4 min readA new review of 22 studies found no clinically meaningful impact when comparing intermittent fasting to regular diet advice or no diet program at all. This isn’t the first study to suggest that intermittent fasting may not be as effective as once thought. Experts believe that part of the reason intermittent fasting may not work is that it can be too unrealistic to follow such rigid meal times.
A few years ago, it felt like everyone and their mom was leaning into some form of time-restricted eating to lose weight, improve energy levels, and boost overall health. While there’s now more of a focus on getting in plenty of protein and fiber, there are still some intermittent fasting diehards out there.
But while there’s some research to support the benefits of intermittent fasting, scientific data haven’t really shown this eating plan to be an effective weight-loss strategy. Now, there’s one more study to add to the list.
A new analysis of 22 randomized clinical trials found that those who followed an intermittent fasting diet didn’t lose more weight than those who followed standard diet advice or followed no specific dietary program. What’s behind this, and what does it suggest for intermittent fasting going forward? Experts break it down.
Meet the experts: Diane Rigassio Radler, PhD, study co-author and an associate professor of clinical nutrition at Rutgers University School of Health Related Professions; Caroline Fox, RDN, clinical bariatric dietitian at Tufts Medicine Weight + Wellness, Stoneham, Massachusetts
What did the study find?
The latest study, published in the Cochrane Database of Systematic Reviews, examined health and nutrition data from nearly 2,000 adults. The clinical trials featured in the study examined different types of intermittent fasting, including the popular 16:8 method, which involves fasting for 16 hours with an eight-hour eating window. Most studies followed participants for a year.
The researchers compared the impact of intermittent fasting with that of traditional diet advice, as well as with people who didn’t follow a structured program. They found no clinically meaningful impact on weight loss across any of these groups. This means people who followed standard diet advice lost the same amount of weight as those who did time-restricted eating or just did their own thing.
“Compared to regular dietary advice, intermittent fasting may result in little to no difference in percentage from baseline weight loss,” the researchers wrote in the conclusion. Researchers also found no clinically meaningful impact when comparing intermittent fasting with no intervention at all.
Why isn’t intermittent fasting great for weight loss?
This isn’t the only study to find that intermittent fasting isn’t the best approach for weight loss. A 2023 study published in the Journal of the American Heart Association analyzed data from 547 obese or overweight participants who used an app to track when they ate, what they ate, and when they slept for at least a day. Researchers found no link between following an intermittent fasting diet and weight loss.
A 2024 scientific review published in The BMJ looked at 99 clinical trials on people who were obese or overweight and found that intermittent fasting was no more effective than traditional calorie-restricted diets for weight loss.
All of these findings don’t mean you can’t lose weight on an intermittent fasting diet—it’s just that time-restricted eating isn’t helpful for most.
One potential reason intermittent fasting might backfire is that it’s not sustainable, says Caroline Fox, RDN, clinical bariatric dietitian at Tufts Medicine Weight + Wellness in Stoneham, Massachusetts.
The rigid meal timing of intermittent fasting may not align with a person’s hunger cues, and therefore lower the odds that someone will stick to it, Fox explains.
More on Intermittent Fasting
Plus, intermittent fasting still requires you to watch what you eat when you’re not fasting. “If a patient is still consuming too many calories during their eating window or eating more of their calories at night, [intermittent fasting] may ultimately not be effective for weight loss and actually promote more fat storage,” Fox adds.
Diane Rigassio Radler, PhD, co-author of the latest study and an associate professor of clinical nutrition at Rutgers University School of Health Related Professions, also notes that one of the biggest challenges she sees people face with intermittent fasting is the strict timing of the diet. Not being able to eat at very rigid times throughout the day may lead people to skip social events involving food entirely.
How to lose weight through diet
It’s important to tap into your needs when creating a diet that will work for you. “We use a patient-centered approach, tailoring a weight loss plan to their lifestyle and food preferences,” Radler says. “It is hard to come up with a one-size-fits-all.”
Fox suggests counting calories and trying to burn more than you take in. She also recommends logging your food in a journal or app to help you become more aware of what you’re eating throughout the day, and making adjustments from there.
Choosing more filling foods can be helpful, too. Research suggests that eating plenty of protein and fiber while reducing your calorie intake is also an effective way to lose weight through diet.
Ultimately, if you’re trying to lose weight and not having much success, it’s a good idea to check in with a healthcare provider. They can assess your overall health and make personalized recommendations based on that.
Korin Miller is a freelance writer specializing in general wellness, sexual health and relationships, and lifestyle trends, with work appearing in Men’s Health, Women’s Health, Self, Glamour, and more. She has a master’s degree from American University, lives by the beach, and hopes to own a teacup pig and taco truck one day.
