Should You Work Out on an Empty Stomach? Experts Weigh In

The Pros and Cons of Exercising While Fasting

Working out on an empty stomach, also known as fasted training, has become an increasingly popular fitness trend. Proponents claim that exercising in a fasted state can boost fat burning and improve endurance. However, others argue that working out without fueling up first may diminish performance.

The truth likely lies somewhere in the middle. As with most things related to health and fitness, whether or not to workout fasted depends on the individual and their goals.

Potential Benefits of Exercising Fasted

May burn more fat – Exercising in a fasted state forces your body to rely on fat stores for energy rather than carbohydrates from food.
Increases metabolism – Fasted training may give your metabolism a small boost since your body has to work harder to produce energy without recently consumed calories.
Aids fat loss – Over time, training fasted may result in slightly greater fat loss compared to exercising after eating.

Downsides to Look Out For

Decreased performance – Without readily-available energy from food, you may fatigue earlier during fasted workouts.
Increased muscle breakdown – Fasted training can result in higher levels of muscle protein breakdown as your body scrambles to find fuel sources.
Hunger and irritability – Exercising on an empty stomach can lead to lightheadedness, nausea, and low blood sugar for some people.

Tips for Exercising Fasted Safely and Effectively

If you want to give fasted training a try, here are some tips to help you stay healthy, safe and get the most out of your workouts:

Listen to your body – Pay attention to signals like fatigue, lightheadedness and nausea which may indicate fasting is not right for your body.
Stay hydrated – Drink plenty of fluids before, during and after your fasted workouts to avoid dehydration.
Include BCAAs – Consuming branched chain amino acids prior to exercise can help reduce muscle breakdown during fasted training.
Keep workouts moderate – High-intensity fasted training is more likely to have adverse effects. Stick to moderate cardio or lighter weights.
Break your fast soon after – Be sure to eat a mix of protein and carbohydrates within one hour post-workout to promote recovery.

Should You Give Fasted Cardio a Try?

Research on fasted exercise is still emerging and results seem mixed. Some studies show minor benefits for fat burning while others find no differences compared to exercising after eating.

Most experts agree that fasted training done occasionally likely won’t harm healthy individuals. But frequent high-intensity fasted workouts, especially combined with chronic calorie restriction, could have detrimental effects.

As with adopting any new fitness regimen, it’s wise to proceed cautiously and pay close attention to any negative impacts like ongoing fatigue, muscle soreness, illness or changes in mood.

In the end, whether or not to workout fasted comes down to personal preference and lifestyle. Listen to your body, fuel smart, and find what works best for you.

FAQ

Is it OK to workout fasted every day?

No, working out fasted every day is not recommended. Frequent fasted exercise, especially high-intensity workouts, can put excessive strain on the body and lead to issues like fatigue, decreased performance, and muscle breakdown. Limit fasted training to a couple times per week at most.

How long should you fast before a workout?

Most research on fasted exercise looks at fasting for 12-18 hours overnight. Anything longer than that is not necessary and could potentially be detrimental to workout performance and recovery.

Is fasted cardio better first thing in the morning?

For most people, working out first thing in the morning makes the most sense when doing fasted cardio. This allows you to exercise after fasting overnight while your body is in a natural fasted state. Exercising late at night after a full day of fasting is not recommended.

Should you take BCAAs before fasted cardio?

Yes, taking 5-10 grams of branched chain amino acids (BCAAs) before fasted exercise can help reduce muscle protein breakdown and thus promote muscle retention and growth. Leucine, isoleucine and valine are examples of BCAAs.

What should you eat after fasted cardio?

After completing fasted cardio, it’s important to eat a balanced meal within the first hour. Consuming 20-40g of protein along with carbohydrates and healthy fats will help replenish glycogen stores, stimulate muscle protein synthesis and recovery from your workout.