In general, eating some combination of protein and carbohydrates before a workout to sustain energy and build muscle is advised, says Kate Patton, RD, who specializes in sports nutrition at Cleveland Clinic in Ohio. Foods with a high amount of fat or fiber, on the other hand (think broccoli or a grilled cheese sandwich), should be avoided, as they may cause stomach upset and cramping.
But what you should eat before a 30-minute power walk is going to look different from what you eat before a 20-mile training run. Here’s what you need to know.
If you’re exercising for less than an hour, first thing in the morning, McDaniel and Patton agree there’s no need to eat. Indeed, there may be a benefit to not eating before early morning workouts that aren’t too intense.
“If you have an early workout that’s easy or light and you’re trying to lose weight, it might be best to have a glass of water but skip the food,” says McDaniel, noting that this encourages your body to burn a greater percentage of body fat to fuel your workout. Research has found that people may burn more fat over the course of 24 hours if they work out before eating breakfast compared with exercising later in the day, according to a study published in the December 2015 issue of the journal EBioMedicine. (2)
But if you’re ravenous when you wake up, you may need some food in your stomach before activity. Signs that you’re too hungry to run on empty include intolerable hunger pains, headache, light-headedness or dizziness, irritability, or inability to concentrate, says Patton.
In these cases, even if you have just 10 to 15 minutes before your workout, eat a small amount of quickly digestible carbohydrates, such as 4 ounces of fruit juice, a small banana, a handful of grapes, or a handful of dry cereal to ensure you have the physical and mental energy to get moving. Other data suggests this type of small, carb-rich snack (or even a somewhat larger 200-calorie snack) may also enhance feelings of relaxation after your workout, making you that much more likely to stick with it, according to a July 2015 study published in the journal Nutrients. (3)
If you’re exercising for more than an hour first thing in the morning, you should always eat a small amount of easy-to-digest carbs — like the options mentioned above — so you have the necessary energy to sustain your workout, Patton says. If you’re waking up at least 30 minutes before your workout, you’ll have enough time to digest an even more substantial snack of around 200 calories. (Think a light breakfast, such as half an English muffin with a tablespoon of peanut butter and a few banana slices, an apple with a tablespoon of almond butter, or a half cup of plain yogurt with a small handful of granola.)
Waking up with enough time to eat a small breakfast before intense workouts may be ideal, McDaniel adds. The extra calories in your system help prevent fatigue, so you have enough energy to complete your workout at a time of day when you might otherwise feel pretty exhausted. You’ll be able to push it harder when you have some fuel in you!
If you’re exercising later in the day and you’ve eaten a meal within the last two to three hours, you should be fine to do your workout without any additional source of pre-workout fuel, says McDaniel. But if you haven’t eaten recently, you should have a 100- to 200-calorie snack within 30 minutes to an hour before your workout so you’re mentally and physically prepared.
How long should you wait to exercise after eating? If you’ve just eaten a meal, you should wait two to three hours before you work out; and if you’ve just eaten a snack, wait about a half hour, McDaniel says.
If you’re going to do a cardio workout, this snack should be higher-carbohydrate, moderate in protein, and low-fat (but you don’t need to go fat-free). Specific examples include: a whole-wheat tortilla with a smear of peanut butter and a banana, half a turkey sandwich, or oatmeal with fruit and nuts.
If you’re going to do strength training, this snack should be higher in protein, moderate in carbohydrates, and low-fat. (4) Specific examples include: eggs and a slice of whole wheat toast, cottage cheese with fruit, or Greek yogurt with fruit and nuts.