Muscle Evolved

Is It Bad to Work Out On An Empty Stomach?

By Zac Hyde · · Updated

Contents

You probably know about the importance of supplying your body with protein to increase your muscle mass.

So, what about eating before working out?

In this article, we will see whether it is safe to work out on an empty stomach. We will also cover the essential macronutrients to include in your pre-workout meal.

What happens when you work out on an empty stomach?

For most healthy people, working out on an empty stomach is safe, but it can affect how you perform. After a long fast, such as overnight, your stored carbohydrate (glycogen) is lower, so you may feel tired or less energetic during hard or long workouts.

Your body also burns a larger share of fat for fuel during fasted exercise. That does not automatically mean more fat loss over time, because your total calorie balance matters most.

A review of 46 studies found that eating beforehand improved performance in longer aerobic exercise, but made little difference in shorter sessions.

If you have diabetes or tend to get lightheaded, talk to your doctor before exercising without eating.

If you had your last meal 2–4 hours ago, your body should have enough energy to use without having to break down any valuable structures.

When should you eat?

Depending on the type of activity you are performing, you may or may not need to eat.

For instance, walking, gentle yoga, and golfing are low-intensity activities that probably do not require any fuel.

If you are doing hard strength training, eating beforehand can help you perform your best. Long-duration exercise, such as marathon training, depends heavily on carbohydrate for fuel.

A good rule of thumb is to eat a full meal about 2–3 hours before working out, or a small, easy-to-digest snack closer to your session. This gives your body fuel without making you feel heavy.

What to include in your pre-workout meal

Protein-rich foods

Protein consists of amino acids, which are vital to grow your muscles and optimize performance.

During strength training, your muscle fibers develop microscopic damage that requires repairing. Fortunately, your body is smart; so, instead of repairing the damaged tissues and calling it a day, it will promote the growth of those fibers with the help of hormones.

If you train regularly, the International Society of Sports Nutrition recommends 1.4 to 2.0 grams of protein per kilogram of body weight per day. For instance, if you weigh 70 kg, that is roughly 100 to 140 grams of protein per day.

In a previous article, we covered when to drink protein shakes, before or after working out.

Carbohydrates

Your muscles use glucose to generate energy during exercise.

Therefore, it helps to include some carbs in the meal you eat 2–3 hours before exercise. If you eat closer to your workout, simple, low-fiber carbs such as a banana are easier on the stomach.

Green is key!

Vegetables are extremely healthy as they contain large amounts of vitamins, minerals, and antioxidants.

These nutrients support your overall health and recovery. Just keep large portions of high-fiber veggies out of the hour right before training, since they can upset your stomach.

Takeaway message

Working out on an empty stomach is generally fine for light or short workouts. For long or intense sessions, eating beforehand usually helps you train harder.

If you have any questions or concerns, please don’t hesitate to share your thoughts in the comment section below.

Sources

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