Keeping up with gym sessions can be overwhelming. You’re on for five days, resting for two, and the early morning sweat sessions can start to take a toll on your body if you’re not recovering properly.

The solution most people turn to that takes away the morning grogginess and gets you bright-eyed and ready to go is pre-workout.

The ultimate way to enhance your performance, set your body on fire, and kick fatigue to the curb.

And while pre-workout supplements have a lot to offer where performance is concerned, you hear people talking about the link between pre-workout and weight gain.

So, can pre-workout really cause you to gain weight?

This article will set the record straight. We’re talking about the side effects of conventional pre-workouts, the usual ingredients you’ll find in pre-workouts, and if pre-workout causes weight gain.

Let’s get to it.

What Is Pre-Workout?

Pre-workout supplements are all the rage where enhanced performance is concerned. Multi-ingredient pre-workout supplements (MIPS) are a special category of dietary supplements designed to be taken before exercise that consist of a mix of ingredients formulated to enhance exercise performance 1.

A 2018 review found that ingestion of MIPS can lead to acute ergogenic benefits with just a single dose, but also augment training adaptations when taken long-term and in conjunction with a training program.

For a lot of conventional pre-workouts, you’ll find some staple ingredients targeted towards reducing muscle fatigue, increasing alertness, and bolstering strength adaptations.

Common Pre-Workout Ingredients

We’re not going to dive into the specifics of each ingredient common to pre-workout supplements, but some of the most widely sought after ingredients you’ll find include:

  1. Beta-alanine: A precursor to carnosine synthesis, which is used to improve performance during high-intensity exercise; carnosine serves as an intramuscular buffer to prevent lactic acid accumulation that impairs muscle contraction 2. Supplementing beta-alanine enhances the carnosine pool and therefore may increase repetitions to fatigue and overall work capacity.
  2. Creatine: Creatine is one of the most widely consumed ergogenic aids and has been shown to enhance strength and improve body composition when combined with resistance exercise. Its ergogenic potential is derived from its ability to replenish ATP stores rapidly, allowing for a faster recovery and potential increases in training volume 3. Creatine may also be beneficial for improving lean body mass.
  3. Caffeine: Often a key component in many pre-workout supplements, caffeine offers potent stimulatory benefits and improves time to fatigue 4. Caffeine may also elicit glycogen-sparing effects during exercise to increase endurance and promote beneficial changes in body composition.
  4. BCAAs: The branched-chain amino acids are a staple in a lot of pre- and intra-workout supplements due to their role in stimulating muscle protein synthesis and increasing lean body mass. Supplementing BCAAs may also reduce muscle damage because leucine, an essential amino acid, creates a potent anabolic environment conducive to reducing protein breakdown and maintaining a positive nitrogen balance to support muscle growth 5.
  5. Nitric oxide precursors: L-arginine, L-citrulline, and nitrate are nitric oxide precursors commonly added to pre-workout supplements to support blood vessel dilation for increased oxygen and nutrient delivery to working muscles, and enhanced removal of lactic acid, wastes, carbon dioxide, ammonia, and metabolic byproducts that cause muscle fatigue and impair work capacity.

Do Pre-Workout Supplements Cause Weight Gain?

The short answer to this one is a maybe. Depending on the pre-workout formula you’re taking, they’re unlikely to cause weight gain in the form of fat mass, but the goal of any pre-workout is to improve performance and support training adaptations that facilitate better strength, power, speed, and stamina, which also usually results in muscle growth. And since muscle has weight to it, putting on a bit of mass is somewhat inevitable.

So, while fat gain may not be a common side effect, some other nasty ones can happen if you’re not careful about what you’re consuming 2:

  • Jitters
  • Nervousness
  • Irritability
  • Addiction
  • Paresthesia (pins and needles, tingles)
  • Insomnia
  • Diarrhea
  • Dehydration
  • Headaches
  • High blood pressure
  • Nausea

Long story short, running through the ingredient list will give you a good indication of whether your pre-workout may result in weight gain as a side effect. In general, there are two common culprits that can: creatine and caffeine.

Like we said before, creatine is one of the best supplements for increasing strength and improving body composition because of its role in replenishing ATP stores, thereby facilitating faster recovery and increasing training volume 2.

