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Stress and weight gain

Tamara Willner
Written by

Tamara Willner

Medically reviewed by

Fiona Moncrieff

6 min read
Last updated April 2024

When it comes to weight loss, stress isn’t usually an area that we focus our attention on. However, it’s an essential piece of the puzzle and can have a big impact on our food choices and waistlines.

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The impact of stress of food choices

One research study investigated how our eating patterns change when faced with a stressful situation. They assigned participants into two groups: a stressed group and a non-stressed group.

The stressed group was asked to prepare a 4-minute speech, expecting it to be filmed and assessed after a lunchtime meal. The non-stressed group listened to a passage of neutral text before eating their lunch. The meal included a variety of sweet, salty, bland, high-fat, and low-fat foods.

The researchers found there was no difference in the amount of food eaten between the stressed and non-stressed groups. However, they did observe that emotional eaters ate sweeter, high-fat foods and a more energy-dense meal overall compared to the unstressed group and non-emotional eaters.

This suggests that those prone to emotional eating are most likely to eat and snack more on unhealthy comfort foods if placed in a stressful situation.

Key point:

  • Feeling stressed can lead to choosing sweeter, more energy-dense, high-fat foods.

Hormones and stress eating

Other scientific studies have observed that people who have higher levels of the stress hormone cortisol are more likely to snack throughout the day and eat more food overall compared to those with lower levels of cortisol.

One particular study looked at the changes in cortisol levels and food intake in a cohort of university students. They found that in the lead-up to the final term exams (the ‘stressor’), participants showed increased cortisol secretion, reduced dietary restraint (i.e. reduced willpower), and increased caloric intake. These changes were strongly linked with an increased BMI.

There’s also a scientific explanation as to why comfort foods tend to be carbohydrate-dense, such as pastries, cakes, chocolate, and crisps. We know that stress increases the release of cortisol. To bring this cortisol back down to normal levels, we need another hormone called serotonin. Carbohydrate consumption increases serotonin release, while protein lacks this effect.

This is why many people learn to overeat carbohydrates to soothe negative emotions and reduce stress. However, this can lead to insulin resistance and weight gain.

Key points:

  • The stress hormone, cortisol, can reduce willpower and increase energy intake.
  • We crave carbohydrates when we’re stressed because they increase serotonin, the hormone that brings cortisol back down.

Stress and the brain

There’s also another piece to this puzzle. New research has found that it might not be calories alone which lead to stress-associated weight gain.

A recent study split mice into two groups: a stress group and a non-stress group. Both groups were then further divided into a healthy diet or an unhealthy diet.

The stressed mice that ate the healthy diet showed no difference in body weight compared to the unstressed mice. However, the stressed mice that ate the unhealthy diet gained more weight than the non-stressed mice who ate the same unhealthy diet. This suggests that the type of diet we eat when stressed plays a significant role in weight gain.

Infographic showing that stress can impact weight gain from an unhealthy diet.

To better understand this, the researchers looked into the brains of the mice.

They found that a molecule called neuropeptide Y (NPY) was produced in the brain in response to stress. NPY has been shown to stimulate food intake. Interestingly, it’s release is controlled by insulin.

Chronic stress resulted in slightly raised insulin levels in the mice with healthy diets. But those mice who were chronically stressed and had a bad diet showed insulin levels that were ten times higher than non-stressed mice who ate a healthy diet.

These higher insulin levels were then triggering more NPY to be released, which further stimulated appetite and lead to increased food intake. As a result, these mice gained more weight and developed further insulin resistance.

This suggests that our insulin levels will be much higher if we’re eating an unhealthy diet when stressed, as opposed to a healthy diet. These raised insulin levels will trigger more NPY to be released, which means we’re hungrier, we eat more, and we gain more weight.

Key points:

  • Eating an unhealthy diet when stressed may cause more weight gain than eating the same unhealthy diet when you’re not stressed.
  • The brain produces a molecule (NPY) that stimulates food intake when we’re stressed, causing us to overeat.

Stress and sleep

Stress can make it harder to sleep, and sleep is important for weight loss as well as overall health. As a result, sleep deprivation can increase your desire and cravings for food, which leads to weight gain. You’re also less likely to participate in physical activity if you’re sleep deprived.

How to prevent weight gain from stress

The most impactful and sustainable way to prevent weight gain from stress is to control the stress in the first place. Different stress relieving techniques will work for different people. Here are 5 top tips to reduce stress-related weight gain:

1) Try meditation

A study demonstrated that a 3-day crash course in meditation reduced the activity in the brain region that processes stress (the amygdala). On top of this, meditation can help us to move past negative stress or anxiety triggers, which may be causing us to overeat. If you are new to meditation, try to practice 2 minutes of deep breathing each day. You can include it in your daily routine, for example, when you are waiting at the bus stop.

2) Change the way you think about stress

Can stress be useful? Studies suggest that if you view stress as a positive thing, that pushes you to achieve your goals, rather than a negative barrier it changes your bodies’ response to stress.

3) Adjust your bedtime routine

This is one of the easiest practical things you can do to ensure a good night’s sleep and reduce your stress levels the following day. Limiting screen time, writing a to-do list for the next day, and supplementing vitamin D are just some of the things you can do to sleep better.

4) Practise mindful eating

When you’re stressed you might eat mindlessly and not even realise the quantity you’re consuming. Practising mindful eating can reduce this. Concentrate entirely on your food, and even if you feel your mind wandering, carry on. You will likely find that you need to eat less, as you become more in tune with your body’s hunger signals and are much more aware of what you’re eating.

It also matters where you eat. When surrounded by distractions such as the TV or your mobile phone, or even sitting at your desk at work, we’re not often present in the moment. Being distracted from eating can lead to eating more than our body’s need. Ideally, eat at a table with a chair and actively minimise other distractions. Eating in the company of others is a great way to spend mealtimes.

5) Gentle exercise

Gentle exercise, like walking or yoga, can have a huge, positive impact on your mental health. If you start to feel overwhelmed or distressed, pause and take a 10-minute walk around the block.

Alternatively, joining a yoga class can be an enjoyable social experience and help you to learn breathing techniques that will reduce stress. If classes aren’t for you, there are many free online yoga videos that you can follow in the comfort of your own home.

Take home message

  • Stress can impact our eating patterns and waistlines in a number of ways, particularly if you’re an emotional eater.
  • When faced with a stressful situation, we often have less willpower and are more likely to choose carbohydrate-dense foods.
  • When chronically stressed, the type of diet we eat could have a big impact on our insulin levels, appetite, and overall food intake.
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