Train fasted or fed?

A recent study performed by the University of Bath in the U.K. explored the question whether it’s better to eat before exercise or workout on an empty stomach. Gym goers and fitness bloggers have had strong opinions on each but is one really beneficial over the other?

A small group of ten “healthy overweight” men ages 18-35 were recruited to test the effects of exercising on an empty stomach and whether it benefited the body when it comes to getting rid of unwanted fat, (adipose tissue) with an emphasis on banishing abdominal subcutaneous adipose tissue (dangerous belly fat). They were asked to exercise by walking at a moderate pace (60% of maximum oxygen uptake) for 60 minutes. Scientists measured their blood at various times during and after exercise as well as their actual body fat (adipose tissue).

They were given a meal 2 hours before exercise of mostly carbohydrates which included white bread, corn flakes, sugar, jam, and low fat milk.

The group was tested in both fed and fasted exercise conditions 3-4 weeks apart and there seemed to be substantial differences between both tests.

It was discovered that fasted exercise had significant benefits due to increased fat oxidation—using your body fat for fuel as shown in this table below:

As previously believed, eating a carb-rich meal an hour or two before exercise fuels your workout, allowing you to perform more but preventing you from burning your own body fat for energy. If you want to perform better as in a competition, you’d be better off eating an hour or two before exercise. But if your goal is to get rid of some body fat, then fasted exercise is the way to go.

NOTE that this only takes into account “moderate intensity exercise” meaning that which is no greater than 60% VO2 max. This would be a light jog or stationary bike ride where you can still have a conversation without gasping for air. Any more strenuous than that and your body insists on using available carbs for energy because they are a quick response energy source.

It is still recommended to consume a small meal that includes protein and carbs (but not necessarily fats) an hour or two before a strenuous workout such as a weight lifting workout like the ones we emphasize here, or a HIIT workout (High Intensity Interval Training) workout.

We at 10in30 Fitness have been instructing readers of our book to run daily on an empty stomach in the evening right before dinner at a moderate pace for only 20 minutes. For our quick, 12 minute morning workout we recommend having something small like 1 slice of toast or a yogurt and/or coffee for the caffeine if you count on it to get your morning started.

You can read more here:

American Physiological Society (APS). “To eat or not to eat (before exercising): That is the question.” ScienceDaily. ScienceDaily, 6 April 2017. read
Actual study here:

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