Stress affects people in a variety of ways. Some may lose weight, while others may gain. Both epinephrine and cortisol are adrenal stress hormones that might be partly responsible for these reactions. Cortisol increases your metabolism, but it also makes you hungry. So while your body may be burning more calories when you're stressed, you may eat more to compensate. If you're feeling stressed and it's affecting your weight, either up or down, be sure to talk to your doctor to help determine ways to manage it.
Stress and Your Metabolism
When you're under stress, whether physical or emotional, your body reacts by releasing a number of hormones. These hormones, which include epinephrine and cortisol, gear your body up to respond to the stress, often categorized as "fight or flight." Cortisol taps into your energy stores, including stored forms of glucose, protein and fat, to supply your body with the energy it needs to react. This process burns calories and increases your metabolism, which is your body's calorie-burning system.
However, cortisol is also considered a catabolic hormone, which means it breaks down muscle for energy. So while the stress may initially increase your body's calorie-burning furnace, the loss of muscle -- which is one way your body burns calories -- may ultimately cause an overall decrease in your metabolism. Muscle breakdown from one stressful incident may not have much of an effect on your metabolism, but long-term chronic stress might.
Stress and Your Appetite
While initially you may not have much of an appetite when you're stressed, if the stress persists you may become ravenous. Epinephrine helps keep your hunger at bay initially, but if stress continues, rising cortisol levels may increase your hunger. Cortisol not only speeds up your metabolism, it also stimulates your appetite -- and those hunger pangs may have you wanting foods high in fat and sugar. These unhealthy foods are comforting and seem to quell the area of your brain that processes stress and emotion, according to Harvard Health Publications, making you feel better. This may also be why you crave unhealthy treats during stressful times.
The Negatives of Stress: Weight Gain
While stress may temporarily increase your metabolism, it's not good for your weight. Chronic stress causes a dip in your metabolism from loss of precious calorie-burning muscle and increases your appetite and desire for unhealthy foods, and it may also cause an increase in body fat and belly size.
Additionally, cortisol also causes an increase in insulin resistance. This develops when your cells become unresponsive to insulin, which transports sugar from your blood into cells; this leads to an increase in blood levels of sugar and insulin. While the research is preliminary, there seems to be a connection between high levels of insulin and obesity, according to a 2012 laboratory study published in Cell Metabolism. Chronic stress that causes insulin resistance may also increase your risk of developing type 2 diabetes, according to a 2009 article from Today's Dietitian.
Exercise to Manage Stress and Increase Metabolism
To help manage your stress and improve your metabolism in a healthy way, consider adding exercise to your routine. While vigorous exercise seems to be the best way to combat stress, you might get some of the same health benefits by starting with a brisk 30-minute walk most days of the week. And with their meditation elements, yoga and tai chi not only help with stress but also build muscle to improve the number of calories you burn at rest. Be sure to talk to your doctor before starting any exercise program, to help you decide what regimen best suits your fitness needs.