Meet the experts: Amber Wheeler, MD, hey freya Medical Advisor and General Endocrinologist. Alexander Rothstein, CSCS, ACSM-EP, is an exercise physiologist and instructor for the exercise science program at New York Institute of Technology. Roxie Jones, CPT, is a strength and nutrition coach at Body Rox.

The Role Of Cortisol In Exercise—And Why It’s Not The Enemy

Cortisol is your body’s main stress hormone—it kicks in whenever you’re dealing with stress, including the physical stress of working out, says Rothstein. “The nickname ‘stress hormone’ creates a negative association with cortisol, but that couldn’t be further from the truth,” he says.

Often called the “fight or flight” hormone, it’s naturally released when you encounter a challenge—whether it’s a tough workout or a stressful workday—to help you power through. During exercise, cortisol helps fuel your muscles and manage physical stress by breaking down stored carbohydrates (a.k.a. glycogen) and fat, giving your body the energy it needs to perform.

Beyond fueling your workouts, cortisol supports recovery by managing inflammation and repairing muscle tissue, according to a study in Immunology and Allergy Clinics of North America. “Cortisol helps mobilize energy stores and repair muscle tissue after exercise,” says Rothstein. So, it’s a normal and necessary part of the process. Over time, regular exercise-induced cortisol spikes also help your body build resilience, making you stronger both physically and mentally. Exercise trains not just your muscles but your nervous and endocrine systems as well, teaching your body how to regulate cortisol appropriately, he says.

What cortisol does:

• Manages stress
• Regulates metabolism
• Controls inflammation
• Maintains blood sugar
• Supports blood pressure
• Facilitates natural circadian rhythm
• Repairs muscle tissue

Moderate-intensity exercise can significantly increase cortisol levels temporarily, which helps your body adapt and thrive over time, while low-intensity exercise tends to have minimal impact. Very high-intensity exercise causes dramatic spikes, according to a study in the Journal of Exercise and Nutrition. In the study, moderate-intensity exercise led to significant cortisol increases, while high-intensity exercise caused dramatic spikes—up to 80 percent higher than baseline. Meanwhile, low-intensity exercise didn’t raise cortisol levels much at all and sometimes even reduced them. Interestingly, aerobic workouts, especially long and intense ones, tend to spike cortisol more than resistance training, according to the study.

Aside from the type of workout you’re doing, other things that can affect how much cortisol your body pumps out include age, gender, and fitness level, says Rothstein. Plus, as we get older, our bodies respond differently to exercise, and men and women can experience those cortisol changes in unique ways.

Beyond its role in stress, cortisol fluctuations are an important part of regulating blood sugar, metabolism, and inflammation, and cortisol supports recovery after physical exertion, according to Stat Pearls. It’s also part of your body’s natural daily rhythm, peaking in the morning to help you wake up and gradually tapering off throughout the day.

Now, how hard and how long you exercise makes a big difference in how cortisol affects your body and your muscle health. A little rise in cortisol during exercise is beneficial, but too much—such as from prolonged or overly intense workouts—can tip the scale, leading to muscle breakdown. “Cortisol is not inherently bad,” Rothstein says. “The key is allowing your body enough recovery time to balance the catabolic (breakdown) and anabolic (build-up) phases of exercise.”

When to test cortisol levels: For most average people without specific symptoms such as chronic fatigue or unexplained weight changes, cortisol testing usually isn’t necessary. Cortisol naturally fluctuates throughout the day, and a single blood test may not tell you much. Testing is more beneficial when there’s a clinical suspicion of a medical condition or if symptoms significantly impact daily life.

This is particularly a concern for those already at risk of muscle loss, such as older adults or individuals with certain health conditions. However, most people aren’t exercising at a consistent enough intensity or duration to worry about cortisol causing negative effects, according to a meta-analysis in Trends in Sports Sciences that examined more than 40 existing studies regarding the role of cortisol in exercise. For moderate exercisers, the study showed these temporary spikes are a positive signal for your body to adapt and grow. Without these cortisol responses, your progress could stall.

