If you’ve tried intermittent fasting, or considered it, you’re not alone. This eating pattern, which cycles between periods of fasting and eating, has gained popularity as an alternative to calorie-counting. But is it actually better?
A major new review published in The BMJ looked at nearly 100 clinical trials and found that intermittent fasting offers similar weight loss and health benefits as traditional calorie-restricted diets. One approach — alternate day fasting — showed slightly better results for weight and cholesterol, but none of the methods consistently outperformed the others by a large margin.
This doesn’t mean intermittent fasting isn’t helpful, but the results suggest it may be comparable, not superior, to traditional calorie-restricted diets.
The review analyzed data from over 6,500 adults, most of whom were classified as overweight or obese. Participants followed different forms of intermittent fasting, including:
Time-restricted eating, such as the 16:8 diet, where you fast for 16 hours and eat all your meals within an 8-hour window each day.
Alternate day fasting, which typically means eating normally one day and either fasting or eating very little the next, in an every-other-day pattern.
Whole-day fasting, such as the 5:2 diet, where you eat normally five days a week and fast or sharply reduce calories on two non-consecutive days.
All versions led to modest weight loss when compared to unrestricted eating. Only alternate day fasting showed a slight edge over traditional calorie restriction, with an average additional weight loss of about 1.3 kg (roughly 3 pounds). However, this fell short of the 2 kg benchmark used to define meaningful clinical weight loss in the study.
The researchers also found limited evidence of improved cholesterol levels, and no significant changes in blood sugar.
What’s the real takeaway? Whichever approach you can stick with may be the one that works best for you.
The researchers emphasize that all structured plans, whether fasting or not, likely help because they include planning, accountability and support. And the best strategy may not be the strictest — it’s the one you can follow consistently over time.
The study was supported by various institutions and funding organizations, including the Canadian Institutes of Health Research, German Center for Diabetes Research and USDA-backed industry groups. Full disclosures are available in the publication.