When creatine loading is done properly, studies show that it can increase body mass by about 1-2 kg in the first week alone 6.

In long-term studies, people supplementing with creatine generally gain about twice as much body mass and/or fat-free mass than those not taking creatine, which may result from an improved ability to perform high-intensity exercise via increased PCr availability and enhanced ATP synthesis.

Because of this, you can train harder and longer, which ultimately promotes more significant muscular hypertrophy and weight gain in the form of muscle mass.

Caffeine, on the other hand, acts in the opposite way. As a diuretic and thermogenic agent that revs the nervous system, caffeine helps you lose weight.

However, excessive caffeine consumption can be damaging to the metabolism and have the opposite effect long term. How? By affecting blood sugar levels.

In a 2017 review of the effects of acute caffeine intake on insulin sensitivity and glycemic control, several studies found that caffeine can actually increase blood glucose levels 7.

And high blood sugar also spikes insulin—an anabolic or storage hormone. Of all the roles of insulin, it’s really good at storing fat in the belly.

Keeping insulin levels high can decrease your cell’s sensitivity to insulin, which results in something called insulin resistance. In order to lose weight and keep it off, you want your cells to be insulin sensitive.

As such, caffeine has the potential to cause insulin resistance, which leads to weight gain. One systematic review and meta-analysis concluded that excessive caffeine intake can reduce insulin sensitivity in healthy subjects short term, potentially creating high blood sugar and resulting in an increased risk of metabolic dysfunction 8.

However, you have to keep in mind that the weight gain side effects of pre-workouts are dose-dependent.

If you’re creatine loading and going hard in the gym, the chances are that you’ll put on some lean muscle, whereas if you’re taking three scoops of pre-workout daily equating to upwards of 500mg+ of caffeine, then your blood sugar, nervous system, and metabolism are probably going to take a bit of a hit.

Factors That Contribute To Weight Gain

Other factors can contribute to weight gain if you’re supplementing with pre-workout daily:

1. Water Retention

Your body mass will vary depending on how much water your cells are holding on to. That’s why you’re often at your lowest in the morning, and weight progressively increases throughout the day. Pre-workout supplements can also affect water content depending on the ingredients used. For example, caffeine and creatine will alter how much water your body is holding on to.

2. Scale Mass

Your body mass comprises several different factors—muscle, air, fat, urine, blood, tissue, and neutral matter—and the relative amounts of these are going to cause your weight to fluctuate. Effects of intense workouts can increase your scale mass due to things like inflammation, post-workout hydration, and intestinal by-products.

Final Thoughts

With all of that said, a pre-workout is one of the best supplements you can add to your training stack, and despite what some people may tell you, it’s not going to cause you to gain weight directly.

However, by enhancing your performance and subsequently the results you see, weight gain in the form of increased muscle mass is a real possibility.


  1. AR Jagim, PS Harty, CL Common Ingredient Profiles of Multi-Ingredient Pre-Workout Supplements. Nutrients. 2019;11(2):254.
  2. JJ Outlaw, CD Wilborn, AE Smith-Ryan, et al. Acute effects of a commercially-available pre-workout supplement on markers of training: a double-blind study.J Int Soc Sports Nutr. 2014;11:40.
  3. J Antonio, JR Stout, D Kalman. Essentials of Creatine in Sports and Health.Humana Press, Inc, Totowa, NJ; 2008.
  4. RB Kreider, CD Wilborn, L Taylor, et al. ISSN exercise & sport nutrition review: research & recommendations.J Int Soc Sports Nutr. 2010;7:7.
  5. CP Sharp, DR Pearson. Amino acid supplements and recovery from high-intensity resistance training. J Strength Cond Res. 2010;24(4):1125-1130.
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  7. L Dewar, R Heuberger. The effect of acute caffeine intake on insulin sensitivity and glycemic control in people with diabetes.Diabetes Metab Syndr. 2017;11 Suppl 2:S631-S635.
  8. X Shi, W Xue, S Liang, J Zhao, X Zhang. Acute caffeine ingestion reduces insulin sensitivity in healthy subjects: a systematic review and meta-analysis.Nutr J. 2016;15(1):103.