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Curious about the 5:2 diet or other forms of intermittent fasting? Until recently, we had little long-term data. However, new findings show that fasting every other day delivers similar results to regular dieting.
The study, published in JAMA Internal Medicine, tracked participants over six months of weight loss and six months of maintenance. The study split 100 subjects into three groups: one third ate freely, another third had three meals a day with 75% of their daily caloric intake (1500 calories for someone eating 2000), and the fasting group alternated between consuming 25% (500 calories) and 125% (2500 calories) of their usual intake on alternate days.
After the trial, all groups maintained similar weight loss of around 5-6% (roughly 10-12 pounds for a 200-pound person). Their health markers, such as blood pressure, heart rate, cholesterol, insulin resistance, and fasting glucose, showed no significant differences.
The main difference among the groups was the dropout rate. The fasting group lost 13 of 34 participants (38%), with five leaving due to dislike of the diet. The steady-diet group had a 29% dropout rate, and the control group saw a 26% dropout. The dropout data includes participants who simply stopped following the study. Even accounting for dropouts, weight loss for those who stayed on the intermittent fasting plan may have been slightly better.
The diets ended up being more alike than expected. Participants ate more than just the provided meals, overindulged on fasting days, and ate too little on feast days. This imbalance made it hard for many to stick with the diet.
Does this study disprove intermittent fasting’s benefits? Not exactly. The study focused on “metabolically healthy” obese women, while many IF proponents argue its benefits lie in improving a broken metabolism. Additionally, the food provided was standard, carb-heavy: 55% carbs, 30% fat, and 15% protein, whereas many intermittent fasters follow a low-carb approach, prioritizing protein, fat, and fiber for most of their calories.
This is just one form of fasting. The 5:2 diet offers more time between fasting days. Another popular approach is fasting for 18 hours a day, essentially skipping breakfast and only eating lunch after fasting through the morning. We don’t yet know if these other variations are better or worse than alternate-day fasting, but you could always try them and see how it works for you.
In conclusion, intermittent fasting isn’t a miracle solution that outperforms traditional dieting. However, it may still be worth considering if you believe it could work for you.
