Does Stress Cause Weight Gain? Doctors And Nutritionists Explain

Don't blame calories; blame cortisol.

by Emily Kelleher
Originally Published: 
A stressed man at work with his face in his hands.
Luis Alvarez/Getty

It might not be your sleep or exercise, calorie-in-calorie-out, saturated fats, or added sugars that have given you new love handles. It very well could be stress. Besides making you feel frazzled, stress sets off a chain of reactions within the body that affect blood sugar, hormones, and metabolism. It’s possible to gain weight due to the effects of stress alone, without making any lifestyle changes — and it’s unlikely you’ll be able to reverse the weight gain through diet and exercise alone, without addressing its source.

“Chronic stress levels can lead to increased cortisol levels,” says Dr. Michael Robinson, a naturopathic physician and certified nutrition specialist. This “makes it very difficult for the body to lose weight, and promotes belly fat.”

You can think of cortisol as a regulator for how many calories you burn. If all is well, cortisol lets your body burn around 2,000 calories a day (with a lot of factors such as body weight, muscle mass, and exercise affecting how many calories you burn). If you’re starving, however, cortisol levels rise and the body starts to burn the minimum it needs to keep itself alive. The body then loses its ability to break down fat for energy, forcing it to rely only on the energy supplied from food currently moving through.

This is a good thing if you’re truly starving. But if you’re stressed and have a normal intake of calories, and don’t change your exercise routine, cortisol can grind your metabolism to a halt. Then, your body starts storing fat.

To make things worse, cortisol is something of a double whammy. It triggers a spike in blood sugar while simultaneously disrupting the body’s ability to break down that sugar. It decreases the body’s sensitivity to insulin, the hormone that allows sugar to enter cells, says Dr. Sylvia Gonsahn-Bollie, a physician who specializes in obesity medicine. To top things off, stress is also associated with water retention, lower motivation, and sleep disruption.

So when you’re stressed, it’s incredibly easy to gain weight — and almost impossible to lose it. “No matter how much you try diet and exercising, your body’s not going to let the weight come off,” Robinson says. Even if high levels of stress initially lead to weight loss, as the body relies on adrenaline, when stress becomes chronic, it will eventually switch to cortisol.

So it’s not just stress-eating that’s tipping the scale. That said, it plays a part — and, again, cortisol is to blame. Cortisol throws off levels of ghrelin and leptin, the hormones which control appetite and satiety. This means that when you’re stressed, you might need more food to feel full and satisfied, says nutritionist Jessica Jaeger.

“Cortisol increases appetite, and if this is chronic, it will affect your microbiota and change your body into craving more sugar-rich food,” says Su-Nui Escobar, a registered dietitian and spokesperson for the Academy of Nutrition and Dietetics. Essentially, bacteria living in your digestive system, called microbiota, communicate with your brain, and visa versa. When you’re stressed, the type and number of bacteria in your gut can change, causing different cravings.

So, what can you do? First, focus on the stress, not the food. Avoid strict diets, and try not to fixate on the weight gain or beat yourself up for emotional eating. Punishing yourself will only increase stress and start the cycle all over again.

Instead, find an activity to manage stress that works for you. Meditation and mindfulness are big ones, and as crunchy as they sound, there’s tons of data that shows they’re powerful tools for reducing stress and anxiety and have real effects on the brain.

Journaling works too by forcing you to organize and explain your thoughts. Focus on unpacking the source of your stress and processing your feelings about it. Robinson suggests doing a brain dump at night, writing down everything you have to do the next day so it’s not hanging over you as you try to sleep.

You can also practice gratitude this way, by writing out all the things you’re thankful for, expressing thanks to others, or even just thanking them mentally. In one study, those who journaled about what they’re thankful for, as opposed to describing their day, experienced lower levels of depression. Those who went the extra step and expressed gratitude to others benefited even more.

Of course, exercise is essential. But do it for stress reduction, for the endorphins, and to spend time away from work and the kids and dishes. Right now, you don’t need to work towards a marathon or six-pack. Instead, use a workout as a time to get away from everything else in life. In a world filled with stressors, it’s the single best thing you can do.

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