Why Do People Lose Weight When Stressed?

You are equipped with a natural stress response, which can affect how much or how little you eat. Your stressors may be acute, like having a near-accident, or chronic, such as going through a lengthy divorce process. When you’re under stress, your body releases hormones that activate your “fight or flight” response so you can deal with the stressor and return to stasis as quickly as possible. One of these stress hormones inhibits appetite, while the other boosts it. Whether you lose or gain weight under stress may depend on your eating habits when you aren’t stressed out. A calorie counter is a good resource to help ensure you're getting the best quality nutrition each day.

Stress Hormones at Work

When you experience a stressful event, the first hormone to kick in is a corticotrophin-releasing hormone, or CRH. Within seconds, a rush of CRH into your bloodstream shuts down your appetite. So if your car swerves on an icy road or your child falls off a jungle gym, the last thing you want to do is eat.

As the stressor subsides, however, your body releases glucocorticoids, particularly the hormone known as cortisol. This makes your digestion start up again so you can replenish the fuel you lost when you were trying to control the car or racing to your child’s aid. It takes much longer for cortisol to leave your bloodstream than CRH, reports Robert M. Sapolsky, Ph.D., in his book “Why Zebras Don’t Get Ulcers.” If the stress incident ends after 10 minutes, Sapolsky says, you’ll have that amount of time when CRH is in your bloodstream, while it might be two hours before cortisol clears your system. So you experience a relatively short time in which your appetite is dulled, and a long stretch in which your body is primed for feasting.

Stress and Weight Loss or Gain

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More people under stress tend to be hyperphagic, or overeaters, and fewer are hypophagic, or undereaters, according to Sapolsky; he says the ratio is 2 to 1. One study of university students in Great Britain found an even greater ratio: 55 percent of participants gained weight during their stressful first year of school, compared to only 12 percent who lost weight. Female students in the study were more susceptible to both weight loss and gain than their male counterparts. The results appeared in the journal Physiology & Behavior in 2007.

The prevalence of hyperphagia under stress makes sense, given the longer period in which cortisol remains in your system making you want to eat. In addition, chronic stress keeps your cortisol levels perpetually high, for example, if you are struggling to adapt to a new situation, like college, or you are caring for a sick or elderly relative.

Eating Patterns and Weight Loss

If you tend to gain weight under stress, you're probably a “restrained” eater under normal circumstances, according to a study published in Physiology & Behavior in 2006. That means you tend to diet, and when you’re under stress, you choose foods that are off-limits while dieting, like high-fat and high-sugar treats. In contrast, “unrestrained” eaters are less likely to be dieters, and they tend to eat less food when they're under stress.

The loss of appetite by an unrestrained eater may result in weight loss over the course of a stressful experience. If you take in less food than your body needs to perform its many functions, you will lose weight over time. For example, if your body requires 1,700 calories a day, but you eat only 1,200 calories daily for a month while you’re in the midst of a stressful situation, you will lose more than four pounds.

Recovering From Weight Loss

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If your appetite tends to flag when you’re stressed, try eating small meals and snacks throughout the day to keep your calorie count stable. Go for nutrient- and calorie-dense foods – those packed with nutrients that are higher in calories per serving. Stay away from empty-calorie junk foods that could further deplete your system of needed nutrients.

Good choices for maintaining your calorie count or regaining weight include lean protein, nuts and seeds, avocado, dairy, dried fruit, fresh fruits like bananas and mangoes, olives and olive oil. Have some celery sticks with hummus, a container of Greek yogurt, an ounce of nuts and raisins, a piece of whole-wheat toast with almond butter, two hard-boiled eggs, or a milk and banana smoothie if that’s all you can manage to eat. Getting enough protein foods each day helps replace muscle you may have lost when you were under stress.