New Study Challenges Pre-Workout Carb Loading Advice

Old fitness lore would suggest that you need carbohydrates before your workout to fuel your training. Logically it makes perfect sense, as a typical workout will burn carbs as the primary fuel source.

But sometimes the mechanism in the body doesn't play out as you think it would when it comes to research. A study had 16 resistance-trained people do a hard upper-body-dominant workout. The workout consisted of 3 sets of squats, bench press, rows, and shoulder press to muscular failure at 80% of their max on three separate occasions.

Two hours before each workout, they drank one of three liquid breakfasts:

High-carb: 1.2 g of carbs per kg of body weight

Low-carb: 0.3 g of carbs per kg of body weight (same calories and protein as high carb, just less carbs/more fat)

Placebo: basically a flavored, thickened water with almost zero calories

The drinks were disguised to look, taste, and feel the same, so people mostly couldn't tell them apart. The major finding was that, among the groups, there was no meaningful difference in workout performance. Carbs made people feel fuller, but that didn't translate to better lifting.

This isn't an indictment against carbs in general, so much as a sign that the timing may not matter as much as we think. If you are eating sufficient carbs throughout the day, your muscle glycogen should be full by the time your workout comes along.

Some people may feel the need to eat something before training just because they've been told to, when in reality they feel more comfortable training on an empty stomach. This study, while small in size, is an indication that the pre-workout, carb-heavy meal is not a requirement.

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This story was originally published June 25, 2026 at 9:31 PM.