How Long After Eating Can You Work Out? Waiting Time, Health Risks and Nutrition

Equipping your body with enough fuel and the right types of food to sustain you through an exercise routine is important. But when you eat can be just as crucial as what you consume.

To avoid figuring out when to eat, some people may think it's safer to exercise on an empty stomach or that it's perhaps even better to do so, with the logic being it forces you to burn stored body fat to supply the energy for your workout in the absence of food.

However, eating before exercise will enhance your performance level, compared with working out in a "fasted state," according to a Colorado State University nutrition article.

Any meals before a workout "should be sufficient but not excessive" to prevent both hunger and undigested food during exercise, the university explains.

But when exactly is the optimal time to fuel up before working out?

How Long Should I Wait to Work Out After Eating?

The short answer? There is no definitive time frame. It depends on the food you eat and the amount consumed.

Plus, every individual's body works differently, so with time you'll have a better gauge on how long before exercising is best for you to eat and how much food is the right amount for your body.

Speaking to Newsweek, Dr. Tricia Psota, a registered dietitian nutritionist and member of the American Society for Nutrition (ASN), said: "There are no set recommendations regarding how long to wait to exercise after eating. Most people can exercise about 30 to 45 minutes after snacking and about two to three hours after a meal to avoid side effects."

A woman having a bowl of cereal.
A woman having a bowl of cereal with fruit. How long you should wait to exercise after you've eaten will depend on what you've eaten and how much you've consumed. iStock/Getty Images Plus

Roxana Ehsani (RoxanaEhsani.com), a registered dietitian nutritionist and spokesperson for the Academy of Nutrition and Dietetics, told Newsweek how long you should wait to exercise "depends on what a person eats."

For example, if a person eats "high carb, low fiber, low fat and low protein food" such as a piece of fruit, pretzels, saltines or applesauce (all of which are easy to digest), it can be consumed just before a workout, as these "can be easily quickly digested by your body and used immediately as fuel quickly for exercise," Ehsani said.

However if you've just eaten a well-balanced meal consisting of vegetables, high quality protein, a high fiber grain and healthy fats, it likely will take about 2.5 hours to three hours to fully digest.

Typically, carbohydrates get digested the quickest, followed by protein, while fats take the longest, she explained.

Foods containing lactose (such as dairy products) also take longer to digest than others.

So gym-goers should "wait until that meal has been almost digested before beginning a workout or else a person might feel uncomfortable when trying to workout with a full stomach," Ehsani advised.

For competitive athletes, Colorado State University says a "pre-game meal" of around 500 to 1,000 calories consumed three to four hours before an event allows for "optimal digestion and energy supply."

The meal should be high in starch in the form of complex carbohydrates (such as breads, cold cereal, pasta, fruits and vegetables).

Complex carbohydrates are digested "at a rate that provides consistent energy to the body and are emptied from the stomach in two to three hours," the university explains.

A table spread of vegetable dishes.
A table spread of vegetable dishes. If you've had a well-balanced meal before a workout, you should wait until the food has been almost digested before beginning your exercise routine. iStock/Getty Images Plus

Health Risks for Eating Too Soon Before a Workout

The ASN's Psota said there are "no known major health risks" associated with working out too soon after you've eaten. But some may experience sluggishness, as well as cramping or other forms of gastrointestinal (GI) discomfort.

Ehsani said: "A person may experience GI distress, such as an upset stomach, nausea, cramping, reflux, bloating, diarrhea if they workout too soon after eating. But there are no serious health risks for working out too soon after eating."

Competitive athletes should not eat any carbohydrates one and a half to two hours before an event. "This may lead to premature exhaustion of glycogen stores in endurance events," Colorado State University says.

Caffeine consumption should also be carefully considered before a workout, as it may lead to dehydration due to increased urine production. Stick to eating familiar foods before exercising, as then you know your body can tolerate these foods.

Athletes will also want to have smaller meals if there is less time remaining before an event.

"If a competition is less than two hours away, athletes may benefit from consuming a liquid pre-game meal to avoid gastrointestinal distress. A liquid meal will move out of the stomach by the time a meet or match begins. Remember to include water with this meal," the university advises.

Waiting Too Long to Work Out After You've Eaten

Let's say you have your pre-workout food at 8 a.m. (with the intention of working out by 9 a.m.) but get held back and don't start your workout until 10 or 11 a.m. Will the pre-work snack I had earlier still energize my workout?

Ehsani explained the disadvantage of working out a while after you've eaten is that you may feel hungry and may have limited or no energy to workout as long as you were hoping for.

"There may be very limited energy supply left. So have another pre-workout snack and try to workout within about 30 to 45 minutes of having your pre-workout snack," she advised.

The exact time it takes for the food to hit your bloodstream varies depending on the amount you consume, according to the registered dietitian nutritionist.

But typically, one to two servings of any good pre-workout foods (like a banana, graham crackers, pretzels, applesauce, crackers), which are all quickly digested, will take about 45 minutes to an hour to reach your bloodstream and provide you with energy for a workout, she said.

A man having protein shake.
A man having a protein shake near a table spread of fruit and milk at a gym. iStock/Getty Images Plus

When Should I Eat After Working Out?

You'll need to eat carbohydrates after a rigorous workout to rebuild the energy stores in your muscles.

Those who exercise for over 90 minutes, should eat or drink more carbohydrates (such as a sports bar, trail mix with nuts, yogurt and granola), possibly with protein, two hours after working out. For those who exercised for less than an hour, water is usually all that is needed after a workout.

The Academy of Nutrition and Dietetics recommends: "For strenuous workouts, carbohydrates should be consumed within 30 minutes of finishing the workout. This can be done with a sports drink or a carbohydrate-rich snack such as a fruit smoothie."

A bowl of vegetables, chicken breast, rice.
A bowl of vegetables and chicken breast served over rice. A meal containing both carbohydrates and protein should be eaten within two hours of working out for muscle recovery. iStock/Getty Images Plus

Post-Workout Nutrition: Chocolate Milk and Other Foods to Eat

The ASN's Psota said a meal or snack containing both carbohydrates and protein should be eaten within two hours of working out, if possible, to aid muscle recovery and replace glycogen (a complex sugar) stores used during exercise.

Additionally, it's important to rehydrate and replace any fluids and electrolytes (minerals in your blood and other body fluids) that were lost during exercise.

"If a substantial amount of time occurs between working out and eating, one may miss out on optimizing muscle repair and nutrient replenishment," Psota explained.

Ehsani also said: "A mix of carbohydrates and protein are excellent to have post-workout. They work to refuel your depleted glycogen stores and repair muscle tissue that may have been broken down during exercise."

Some of the post-workout snacks recommended by Ehsani include:

  • A fruit smoothie made with greek yogurt, protein powder or cottage cheese (to get the protein).
  • Low-fat chocolate milk (popular for athletes). The Academy of Nutrition and Dietetics explains: "Because of its favorable carbohydrate and protein content, chocolate milk is indeed an effective recovery aid." But water and water-rich foods such as fruit are also great post-exercise food options, the academy says.
  • A parfait (a frozen dessert) made with low fat Greek yogurt and fruit.
  • A wholegrain bagel or toast with peanut butter or almond butter and a piece of fruit.
A bowl of vegetables, chicken breast, rice.
A bowl of vegetables and chicken breast served over rice. A meal containing both carbohydrates and protein should be eaten within two hours of working out for muscle recovery. iStock/Getty Images Plus