Should You Eat Before or After You Exercise?

Whether it’s steady state vs. HIIT cardio or powerlifting vs. bodybuilding, everyone has an opinion when it comes to working out. One of the most hotly contested topics might be whether you should eat before or after you exercise.

Well, science has found the answer.

A group of researchers from the Universities of Bath, Birmingham, Newcastle and Stirling conducted a study to analyze the energy expenditure of 12 healthy, physically-active men between the ages of 20 and 26. To determine the effect of pre-workout nutrition, the men had to complete three different trials.

First, they had to consume a breakfast of oats and milk, followed by no exercise. In the second trial, they had to eat the same meal two hours before cycling for 60 minutes. Finally, they skipped the meal altogether and had to complete the 60-minute cycling period.

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Interestingly, the results showed that when the men conducted the workout on an empty stomach, they had a greater calorie deficit throughout the day – about 150 calories – meaning the fasting workout was optimal for losing weight. Based on the results of their experiment, the authors concluded that for healthy, young men, a short-term energy deficit can be obtained by skipping breakfast before exercising.

But how exactly does that work?

By skipping a pre-workout meal, your body must rely on other sources for energy, such as stored body fat. Exercising in a fasted state is more effective at burning body fat and can help you lose weight more quickly.

Dr. Phoenyx Austin, a certified Sports Medicine Specialist, explained another benefit of fasted exercise: insulin control.

“When insulin is elevated—as is the case after you eat—your body will be in a state of wanting to store fat, not burn it. It doesn’t matter if you exercise like a mad man after a meal, you won’t be able to burn body fat until insulin levels drop, which can typically take two-to-three hours, if not longer.”

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There are, of course, two sides to every story – for those who do enjoy eating before exercising, the case isn’t closed. The study also revealed that the men who ate breakfast first burned more carbohydrates overall during the workout, and they also experienced a metabolism boost later on in the day.

Science can give you the tools to succeed, but remember: the choice is really up to you.