Figuring out what to eat, whether you’re looking to lose weight or maximize performance, is only one part of the equation. You’ve also got to tackle the question of when to eat.

Throw exercise into the mix, and the when-to-eat conundrum gets even trickier. Let’s break it down.

Young woman having a protein shake after a workoutShare on Pinterest
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There are two camps to the “to eat, or not to eat” before exercise debate.

One side avoids food before morning exercise (save for a cup of coffee because, hello, caffeine). The other gets dizzy at the mere thought of working out without a solid breakfast. Both have legit points.

Exercising on an empty stomach might make you feel lighter on your toes, and avoid the bathroom run at the gym. But eating ensures you’ve got enough fuel in the tank to make it through your workout.

But there’s more to it than personal preference. Research suggests the breakfast skippers might be onto something, though the science of it is mixed.

One study of 273 participants concluded that fat burning was higher during exercise while fasted, while insulin and glucose levels were higher when not fasted.Vieira AF, et al. (2016). Effects of aerobic exercise performed in fasted v. fed state on fat and carbohydrate metabolism in adults: a systematic review and meta-analysis. DOI: 10.1017/S0007114516003160

Generally, however, science has not given the final stamp that fasting benefits exercise, as some research shows no difference in either method.Gillen JB, et al. (2013). Interval training in the fed or fasted state improves body composition and muscle oxidative capacity in overweight women. DOI: 10.1002/oby.20379

If you can handle it, that is. The working-out-on-an-empty-stomach thing is only helpful if you can still perform during your workout. Phoning it in or tapping out halfway because you feel like you might faint won’t cut it.

How long and how hard you’re able to go depends on what and when you last ate the day before. A carb-heavy meal the night before could leave you with enough reserves to make it through your morning run.

It’s worth noting that most people will wake up slightly dehydrated from an overnight fast. Drinking a glass of water (at the very least) is a good idea for every morning exerciser.

When it comes to the eating/not eating debate, workout type matters. You might make it through an hour of yoga without stomach growls interrupting your Savasana. But you’re unlikely to make it through a 10-mile run without some kind of nutritional boost.

Longer duration endurance sports in particular have seen evidence of improvement after a high-carb meal 3 to 4 hours before.Jeukendrup AE. (2011). Nutrition for endurance sports: marathon, triathlon, and road cycling. DOI: 10.1080/02640414.2011.610348

For shorter duration workouts, the science is still mixed. The majority of research shows little difference in performance between fasted and fed exercise in workouts lasting less than an hour.Aird TP, et al. (2018). Effects of fasted vs fed-state exercise on performance and post-exercise metabolism: A systematic review and meta-analysis. DOI: 10.1111/sms.13054

Your best bet? If you know you’ll be putting in the time for a longer workout or really want to go all out, make sure you have enough energy with a small meal a few hours before.

For optimal performance, your body needs to fuel up with protein and carbs before a workout.

Carbs build up your body’s glycogen stores, which your liver and muscles release when your energy runs low. Protein helps prevent muscle damage and speed your recovery after a workout session.

Complex (aka slow-burning) carbs like oatmeal, vegetables, brown rice, and beans are best. Protein doesn’t always have to come from a cow. These healthy sources can suit everyone from carnivores to vegans:

  • eggs
  • almonds
  • chicken breast
  • nut butters
  • cottage cheese
  • Greek yogurt
  • lentils
  • quinoa

To streamline the process, build protein-carb combos like Greek yogurt with fruit, or eggs and steamed spinach on whole-grain toast. If you’re a roll-out-of-bed-and-go person without that kind of time, try a make-ahead protein shake with half of a banana.

As for timing, filling your tank 2 to 3 hours before you exercise yields maximum performance, research finds.Ormsbee MJ, et al. (2014). Pre-exercise nutrition: The role of macronutrients, modified starches, and supplements on metabolism and endurance performance. DOI: 10.3390/nu6051782

Give your body enough time to digest, especially for endurance activities like running. Undigested food in your stomach can lead to gastrointestinal issues (aka runner’s stomach or sprinting to the bathroom instead of your planned run).

Refueling and recovery are the twin goals of post-workout eating. Carbs replenish the glycogen you’ve burned off, while protein rebuilds your muscles. Aim for a ratio of 3:1 carbs to protein.Outlaw JL, et al. (2014). Effects of a pre-and post-workout protein-carbohydrate supplement in trained crossfit individuals. DOI: 10.1186/2193-1801-3-369

Take advantage of the window of recovery, which is within an hour after you finish your workout.Mohr CR. (2019). Timing your pre- and post-workout nutrition. Recharge with a smoothie, turkey and veggies on a whole-grain wrap, or yogurt with berries.

Don’t neglect fluid, which you’ll need to replace everything you sweated out at the gym. Water is always a good hydrator, but a glass of milk adds protein and electrolytes into the mix, which could help your recovery, research finds.Desbrow B, et al. (2014). Comparing the rehydration potential of different milk-based drinks to a carbohydrate–electrolyte beverage.

Remember that recovery continues 24 to 48 hours after a hard workout. So don’t neglect the nutritional value of your meals throughout the day.

Research is still super mixed with a few studies in favor of exercising on an empty stomach, so long as your workout is low to medium intensity and your goal is fat loss or maintenance.

Just be on the lookout for signs like these that your body isn’t feeling it:

  • feeling dizzy or lightheaded
  • slowing down significantly in the middle of the workout
  • losing your form
  • rapid breathing, even if the movements don’t call for it

If you’re gearing up for a more rigorous workout, eat some protein and carbs beforehand. Feeling dizzy during a set of burpees isn’t a great start to the day.

When it comes to fitness, everyone is different. It’s up to you to experiment with different pre- and post-workout foods to find what works best for you.