Time-Restricted Eating May Make You Slightly Leaner Without Hurting Performance
You finish your morning workout, check the clock, and realize you still have a few hours before your first meal. Maybe you're intentionally fasting until noon, or maybe your schedule just works that way.
Either way, if you train regularly, you might wonder whether going that long without food could eventually affect your strength or endurance.
That's one reason researchers are taking a closer look at time-restricted eating (TRE), particularly the popular 16:8 schedule. In a recent review1, researchers examined what happens when athletes eat within an eight-hour window and fast for the other 16.
About the review
TRE focuses on when you eat rather than necessarily changing what you eat.
For athletes, though, there's an important consideration. Training requires enough food to fuel workouts, maintain muscle, and support recovery.
Researchers pooled 16 randomized trials involving 245 athletes. They compared people following a time-restricted eating schedule with those eating on a more typical schedule, looking at body weight, body fat, muscle mass, strength, endurance, power, and aerobic fitness.
A little leaner, without a performance hit
Athletes following 16:8 TRE had small reductions in body weight and body fat compared with the comparison groups. Their muscle mass didn't meaningfully change.
Performance didn't appear to suffer, either. Researchers found no meaningful differences in strength, muscular endurance, power, or aerobic fitness.
There are some caveats. Many studies were small and short, and the overall certainty of the evidence ranged from very low to moderate.
Elite athletes also appeared to have somewhat larger changes in weight and body fat than recreational athletes, but the evidence wasn't strong enough to draw firm conclusions.
Your eating window still needs to work around your workouts
The fasting window itself may not explain the changes in body composition. Eating within a shorter window can simply make it easier to consume fewer calories, which could account for some of the weight and body-fat changes.
For athletes, the bigger concern is whether an eight-hour window leaves enough room to eat and recover properly. If it makes it difficult to get enough calories or protein, or leaves you heading into workouts hungry and under-fueled, the schedule may not be a good fit.
Meal timing should also help support training. Eating enough before a workout can provide fuel, while getting protein and other nutrients afterward supports recovery. The studies in this review were too short to tell us much about the effects of consistently missing those needs.
If you want to try 16:8, keep training at the center
A shorter eating window can work for some people, but it shouldn't come at the expense of your training needs.
- Meet your nutrition needs first: Make sure you can get enough calories and protein during your eating window.
- Watch your workouts: Energy, strength, endurance, and recovery can tell you more than the scale alone.
- Remember, fasting is optional: TRE isn't necessary for improving body composition or athletic performance, and athlete-specific research is still limited.
The takeaway
For now, 16:8 eating appears compatible with maintaining exercise performance while making modest changes to body weight and body fat. Just make sure your eating window leaves enough room to properly fuel the training you're doing.