Like most fitness questions, the answer to whether or not you should trade your morning oatmeal for an a.m. sweat session depends on your goals and your personal preference. The old adage, "The best workout is the one you're going to stick to," holds true here. If exercising on an empty stomach makes you nauseous, it's not a good choice for you.
But if your half-asleep alter-ego has no problem hitting the gym first thing in the morning, then it may be a great way to burn calories before your day kicks into high gear. Plus, while exercise is always a good complement to a healthy diet for weight loss, studies suggest that working out before breakfast may have a slight advantage when it comes to fat loss.
The Benefits of Fasted Exercise
When you exercise, usually your body burns glycogen (stored sugar) as fuel first. And when the body senses that glycogen has been used up, it revs up appetite to make up for lost glycogen, according to an April 2019 study from the Journal of Nutrition.
When you exercise on an empty stomach, however, the body burns fatty acids, meaning the increased appetite after your workout may not be as significant. Basically, fasted exercise is thought to burn fat for fuel and is associated with consuming fewer calories at later meals, which is a huge perk when you're trying to lose weight.
Your early morning workout may boast another perk. Fasted cardio's greatest benefit may be enhancing insulin sensitivity, which improves blood sugar levels to the healthy range, according to a small October 2019 study in the Journal of Clinical Endocrinology & Metabolism. It suggested that those struggling with prediabetes could benefit from working out before breakfast, as it helps the body clear sugar from the blood faster.
The Case for Eating Before a Workout
If you just can't work out on an empty stomach, that doesn't mean your fat-loss efforts are doomed. A November 2017 review in the Journal of Functional Morphology and Kinesiology found that despite increases in fat burning, exercising fasted did not result in greater fat loss than exercising after breakfast. Ultimately what matters is ending the day in a calorie deficit (burning more calories than you consume).
And if your goal isn't fat loss, but more aligned with performance goals, you should consider eating a meal before important or difficult training sessions. According to a 2016 position paper published in the Journal of the Academy of Nutrition and Dietetics, carbohydrates improve the intensity and duration of workouts while training fasted compromises the quality of the athlete's workout and training.
What to Eat Before and After Workouts
Of course, what you eat before and after a workout is just as important as when. Performance-oriented athletes with a goal of fat loss should aim for a minor daily calorie deficit and emphasize protein in their diet from foods like Greek yogurt, eggs, chicken, seitan, tempeh and fish to preserve muscle while burning body fat.
And those who prefer to eat before a workout probably know that a fatty meal of steak and eggs with hash browns makes for an uncomfortable workout session. Instead, choose a lighter, easier-to-digest meal that gives you enough energy to push harder and faster without feeling sluggish.
In order to ensure the meal feels comfortable in your belly during exercise, eat a meal or snack one to two hours before your workout and avoid high-fiber and high-fat foods such as beans, cruciferous vegetables or fried foods. Prioritize easy-to-digest carbs and pair it with a little bit of protein to help accelerate recovery.
Some great pre-workout snacks or meals include:
- Whole wheat toast with peanut butter
- A large banana and a hard-boiled egg
- Oatmeal with berries and nut butter
- Pretzels with hummus
- Dried edamame and dried fruit
- Sweet potato toast topped with nutritional yeast
Whether you're exercising with or without breakfast, the post-workout meal is non-negotiable. Choosing the right foods optimizes recovery and improves muscle mass creation. Aim for 15 to 25 grams of protein after exercise (4-6 ounces of meat, fish, Greek yogurt or 3/4 cup beans or tofu).
Pair with carbohydrates to refuel glycogen stores and rebuild muscles. Remember that while your body is readily able to burn carbs post-workout, choosing a carb source that's high in fiber keeps you fuller longer while feeding hungry muscles. Great high-fiber carbs include quinoa, beans and farro.
Some healthy post-workout options include:
- A protein shake blended with a large banana
- Rice and beans topped with nutritional yeast for some extra protein (or a palm sized portion of salmon)
- An omelette with a sweet potato
- A sandwich made with high-fiber bread and turkey or mashed chickpeas with sliced avocado
Bottom Line: Fed vs. Fasted Workouts
Creating an exercise regimen that's comfortable and realistic for you should be your top priority when figuring out when and how to work out. But there are a few things to keep in mind:
- Looking to build muscle and improve athletic performance? Eat a breakfast rich in complex carbohydrates prior to training.
- Working toward fat loss? Choose an eating and workout routine that's easy to stick to, whether it's training before or after eating.
- At risk of diabetes or looking to manage it? There's a chance that exercising fasted may help reduce the risk of diabetes and improve health by reducing blood sugar levels.
- American College of Sports Medicine: The Science of Exercise
- Mayo Clinic: Eating and Exercise: 5 Tips to Maximize Your Workouts
- American Heart Association: Food as Fuel Before, During and After Workouts
- Cambridge Core: Breakfast and Exercise Contingently Affect Postprandial Metabolism and Energy Balance in Physically Active Males
- Journal of Functional Morphology and Kinesiology: Effect of Overnight Fasted Exercise on Weight Loss and Body Composition
- U.S. Figure Skating Association: What Is Recovery Nutrition and Why Is It Important?