Sometimes a research paper delivers more insight than it even intended. A compared muscle gains from intermittent fasting (aka time-restricted eating) to a standard diet with no time restrictions. The intermittent fasting group utilized a 16:8 approach, which is a 16-hour fasting window and an 8-hour eating window.
Both groups did the same resistance training program 3x/week and were told to eat 300-500 calories above their daily needs. After 12 weeks, they measured the results.
The intermittent fasting group and the control group both basically gained the same amount of muscle. This is a win for intermittent fasting enthusiasts, since this style of eating was traditionally considered suboptimal for muscle gains. But here’s the interesting part: the intermittent fasting group ended up eating less than the control group.
On average, the intermittent fasting group ate at about a 200-300 calorie surplus. The control group ate around a 400-500 calorie surplus. What’s more, the control group added over double the amount of fat mass.
While the researchers’ intention was to measure muscle gain between the groups, they actually uncovered more. Since both groups gained the same amount of muscle, this indicates that perhaps we don’t need as large a calorie surplus as previously thought to optimize for muscle growth.
Granted, this was a small study with only 23 total participants. Also, it’s important to note that the intermittent fasting group trained during their eating window, so it’s unclear if these results would change if they trained fasted. This study was also done in relatively inexperienced lifters, not untrained, but not with a ton of experience either.
In the end, this study set out to test when you eat, but it ended up telling us more about how much. A 200-300 calorie surplus built just as much muscle as a 400-500 calorie surplus; the only difference was double the fat gain for double the surplus. Time-restricted eating didn’t hurt gains here, but it may have helped mainly by making it harder to overeat. If you tend to go overboard on a bulk, perhaps this is a new strategy you can implement to keep things in control.