Does pre-workout make you gain weight?

Pre-workout supplements are multi-ingredient dietary supplements designed to boost energy, increase muscle mass and strength, aid in recovery, and generally maximize performance. They are available in pills, powders, bars, drinks, or shakes.  But alongside these performance benefits, many people share a common concern: does pre-workout make you gain weight?

Below is a closer look at what the science says about pre-workout and weight gain, plus other side effects of pre-workout to be aware of.

Yes, pre-workout can lead to weight gain in some cases — but probably not in the way most people expect. Pre-workout supplements and products may cause temporary water retention and contribute to muscle gain. While some formulations contain extra calories from sugar or other ingredients, which can nudge the scale up, many pre-workout products are low in calories.

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Water retention

Many pre-workout supplements contain creatine, a compound produced naturally in the body that helps supply energy to muscles during short, intense activity, such as sprinting or weightlifting. 

Creatine draws water into muscle cells, which can lead to an initial and temporary weight gain. This is not the same as water retention under the skin — the kind that can cause a soft or puffy appearance — because the water is stored inside the muscle cells and is not physically noticeable. The body will typically adjust to creatine’s fluid effects within the first couple weeks, and water-related weight gain should stabilize. Any additional weight gain from that point is more likely to reflect lean muscle growth.

Muscle mass increase

Muscle is often said to weigh more than fat — but what that really means is that muscle is denser than fat. As muscle builds, the body may look leaner and more toned, but the number on the scale might not change or may even slightly increase. Because many pre-workout supplements are designed to support performance and strength, they can help with harder training and muscle building over time. Any slight weight gain may actually reflect increased muscle mass, not fat gain.

Added sugars and calories

Pre-workout powders, shakes, and bars sometimes contain glucose (sugar), which can provide a quick energy boost. This makes pre-workout caloric, which can cause weight gain if the calories are not offset with physical activity.

Checking the label is a good habit — while pre-workout powders are often low in calories, some carbohydrate-heavy formulas, bars, or shakes can have 60–100 calories or more per serving.

Added artificial sweeteners

Sugar-free pre-workout supplements are unlikely to cause weight gain on their own. But some research suggests that certain calorie-free sweeteners — particularly sucralose — may disrupt appetite signals in the brain, potentially leading to increased hunger in some people. Artificially sweetened pre-workout supplements could contribute to increased calorie intake and weight gain in some people.

Stick to the recommended serving size: Taking extra pre-workout supplements will not increase performance and could lead to an excess of caffeine or calories. One serving of pre-workout per day is usually the maximum, but checking the label for the most accurate guidance is recommended. Since most formulations contain caffeine, it  is best to minimize other caffeine sources on days pre-workout is taken to avoid excess caffeine intake.

Choose low-calorie formulas: Looking for a pre-workout supplement that is low in carbohydrates and excess calories is a good starting point. Pre-workout is not necessary on rest days, and taking it unnecessarily adds calories that could contribute to weight gain.

Log your food and drinks: Research suggests that tracking daily food and drink intake can support weight loss. This is easier than ever with apps designed for the purpose. Including pre-workout in the daily log gives a more complete picture of total intake. 

Pair with consistent strength training: As muscle builds, the number on the scale may increase, but this could reflect a healthy shift. Staying consistent helps ensure that any weight changes reflect muscle gain, not fat. Paying attention to how clothes fit can also be a more reliable indicator than the scale alone.

1. Tingling sensation: Beta-alanine, an amino acid, is often included in pre-workout supplements. The ingredient can cause a harmless prickling, itching, or tingling sensation on the skin (known as paraesthesia), which is temporary and usually becomes less noticeable after a few weeks of consistent use.

2. Jitters: Pre-workout supplements almost always contain caffeine, which provides a near-instant energy boost and has been shown to increase output and reduce fatigue. Caffeine and other stimulants may cause shakiness, jitteriness, or anxiety and can lead to sleep disturbances. Starting with a half-dose can help gauge individual tolerance.

3. Skin flushing: Niacin (vitamin B3) helps to convert nutrients into fuel, but it may temporarily cause redness or warmth in the skin, known as flushing. This reaction can worsen with alcohol consumption, so it is best to avoid drinking around the time when pre-workout is taken.

4. Digestion issues: Caffeine and certain types of magnesium may have a laxative effect. Artificial sweeteners and sugar alcohols can cause bloating, gas, or an upset stomach.

5. Rapid heartbeat or increased blood pressure: Stimulants in pre-workout supplements can elevate heart rate or blood pressure in some people. Those with cardiovascular issues or sensitivity to caffeine  or other stimulants should consult a healthcare provider before taking pre-workout.

How to get rid of pre-workout side effects

Pre-workout can cause side effects, but there are strategies to manage or minimize them.

• Start small: Starting with less than a full serving of pre-workout can be helpful as the body adjusts to pre-workout.

• Stay hydrated: Staying hydrated can reduce water retention, flushing, and digestion issues, and helps combat the dehydration that sometimes comes with caffeine. Adequate water intake also supports weight management.

• Time your intake: Avoiding pre-workout in the evening can help prevent sleep disturbances. Caffeine has an average half-life of about five hours — though this varies considerably by individual — so after consuming 200 mg, roughly 100 mg may still be active in the body five hours later, which can be enough to disrupt sleep in those sensitive to caffeine. Checking the caffeine content of a pre-workout formula can help ensure it does not interfere with sleep.

• Choose your formula carefully: For those who experience anxiety, jitteriness, or a rapid heartbeat from pre-workout, caffeine-free or “low-stimulant” formulas may be worth exploring.

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Watching the scale climb while taking pre-workout can be frustrating but it is not always  cause for concern. 

• Weight gain while taking pre-workout might be due to temporary water retention or muscle gain. It is not necessarily due to increased calorie intake or fat accumulation. Paying attention to body composition rather than just the scale can provide a fuller picture. 

• To minimize unwanted weight changes, opt for low-calorie pre-workout formulas (be wary of bars and shakes that may pack a lot of calories) and track your food intake. 

• When used correctly, pre-workout can support weight management goals and help build muscle.