Should you work out on an empty stomach? That depends.

It’s often recommended that you work out first thing in the morning before eating breakfast, in what’s known as a fasted state. This is believed to help with weight loss. However, working out after eating may give you more energy and improve your performance.

Read on to learn the benefits and risks of working out on an empty stomach, plus suggestions for what to eat before and after exercise.

Exercising on an empty stomach is what’s known as fasted cardio. The theory is that your body feeds on stored fat and carbohydrates for energy instead of food you’ve recently eaten, leading to higher levels of fat loss.

Research from 2016 points to the benefits of working out in a fasted state in terms of weight management. The study among 12 men found that those who didn’t eat breakfast before exercising burned more fat and reduced their caloric intake over 24 hours.

Some research dispels this theory. A 2014 study on 20 women found no significant differences in body composition changes between groups who ate or fasted before working out. As part of the study, researchers measured body weight, percent body fat, and waist circumference over four weeks. At the end of the study, both groups were shown to have lost body weight and fat mass.

More in-depth research over a longer period of time is needed to expand upon these findings.

Working out on an empty stomach could also lead your body to use protein as fuel. This leaves your body with less protein, which is needed to build and repair muscles after exercise. Plus, using fat as energy doesn’t necessarily mean that you’re going to lower your overall body fat percentage or burn more calories.

While there’s some research to support working out on an empty stomach, it doesn’t necessarily mean that it’s ideal. When you exercise on an empty stomach, you may burn valuable energy sources and have less stamina. Low blood sugar levels may also leave you feeling lightheaded, nauseous, or shaky.

Another possibility is that your body will adjust to continually using fat reserves for energy, and start to store more fat than usual.

Follow a balanced diet to enhance your athletic performance.

  • Eat whole, nutritious, natural foods.
  • Include healthy carbs such as fresh fruits and vegetables, whole grains, and legumes.
  • Choose healthy fats, such as olive and coconut oil, ghee, and avocados.
  • Get protein from lean meats, eggs, and low-fat dairy products.
  • Nuts, seeds, and sprouts are healthy additions to your diet as are foods rich in iron such as fish, cooked beans, and green vegetables.

If you decide to eat before working out, choose an easily digestible meal containing carbohydrates, proteins, and fats. Eat about 2 to 3 hours before your workout. If you’re pressed for time, snack on an energy bar, peanut butter sandwich, or fresh or dried fruit.

Stay hydrated before, during, and after exercise by drinking water, sports drinks, or juice. Smoothies and meal replacement drinks can help you increase your fluid intake, too.

Certain foods can improve and speed up your recovery after training. Eat foods containing carbs, protein, and fiber within 30 minutes to 2 hours of finishing your workout. Healthy proteins can boost your immune system and speed up wound healing. Foods that contain vitamins C and D, zinc, and calcium are also beneficial.

Here are a few healthy post-workout options:

  • low-fat chocolate milk
  • fruit smoothie
  • energy bar
  • sandwich
  • pizza
  • whole-grain bread
  • soy milk
  • nuts and seeds
  • prunes or prune juice
  • yogurt with berries

The type of activity you’re doing can help determine whether you should eat before your workout. For light or low-impact exercises, such as walking, golfing, or gentle yoga, you may not need to fuel up beforehand.

However, you should always eat before exercise that requires a lot of strength, energy, and endurance. This includes tennis, running, and swimming. It’s especially important if you plan to work out for longer than an hour.

There are certain times you may want to eat during strenuous exercise lasting more than an hour, such as during a marathon. This is necessary to maintain blood glucose levels needed to continue moving. It also helps you avoid using up stored energy in your muscles, which can help you build muscle mass.

Check in with your doctor if you have any health condition that’s affected by what you eat and how you exercise.

If you have diabetes, carefully monitor your blood sugar levels before, during, and after exercising. If you have a thyroid condition, low blood pressure, or hypertension, be sure you’re eating around your exercise program whenever it’s appropriate for managing your condition.

If you do work out on an empty stomach at times, don’t sweat it, but it may not be best for strenuous or long-lasting activities. You are your own best guide, so listen to your body and do what feels best for you. Stay properly hydrated, maintain a balanced diet, and live a lifestyle in line with your best health interests. And remember to talk to your doctor before starting any new exercise program.