Do Hard Workouts Really Raise Your Cortisol? Experts Explain

You may have seen videos online warning that hard workouts raise a hormone called cortisol in a harmful way. Wellness influencers on social media blame cortisol for things like a puffy face, belly fat, and feeling burned out and tired. Some of them say people should skip intense exercise and do gentler activities like walking or yoga instead. But scientists say this advice misunderstands what cortisol actually does.

Cortisol is often called the "stress hormone." Your body releases it when you are in danger or under pressure, helping trigger what scientists call the "fight-or-flight" response. It sends more blood to your muscles and gives your body quick energy by turning carbohydrates into fuel. Cortisol also helps fight infection, controls blood pressure and heart rate, and helps you sleep at night.

Dr. Lena Fan is a hormone doctor at the Icahn School of Medicine at Mount Sinai. She says social media treats the word "cortisol" as if it simply means "stress," but that is not the full picture. True cortisol disorders are very rare — only about one percent of people have levels above the normal range. Even people with ongoing stress usually have cortisol levels that rise a little but stay in the healthy range.

When you exercise, your body releases cortisol as a healthy response to effort. The harder you push yourself, the more cortisol your body makes. Professor Anthony Hackney of the University of North Carolina says this is a good thing, because cortisol helps deliver more oxygen to your muscles. This allows your muscles to keep working during tough exercise.

After a workout, cortisol stays higher for a few hours, and then it drops — often lower than where it started before exercise. Over time, as your body gets used to hard exercise, your normal cortisol level can actually decrease. Professor Stuart Phillips of McMaster University says that even during very intense workouts, cortisol levels generally stay within the normal, healthy range. Dr. Fan compares it to building a muscle: your body becomes more resilient over time.

To get the most out of hard exercise, experts say you must eat enough food, especially carbohydrates, and rest properly between workouts. Dr. Marie Schaefer of the Cleveland Clinic explains that exercising hard without enough food can keep cortisol high for longer than usual. Doing too much exercise without enough recovery can cancel out its stress-lowering benefits. Sleep is also very important for keeping cortisol levels in a healthy range.

Gentler exercises like yoga, walking, Pilates, and tai chi are still great choices and can lower stress too. However, experts agree there is no reason to quit intense workouts just because of social media warnings about cortisol. Professor Phillips advises listening to your body and taking it easy on days when you do not feel your best. But giving up hard workouts out of fear of cortisol is not supported by science.