What Happens to My Body if I Exercise Too Soon After Eating?

Your nutritional and dietary habits influence the effectiveness of your exercise program. What and when you eat are the biggest factors. Eating too soon before your exercise program can be counterproductive to your goals and leave you feeling sick. In addition, if you don't eat properly before exercising, your body does not have a larger reserve of glucose, making it turn to your fat stores sooner.

A salad, measuring tape, and clock on a rustic table. Credit: karandaev/iStock/Getty Images

Exercising on a Full Stomach

When you exercise, the muscles producing your movements call on your heart for extra blood. At rest, 15 to 20 percent of your circulating blood feeds your skeletal muscles, but during exercise this increases to 80 percent. To facilitate this change, your body constricts and dilates your blood vessels. The vessels to the unnecessary systems for exercise such as digestion, urination and reproduction are constricted, limiting the amount of blood to these organs. If you eat right before exercise, your digestive organs and your skeletal muscles fight for blood flow, making exercise more difficult to perform.

Fat Burn

Eating right before exercise can also inhibit your body's ability to use fat for energy during activity. Exercising with minimal food inside your stomach makes for the perfect combination of hormones inside your body. Your body releases adrenaline and suppresses insulin. Insulin is a hormone that prompts your body to store nutrients. Without insulin circulating in your blood, your muscles are readily available to break down and use fatty acids.

Other Negative Side Effects

Exercising on a full stomach can make you feel just plain sick. Eating a large amount of food before exercising can cause stomach pain and cramps. It may even lead to nausea and diarrhea, according to the National Obesity Foundation.


Time your meals according to when you are going to exercise. If you eat a large meal, wait at least three hours before exercising. A small meal should be followed by a wait period of two to three hours. Exercise can be followed within an hour of a small snack.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.
Load Comments

Copyright © 2019 Leaf Group Ltd. Use of this web site constitutes acceptance of the LIVESTRONG.COM Terms of Use , Privacy Policy and Copyright Policy . The material appearing on LIVESTRONG.COM is for educational use only. It should not be used as a substitute for professional medical advice, diagnosis or treatment. LIVESTRONG is a registered trademark of the LIVESTRONG Foundation. The LIVESTRONG Foundation and LIVESTRONG.COM do not endorse any of the products or services that are advertised on the web site. Moreover, we do not select every advertiser or advertisement that appears on the web site-many of the advertisements are served by third party advertising companies.