Should You Eat Before a Workout?
It’s a hotly debated question fitness professionals get every single day: should you eat before working out? Some say yes; some say no. Others say it depends on the type of workout. So who’s right?
Everyone. And here’s why.
The research is extensive on this topic, but it’s also slightly conflicting. The main takeaway: there are reasons to eat before a workout and there are reasons to fast before exercise. Let’s break down the when and why.
The Case for Fasting Before a Workout
If you’re an early-bird exercisers, you might prefer to run on an empty gas tank…I mean, stomach. Maybe there’s not enough time to eat beforehand, or you simply aren’t hungry that early in the morning. (I coach an Orangetheory Fitness class at 4:45 AM, so I’ve heard it all.) These are perfectly valid reasons to fast before a workout, but they aren’t the only reason. Some scientific research backs the idea of fasting, because it may have metabolic and performance benefits.
The consensus from a systemic review of 46 different studies is that fasted exercise increases circulating free fatty acids more so than fed-state exercise. This indicates a more active metabolism.1 Also, a small study of male cyclists showed that the fasted group could sustain high-intensity aerobic exercise for longer periods of time than the fed group.2
The downside is that the level of intensity is compromised. You might be able to work hard for short bouts, but you probably won’t be able to work at your maximum effort. It’s also worth noting that increased fatty acid oxidation occurs after any aerobic workout, regardless of whether you ate or not beforehand.3 Just to clarify: what the research is telling us is that fasting may increase these metabolic effects, but that doesn’t mean you don’t get the benefits if you choose to eat before a workout.
The Case for Eating Before a Workout
Speaking of eating, there’s a strong case for this pre-workout plan, as well. The same systemic review that determined the benefits of fasted exercise also found that fed-state exercise results in improved aerobic performance during long workouts.1 This seems obvious, right? You need energy if you’re going to be sweating it out for a while. Also, keep in mind, your whole body uses food to function. Eating before a workout turns on your brain as much as it feeds your muscles. If you don’t think an alert mind is necessary for a workout, chances are you’ve never face planted on a running treadmill or dropped a dumbbell on your toe.
The real question now is: what do you eat before a workout? Well, researchers have evaluated the timing and consistency of pre-workout nutrition, and here’s what we know. Carbohydrates are king. They are your main source of energy.
If you have less than one hour before your workout begins, eating a moderate glycemic meal can offer the greatest performance benefits.4 Think quick-digesting carbohydrates like a banana and peanut butter or oatmeal with blueberries. For evening exercises, you might eat several hours beforehand. In this case, you’ll want to add some healthy fats to the equation; they’ll help tide you over. Nuts, olive oil and avocado are smart options. Either way, try to eat within 1 to 4 hours prior to exercise. This will allow your body enough time to digest, so those nutrients are at the ready when it’s time to rev your engine!
References
1. Aird T.P., Davies R.W., Carson B.P. Effects of fasted vs fed-state exercise on performance and post-exercise metabolism: A systematic review and meta-analysis. Scan J Med Sci Sports. 2018;28(5):1476-1493. https://doi.org/10.1111/sms.13054.
2. Terada T, Eshghi Toghi S, Liubaoerjijin Y, Kennedy M, Myette-Cote E, Fletcher K, Boule N. Overnight fasting compromises exercise intensity and volume during sprint interval training but improves high-intensity aerobic endurance. J Sports Med Phys Fitness. 2019;59(3):357-365. doi:10.23736/S0022-4707.18.08281-6.
3. Lundsgaard AM, Fritzen AM, Kiens B. The Importance of Fatty Acids as Nutrients during Post-Exercise Recovery. Nutrients. 2020 Jan 21;12(2):280. doi: 10.3390/nu12020280.
4. Kirwan JP, Cyr-Campbell D, Campbell WW, Scheiber J, Evans WJ. Effects of moderate and high glycemic index meals on metabolism and exercise performance. Metabolism. 2001;50(7):849-855. doi:10.1053/meta.2001.24191.