Should You Eat Breakfast Before or After a Workout?

If you're a morning exerciser, you may have encountered the conundrum of figuring out if you should work out before or after breakfast.

Some experts suggest working out on an empty stomach is the best method, whereas others recommend eating a meal or snack that contains a balance of carbs, fat and protein (key macronutrients) prior to exercise. But a recent review in the Nutrients Journal has demonstrated that eating something before exercise can help your body achieve the most optimal workout session. Choosing the right meal or snack to eat before working out depends on many factors such as the type, length and intensity of the workout, the end goal of the workout session and, of course, your personal preferences.

(Related: What To Eat Before You Run a Race, According to Experts)

In general, eating breakfast is one of the first actions you can take towards leading a healthier lifestyle. Research has shown that eating breakfast can help stabilise blood sugar levels, which can improve athletic performance, overall energy levels, focus and mood. Without that morning meal, you may experience abrupt bursts of energy followed by dramatic dips and subsequent cravings for carb- and sugar-heavy foods throughout the remainder of the day.

As a guiding principle, it's wise to consume something with protein and a bit of fibre within 90 minutes of waking up in order to regulate blood sugar. However, for morning workouts, this goal post will shift—and that's fine.

For light to moderately intense workouts lasting one hour or less, having breakfast before the session may not be necessary. Examples of these types of workouts include yoga, Pilates, brisk walking, dance classes or leisurely riding a bike. This is a situation where a pre-workout snack or breakfast is completely up to you. Some people may feel nauseous or tired without having had some food before their workout. In this case, eating one serving of a carb-rich food (Think: a piece of fruit) should do the trick. Since fruit is digested relatively quickly, the body will be able to use those carbohydrates almost immediately for energy. Not to mention, eating one piece of fruit up to 20–30 minutes before a workout class or a home sweat-sesh shouldn't cause any gastrointestinal (GI) distress.

When it comes to more vigorous forms of exercise, such as a Long Run, a HIIT workout or weightlifting, people may need something more substantial to help them power through. For these more intense types of workouts, consider eating two servings of carbohydrates, like a piece of toast and a piece of fruit, or a peanut butter sandwich. (Pro tip: the second option includes a nice balance of the three key macronutrients!)

Are you planning to be active for more than 90 minutes? It's imperative that you eat an even larger breakfast that includes complex carbohydrates (meaning carbohydrates that contain fibre), protein and a small amount of fat, as that will help sustain energy levels during the entirety of the workout. For example, this could look like a fruit smoothie with protein powder, a Greek yoghurt parfait, overnight oats, an egg sandwich or a bowl of cereal with dairy milk. Carbohydrates are the primary fuel used during physical activity. When you exercise for longer than 60 minutes, you may need to consume additional carbohydrates during your workout to maintain those energy levels.

But again, if you're someone who likes to exercise in the morning—and the idea of eating breakfast before a workout makes you feel sick—there's no need to force that morning meal. Though it's crucial to note that hypoglycaemia (aka, when blood sugar levels drop below a healthy range) can sometimes occur when exercising while the body is in a fasted state. It's recommended to practise a fasted, moderate-intensity workout before diving into a more vigorous workout (without having food prior) to prevent hypoglycaemia, according to a 2020 review in the Journal of Sports Medicine.

As always, make sure you check with your doctor or a registered dietitian to make sure you're meeting your individual needs.

When it comes to timing when to eat before and after a workout—well, it can be confusing. If you're consuming a larger meal that includes protein, fat and complex carbohydrates, it may be wise to have that meal at least two hours before exercise in order to give the body plenty of time to digest and absorb those nutrients. Otherwise, eating a large meal right before working out can cause unwanted GI issues. A review from a 2014 issue of the journal Nutrients suggested that consuming a meal two to three hours before exercise might help support your performance and help balance blood sugar levels.

But what about if you're strapped for time and can't make a full meal a few hours before working out? Don't stress—eating something that contains carbohydrates, but is low in fibre, 30–45 minutes before a workout will probably not cause GI distress. Examples of quickly digesting carbohydrates include dried fruit, bananas, grapes, oranges, crackers and bread.

(Related: How Much Protein Do You Really Need To Build Muscle?)

What you eat after a workout is just as important as what you fuel up with before a workout. Protein should be the star of your post-workout breakfast. For those who go into a workout fasted—or only having had a single serving of carbs—consuming enough protein (between 15 and 30 grams) ideally with some fat and carbohydrates will not only help promote muscle recovery, but it will also set the stage for a regulated appetite, mood and energy levels.

After engaging in light exercise, like a gentle yoga class or a leisurely morning walk, you won't have to worry as much about eating a certain amount of protein and carbohydrates. That's just because those exercises aren't as demanding on the body; therefore, there isn't as much of a need to fuel with foods that promote muscle recovery and replenish glycogen stores (aka, fuel that's stored in the muscles and used during exercise).

However, when your main motive for exercising is to build muscle, the research isn't very conclusive with regards to what you should eat post-workout. Some research has suggested eating a meal or snack with protein within one hour after exercise is key, but there is not enough research to say that having protein one hour versus three hours after exercise is more beneficial. In general, the amount of protein needed to build muscle will depend on the person and level of exercise output. Start with a food that contains 20 grams of protein. For reference, 20 grams of protein looks like three eggs, 85 grams (approx.) of smoked salmon or one cup of Greek yoghurt.

There is much to be said about the timing of when to eat before or after a workout, as well as the type of fuel that should be consumed. In a large review and position paper on nutrient timing included in a 2017 issue of The Journal of the International Society of Sport Nutrition, the authors concluded that more research is needed to definitively determine the best times to eat and the best foods to eat for workouts. The paper also suggested that, almost more important than the "what and when to eat" before and after a workout argument, is making sure optimal amounts of protein, carbohydrates and fats are consumed throughout the entire day.

Again, consider working with an expert, such as a registered dietitian, to help create a plan that's tailored to you and your needs.

Words by Sydney Greene, MS, RDN