All psyched up for that killer session in the gym? Having explosive energy is key, but eating the wrong foods too close to go-time can really ruin your workout and set your training back in a big way.

“Putting the wrong things in your tank before you exercise can leave you lethargic, crash your system, or cause wicked cramps,” says Jim White, R.D., a spokesperson for the Academy of Nutrition and Dietetics. “And going on empty can do the same.”

So don’t doom your cardio or weight session before it even starts. Here, the biggest pre-workout diet mistakes many men make—and why you should avoid them.

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