For people with extra weight who are lifting weights and eating less, doing 5:2 intermittent fasting works just as well as cutting calories every day when it comes to getting stronger and building muscle endurance over 3 months.

What we've found so far is that 5:2 intermittent fasting appears to be just as effective as daily calorie restriction for improving strength and muscle endurance in overweight or obese adults who are doing resistance training [1]. Our analysis of the available evidence shows no difference in outcomes between the two approaches over a 3-month period. We looked at the data from one key assertion based on 52.0 supporting studies, with no studies refuting this idea [1]. This means that for people with extra weight who are lifting weights and reducing their food intake, whether they cut calories two days a week (5:2 fasting) or every day (daily restriction), they tend to gain similar levels of strength and muscle endurance. The evidence we've reviewed leans toward these two methods being equally effective for these specific goals. It’s important to note that all the evidence we’ve analyzed so far focuses on short-term results—specifically, changes seen over three months. We don’t yet have enough information to say how these approaches compare beyond that timeframe. Also, the findings apply only to people who are overweight or obese and actively doing resistance training. We can’t say if the same results would hold for people without extra weight or those not doing strength exercises. We’re still building our understanding, and our current analysis is based on a single assertion backed by a large number of supporting studies. As more data becomes available, our view may change. Practical takeaway: If you're carrying extra weight and lifting weights, cutting calories two days a week seems to work about as well as cutting a little each day when it comes to building strength and endurance over three months.