​

Why does stress cause people to overeat?

​
📓 The short answer

Stress fuels overeating because it triggers the release of cortisol, a hormone that ramps up appetite and urges your body to stockpile energy for future threats, particularly with calorie-dense food.

📚 The long answer

Overeating is a very common response to feeling stressed. In fact, a 2012 survey found that 39% of us overeat or eat more junk food when feeling stressed out. Why does stress cause people to overeat? Let's break this down:

How does stress affect your appetite?

Stress is your body's reaction to potential threats, like a tiger or an all-caps email from your boss. Your "fight-or-flight" response gets your body ready to run from or fight the tiger/email by quickly redirecting its resources.

During acute stress, the hormone epinephrine (AKA adrenaline) triggers this fight-or-flight response, which suppresses your appetite. It's your body's way of telling you that you have more pressing things to deal with than finding your next meal.

If the threat goes away, your body will adjust back to its normal state and eating habits. But if you remain stressed for a longer period, the hormone cortisol is released. Unlike epinephrine, cortisol increases appetite. Your body is stockpiling energy to help you handle the next threat.

Your cortisol levels should return to normal baselines when the threat is finally over. But if the stress doesn't go away, your cortisol may remain elevated and cause you to overeat. Chronic stress can even lead to leptin resistance, making you feel hungry even when you've had enough to eat.

But when we're stressed, we don't reach for the carrot sticks. We crave something else...

Why do we crave junk food when stressed?

Humans (and many other animals) respond to stress by eating more foods high in sugar and fat. Why is that?

Reason #1: The body craves energy-dense foods.

In long-term stress, cortisol increases to help you gather up the energy to fight off the next threat. The most energy-dense foods happen to be foods high in sugar, fat, or both. You crave junk food during stress because it's to boost your calorie intake, which you'll need to fight off that tiger or email.

Reason #2: Junk food temporarily lowers stress.

Junk foods get called "comfort" foods for a reason: When you eat fatty, sugary foods, they do seem to calm your nervous system.

These foods have been found to temporarily reduce activity in your hypothalamic-pituitary-adrenal (HPA) axis responsible for regulating stress hormones.

Reason #3: Junk food activates the brain's reward system.

Junk food also activates the brain's dopamine pathways, which makes you feel pleasure and relief. This can create a feedback loop wherein we reach for the cookies when we're stressed because it makes us feel good.

Reason #4: Comfort food reduces feelings of loneliness.

Comfort foods — familiar, often sugary and fatty foods associated with safety and care — truly do seem to comfort us. One study found evidence to suggest that comfort foods can reduce feelings of loneliness, which can help us feel less stressed.

Reason #5: Stress weakens our impulse control.

We also eat more junk food simply because it's harder to resist tempting foods. Stress impairs activity in your prefrontal cortex, which normally helps with impulse control and decision-making. This makes it more likely we'll give in to eating junk food.

What factors make someone more likely to stress eat?

But not everyone overeats when they feel stressed out; some people even report eating less than usual. Your cortisol levels are strongly associated with how likely you are to "stress eat." So what factors into your cortisol levels?

• Adverse early life experiences: If you had exposure to stressful life events in your childhood (abuse, neglect, etc.), this can lead to lasting changes in your HPA axis which make you have higher baseline or reactive cortisol levels.
  ​
• Chronic sleep problems: Chronic short sleep and circadian misalignment (e.g. night shifts) are associated with higher evening cortisol and increased appetite for junk foods.
  ​
• Dieting: Restricting your daily caloric intake can put your body into a stress state, increasing the total daily cortisol levels.
  ​
• Being obese or overweight: If you have a high body fat percentage, you'll have higher levels visceral fat, the fat around your major organs. Visceral fat is biologically active and actually produces cortisol locally. On average, long-term cortisol levels are elevated in obese individuals.

• Being a woman: Women are more likely than men to turn to food as a way to cope with stress. Part of the reason for this is how female reproductive hormones play a role in the body's stress system.
  ​
  During the menstruation cycle, hormones estrogen and progesterone rise and fall. When estrogen is high (around ovulation), it lowers your appetite and can even dampen cortisol's effects. But progesterone does the opposite: When progesterone spikes (after ovulation), this hormone increases appetite and can make our stress response more reactive. This may explain why menstruating women often crave sweet foods about 7-10 days before their periods.

--- Thanks for reading this week's newsletter! If you have any thoughts, questions, or favorite GIFs, my inbox is always open. Just hit reply to send me a note! :) ​ All my best, Caitlin ​Click here to read five facts about Caitlin​

​

​Sources for this week's newsletter​

P.S. I typed the word "stress" 34 times over the course of this newsletter. I did consider mixing up my word choice, but I'm not going to stress over it.

🌐 Wikipedia article of the week

​Waffle House Index​

"The Waffle House Index is a metric named after the ubiquitous Southern US restaurant chain Waffle House known for its 24-hour, 365-day service. Since this restaurant always remains open (except in extreme circumstances), it has given rise to an informal but useful metric to determine the severity of a storm and the likely scale of assistance required for disaster recovery.

The metric was first conceived of by journalist Matt Dellinger and the term later coined by former administrator Craig Fugate of the Federal Emergency Management Agency (FEMA). The metric is unofficially used by FEMA to inform disaster response."

📚 Did you know all affiliate revenue from book purchases is donated to charity? Today You Should Know is an affiliate for Bookshop, an online book marketplace that supports local, independent bookstores. I frequently update the Today You Should Know recommended reading list with my favorite fiction and nonfiction books. And I donate all affiliate proceeds to Room to Read, a leading nonprofit for children's literacy and girls' education across Asia and Africa. It's a win-win-win: you get to read a book, small bookstores get some business, and money is donated to a great cause. ​ Find your next read

👀 Catch up on other curious questions

• ​Why do we look away in conversation when we're trying to think?​​
• ​Why is soccer not a popular spectator sport in the United States?​​
• ​What is a black hole?​​

P.S. 🤔 Do you have a question for the newsletter? Click here to submit your question (or reply to this email!)