We’ve covered before how stress can cause sugar cravings and make it harder to resist them once you’ve got one. Stress depletes willpower, and it typically also causes a negative mood, which is one of the biggest triggers of cravings around. Unfortunately, sugar is actually a very effective stress reliever in the short term.
But that’s not the only way that stress can sabotage your efforts to improve your health. Even if you have the world’s most iron willpower and you’ve never given in to a craving in your life, stress is still having a serious and measurable negative effect on your health, and probably also on your weight – did you know that everyday stressors can actually slow down your metabolism by a significant amount?
Here’s how it works…
Stress Controls the Biology of Weight
Stress doesn’t just regulate eating behavior in the form of comfort-eating and cravings. It also controls hormonal and metabolic processes that can cause weight gain.
Let’s start with a mouse model. One group of researchers has come up with a way to inflict chronic bullying on mice, which (understandably) makes them very stressed. It’s basically the mouse equivalent of having a really awful boss, overbearing coworker, or horrible relationship with someone you can’t escape.
In these mice, the chronic social stress doesn’t just make the mice fat (although it does that too). It makes them fat and very, very sick. It gives them hormonal disorders including dysregulated cortisol rhythms, depression-like symptoms, social withdrawal, and changes to their immune and endocrine systems, as well as spontaneously inducing symptoms that look a lot like binge-eating disorder. The mice subjected to chronic stress gain weight and develop symptoms very similar to Type 2 Diabetes and metabolic syndrome.
If that sounds exactly like all the hormonal, metabolic, and immune/autoimmune problems that go along with obesity in humans, then you’re on the right track. Obesity isn’t just about accumulation of fat cells; it’s about inflammatory, hormonal, and metabolic changes that throw off your body’s natural regulation of how many fat cells you ought to have. This model doesn’t just show stress-induced weight gain where “weight gain” means your skinny jeans are a little tight; it shows stress-induced obesity.
When the bullied mice in this group are allowed to eat as much as they want, they overeat (and often binge eat) and gain a lot of weight. So you might think that they’re just becoming obese because they’re bullied, so they eat junk. But hold that thought, because the unstressed mice don’t gain weight even if they’re given the same obesogenic diet: they show a bunch of different metabolic compensation mechanisms that prevent weight gain (like extracting fewer calories from their food and higher body temperatures).
Stress somehow impairs the ability of the stressed mice to make metabolic adaptations to a higher-calorie intake. Stress makes the difference between getting fat and not getting fat, on the same obesity-inducing diet!
And lest you think this only works in mice…
- In this study, couples who showed more stress and hostile behavior over a marital disagreement while eating dinner had significantly lower (average of 128 calories) post-meal energy expenditure.
- In this study, women with a just one stressor on the previous day burned 104 fewer calories after a meal than women who reported no stressors.
- One of the biggest predictive factors for obesity in the US is poverty, and if you want a source of chronic, crushing stress, you can’t get much more horrible than poverty.
- Stress hormones cause insulin resistance and impair the function of beta cells in the pancreas, both of which contribute to developing Type 2 Diabetes.
- The hormonal response to stress, in the form of a chronically activated fight-or-flight response, impairs glucose tolerance, decreases levels of testosterone and thyroid hormones, and increases insulin resistance and inflammation.
So stressed humans show the same kind of adaptations as stressed mice: even if they don’t actually comfort-eat to deal with stress, their metabolisms slow down, their energy expenditure decreases, their hormones get all off-kilter, and their blood sugar regulation goes down the drain. Stress, in other words, is a metabolism-destroying machine.
This is just another proof of how silly the “eat less, move more” theory of weight loss is: if you take up walking on the treadmill, and dutifully walk off 100 calories, but it makes you miserable to do it and becomes a source of stress, then you literally might as well not have done it at all. It’s also a point in favor of forgetting all about the “metabolism-boosting tips” you might have read about in the checkout line: in terms of metabolic bang for your buck, managing stress will get you a whole lot further than eating blueberries or drinking cold water.
Stress and Evolution
Of course, this response to stress is all part of your evolutionary heritage – until very recently, “stress” meant “not enough food.” In that environment, conserving energy during periods of stress makes absolutely perfect sense: if there really is a famine, burning fewer calories and being more motivated to seek out high-calorie food could potentially save your life.
People who get fat and sick working stressful jobs are evolutionary successes: their survival programming is working exactly as planned. Unfortunately, our survival drives haven’t quite caught up to the fact that “stress” no longer means “not enough food:” these are responses that just aren’t adaptive in the modern environment.
So How do I Prevent It?
If you want to spend your life trying to fight these survival pressures – well, it’s your life. But it’s a lot easier not to engage that “famine alert! Must preserve energy!” drive in the first place by managing your stress well, so you aren’t chronically experiencing the biological and psychological stress response.
You don’t have to avoid every situation that could plausibly be “stressful:” that’s impossible anyway. But you don’t have to let yourself get anxious over things that you can’t control (traffic, uncooperative weather, turbulence in an airplane…).
- Proactively using stress management techniques can help you avoid the crazy cortisol/adrenaline stress-hormone rush even in a situation you might find stressful.
- Small, planned doses of hormetic stress may actually be helpful because they make you more resilient to other stressors.
- Making time to get enough sleep, gentle movement, and rest in your day helps a lot for overall stress management.
Summing it Up
Stress is notorious for causing comfort-food cravings and depleting the willpower you need to make healthy choices, but it can do a whole lot of metabolic damage even if you never cave to the sugar demons. Stress wreaks metabolic havoc by reducing the total number of calories that you burn in a day, impairing blood sugar control, and affecting insulin, testosterone, and thyroid hormones.
So if you really want a metabolic leg up, don’t go chasing the next metabolism-boosting superfood. Instead, go for the less-sexy option that actually works: regular sleep, moderate exercise (that you enjoy!), and proactive stress management.