does pre workout break a fast

Does Pre-Workout Break a Fast?

If 2022 is the year you decided to get your fitness on point, you may have started intermittent fasting and going to the gym recently. Or you’re veteran by now and you just have some questions about pre workout.

Pre workout is one of the top selling supplements you can buy. This is because it works. The caffeine in pre workout, combined with the other ingredients in these supplements lead to increased energy, better focus, and improved blood flow. If you’re working out fasted, this means you won’t have a pre workout meal to fuel your training, so pre workout may be just what you need.

In case you don’t know intermittent fasting (or time-restricted eating) is when you set an interval every day to consume no food, and a shorter interval in which you can eat. The most popular intermittent fasting protocol is 16 hours fasting, followed by an 8 hour eating window. During your fasting period, you should avoid food and any calories.

Does Pre Workout Break a Fast?

Generally, pre workout does not contain calories, so it does not break a fast. However, not all pre workouts are sugar free or calorie free, so you should check your supplement’s label. If you’re intermittent fasting, you will want a pre workout with no sugar and no calories. Pre workout (even if it does contain calories) probably won’t cause any significant weight gain.

Video: Do Pre-Workouts, BCAAs and Other Supplements Break a Fast?

Note About Artificial Sweeteners

If you’re strict about your fasting, you may avoid artificial sweeteners as well — and in this case you may need to think about substituting black coffee for your pre workout. While artificial sweeteners won’t necessarily break a fast, there are other negative health benefits that you may need to consider. According to the Indian Department of Pharmacology, “animal studies have convincingly proven that artificial sweeteners cause weight gain, brain tumors, bladder cancer and many other health hazards.” In addition, sugar alternatives may actually lead to an increased risk of obesity and diabetes.

Pre Workout Ingredients That Won’t Break A Fast

The main active ingredients in pre workouts don’t contain calories, so you can still get the benefits without breaking your fast. These are the primary ingredients in most pre workout supplements.

Source: Nutricost Pre Workout Formula

The Ingredients in Pre Workout are Fasting-Friendly

  • B Vitamins: B-vitamins, like Vitamin B12, are included in pre workouts to provide a boost in energy and to improve your body’s metabolic function to absorb energy from macronutrients.
  • L-Citrulline Malate: Citrulline is an amino acid that helps increase the body’s production of nitric oxide. This helps boost blood flow for better muscle pumps, and helps the body get rid of lactic acid more efficiently.
  • Beta-Alanine: Beta-alanine is a non-essential amino acid that is involved in the body’s production of carnosine. Carnosine acts as an antioxidant and can help prevent muscle soreness and inflammation. Beta-alanine is great for endurance activities lasting longer than one minute. It’s also the ingredient in pre workout commonly associated with the tingling or itchy feelings some people get from pre workout.
  • Taurine: Taurine is a compound found naturally in meat, fish and dairy products. It’s commonly used as a dietary supplement, and as an additive in pre workout and energy drinks. The research on taurine is mixed, but one study found that supplementing with taurine may improve exercise capacity.
  • L-Theanine: L-theanine is a compound found in green tea and some mushrooms. It is used for treating anxiety, stress, and other conditions but these uses aren’t backed by strong scientific evidence. When combined with caffeine, l-theanine can help minimize some of the jitters and anxiety that too much caffeine may cause.
  • Caffeine: Caffeine is the main driver of results for most pre workouts. Consuming caffeine before training can give you a burst of energy, improved focus, and increased motivation. Another benefit of caffeine is that it can help reduce rate of perceived exertion, which can make harder efforts seem easier.

What is Pre-Workout?

Pre workout is any supplement that is designed for taking prior to a workout to improve athletic performance. The active ingredients vary from one brand to another. Generally, they will contain some mix of caffeine, beta-alanine, and other vitamins. The purpose of pre workout is to increase energy levels, focus, and blood flow.

What is Fasting?

Fasting means you stop eating completely for a period of time. Fasting can be done for a number of reasons including religious practices, calorie restriction, or weight loss. One of the more popular fasting protocols is called intermittent fasting where you fast for a set period of time during the day and restrict your eating to a shorter period of time within your waking hours.

Read More: The Best Pre Workouts with Zero Calories


  1. Tandel KR. Sugar substitutes: Health controversy over perceived benefits. J Pharmacol Pharmacother. 2011 Oct;2(4):236-43. doi: 10.4103/0976-500X.85936. PMID: 22025850; PMCID: PMC3198517.
  2. Guo Z, Cai J, Wu Z, Gong W. Effect of High-Intensity Interval Training Combined with Fasting in the Treatment of Overweight and Obese Adults: A Systematic Review and Meta-Analysis. Int J Environ Res Public Health. 2022 Apr 12;19(8):4638. doi: 10.3390/ijerph19084638. PMID: 35457507; PMCID: PMC9030367.
  3. Artificial Sweeteners May Change Our Guy Bacteria in Dangerous Ways, Scientific American. 2015 Apr 1.
  4. Doherty M, Smith PM. Effects of caffeine ingestion on rating of perceived exertion during and after exercise: a meta-analysis. Scand J Med Sci Sports. 2005 Apr;15(2):69-78. doi: 10.1111/j.1600-0838.2005.00445.x. PMID: 15773860.