the tedium of calorie tracking, has been especially appealing. But the findings from the Cochrane review pour cold water on the idea that fasting windows alone lead to meaningful weight loss.
Kim Pearson, a nutritionist specializing in weight loss, explained to The Independent that while intermittent fasting can help some people reduce their calorie intake, improving overall diet quality is far more likely to help with lasting weight loss. "More aggressive approaches are often difficult to sustain and do not address the root causes of weight gain, such as poor diet quality, excess ultra-processed foods and blood sugar instability," she said. Instead, Pearson recommends focusing on eating more protein, fiber, and healthy fats while cutting back on ultra-processed foods, sugar, and refined carbohydrates. "This helps regulate appetite naturally, supports stable blood sugar and allows the body to burn stored body fat more efficiently," she added.
Rob Hobson, registered nutritionist and author of the low appetite cookbook, echoed these sentiments. He warned that restrictive fasting windows or very low-intake days can lead to compensatory overeating, low energy, or simply not being sustainable over the long term. "It’s long-term consistency that really drives results when it comes to weight loss," Hobson told The Independent. In other words, a diet that can't be maintained is unlikely to produce lasting results – no matter how trendy it might be.
Dr. Earim Chaudry, chief medical officer at the online pharmacy Voy, went a step further, noting that weight loss isn't simply a matter of willpower. While fasting might help in the short term, he said, "Limiting eating windows does not address the biological drivers of appetite, metabolic adaptation and weight regain, and it is often difficult to sustain." For many, the allure of intermittent fasting lies in its simplicity, but as Dr. Chaudry suggests, true and lasting weight loss is rarely that straightforward.
The review also highlighted some limitations in the current body of research. Reporting of side effects was inconsistent across the 22 trials, making it hard for scientists to draw firm conclusions about the safety or potential downsides of intermittent fasting. Moreover, most of the studies enrolled predominantly white people in high-income countries, even though obesity is a rapidly growing issue in low- and middle-income nations. That means the findings may not be universally applicable – a point not lost on the researchers themselves.
Professor Eva Madrid, senior author of the review from the Cochrane Evidence Synthesis Unit Iberoamerica, told Delta News TV, "With the current evidence available, it’s hard to make a general recommendation. Doctors will need to take a case-by-case approach when advising an overweight adult on losing weight." This individualized approach is echoed by many experts who stress that no single diet works for everyone and that personal preferences, lifestyle, and medical history should all be taken into account.
Interestingly, while the review found no meaningful difference in weight loss between intermittent fasting and traditional diets, some experts acknowledged that there may be minor benefits to fasting. Pearson noted that not eating overnight for 12-14 hours "aligns with our circadian biology and gives the body time to move out of a constant fed state." However, she was quick to add that there is no need for extreme fasting, and that moderate, sustainable approaches are usually best.
So where does all this leave the millions of people hoping for a shortcut to weight loss? The evidence suggests that, while intermittent fasting isn't harmful for most people, it's not a miracle cure either. The real key, it seems, is improving the overall quality of the diet, focusing on whole foods, and building habits that can be maintained for the long haul. As Professor Garegnani put it, "Obesity is a chronic condition. Short-term trials make it difficult to guide long-term decision-making for patients and clinicians."
The bottom line: if you're considering intermittent fasting, it may be worth a try – but don't expect it to work magic. Sustainable changes to what and how you eat remain the cornerstone of effective weight management. And as always, it's wise to consult with a healthcare professional before making major changes to your diet or lifestyle.