Why Cortisol Gets A Bad Rap When It Comes To Bloating And Inflammation

One of the biggest myths circulating online is the idea that exercise-induced spikes in cortisol cause “cortisol face” or “moon face”—a puffy, swollen appearance assumed to be caused by elevated cortisol levels. While chronic stress and persistently high cortisol can contribute to fluid retention and inflammation over time, short-term increases in cortisol as a response to exercise don’t have the same effect, according to the same Trends in Sports Sciences review referenced earlier. “Cortisol face is not a common occurrence in healthy individuals unless there’s an underlying hormone disorder or medication like corticosteroids involved,” says Rothstein.

Short-term increases from exercise, as seen in studies of low- and moderate-intensity workouts, are unlikely to cause visible puffiness, especially when balanced with good recovery habits. The causes behind puffiness or bloating are often varied and multifactorial, but it’s likely caused by other factors such as dehydration, poor sleep, or a high-sodium diet—not necessarily your workout routine, says Rothstein. Prioritizing good recovery and overall wellness habits, like staying hydrated, getting enough rest, and eating plenty of protein and fiber helps keep cortisol levels in check and minimizes these effects.

So, next time you hear about “cortisol face” or other myths, remember: Stress, when managed well, makes you stronger.

Signs You Might Be Overdoing It

While moderate exercise-induced cortisol can help you crush your workouts and reach your fitness goals, too much of a good thing can lead to problems. Chronic overtraining—though uncommon for most exercisers—can cause consistently elevated cortisol levels, which might result in symptoms like:

• Fatigue or feeling run down
• Trouble sleeping or staying asleep
• Frequent colds or illnesses
• Difficulty recovering between workouts

For those wondering if cortisol causes weight gain, the answer is nuanced. Persistent high cortisol levels can lead to increased appetite or fat storage, but exercise-induced spikes are short-lived and unlikely to have this effect, according to research. “Cortisol becomes problematic when it’s persistently elevated due to overtraining or insufficient recovery,” says Dr. Wheeler. “Signs include fatigue that doesn’t improve with rest, decreased performance, trouble sleeping, irritability, and frequent illness.” If you’re experiencing symptoms of overtraining or exercise begins to feel draining rather than energizing, listen to your body and reassess intensity or incorporate more rest days into your routine.

“I help clients experiencing high cortisol avoid overtraining by scheduling two to three days of moderate intensity strength training while promoting parasympathetic-forward activities outside of the gym such as walking, breath work, and meditation,” says Roxie Jones, CPT, a strength and nutrition coach. “Training intensity can always be adjusted to help manage stress better.”

Tips To Keep Cortisol In A Healthy Range

Your biggest takeaway: Cortisol is only problematic when it’s chronically elevated—and balance is the key to managing it, says Rothstein. Focusing on healthy habits—like stress reduction techniques, consistent exercise, a balanced diet, and adequate sleep—often brings cortisol into balance naturally. Here are some simple strategies experts recommend to keep this hormone working for you, not against you:

• Practice mindfulness. Activities like yoga, meditation, or even deep breathing can reduce overall stress and lower cortisol levels, say Rothstein and Jones.
• Prioritize recovery. Schedule regular rest days and use tools like foam rolling or stretching to help your body recover, says Rothstein.
• Balance workout intensity. Integrating two to three low- to moderate-intensity sessions per week is an excellent way to manage overall cortisol levels while staying on track with your fitness goals, says Jones.
• Fuel thoughtfully. Eating a protein-rich snack after exercise helps regulate blood sugar and mitigate cortisol’s effects, says Rothstein. (Think: Greek yogurt with berries or a protein shake.)
• Do your best to maintain a healthy, consistent sleep routine. Aim for seven to nine hours of quality sleep each night. Poor sleep can disrupt cortisol’s natural rhythm, says Jones.