Life has been pretty stressful over the last year or so, and many of us have developed ways to cope with it. One common ‘helper’ people turn to when stressed is food, particularly unhealthy ‘comfort’ foods.

This, alongside the reduction in activity many have experienced, means that one study found that half of people report gaining weight during the lockdown.[i] But why are we driven to eat more when we are stressed?

When we eat something delicious, our brains release chemicals that make us feel good. If we eat a donut when we are stressed, we feel better, for a little while at least. The problem is that many of us are stressed a lot, particularly at the moment. Our brains are very good at learning to repeat behaviours that have helped us in the past, so if that donut helped last time, it will encourage you to eat another the next time you are stressed. Rather than an occasional pick-me-up, comfort eating becomes a habit- and habits are hard to break. This is particularly true if the initial learning opportunity happened during childhood, when our brains are at their most flexible and changeable.

But what does it mean in terms of the brain to say we have developed a habit? That first time, we ate a donut because we were driven by a desire for a reward. Dopamine signalling in the nucleus accumbens made that food our goal, and we ate it. We experienced its deliciousness, and it made us feel better, so that behaviour (eating a donut) was reinforced. The brain has learnt it is a good thing to do when we are stressed. Over time though, as we repeat the behaviour, a different part of our brain takes over. The dorsal striatum becomes involved, and we now reach for that donut on autopilot, without actively wanting or enjoying it… Eating when stressed has become a habit.

But in the long term this self-medicating with tasty treats just might cause knock on problems beyond the expanding waistline. Some argue that overeaters experience withdrawal symptoms when avoiding their favourite foods. Certainly, anyone who has been on a diet will have experienced how grumpy it can make you! The theory goes that denying yourself something delicious makes you anxious, and activates your stress system. You have learnt that food helps you cope with this state, so, of course, you are driven to eat to relieve the negative emotions. In fact, because of this system you may even end up eating more compulsively than if you hadn’t tried to avoid the food in the first place.

And while it may make you feel better in the short term, some studies in animals found that consuming delicious food regularly, boosting your happy chemicals every time, actually desensitises the reward system in the long term. People with obesity do seem to fit this pattern, showing a reduction in dopamine receptors in reward areas of the brain, and a smaller response in this brain region when eating tasty food. This could lead to overeating, as an individual needs more and more food to produce the same sensation of satisfaction. And it may make you more prone to negative emotions in the long term, causing a vicious cycle.

So what can we do? One important finding is that classifying foods as ‘bad’ and cutting them out of our diets entirely isn’t the answer- in fact, it can backfire. When we deny ourselves tasty food, we can end up obsessing over it. If I tell you not to think of a pink elephant, chances are you will think of one. Similarly, denying yourself that chocolate cake may lead you to think about it more, and eventually give in, eating more than you would have if you had eaten it immediately, and feeling stressed and guilty about it[ii]. And over the long term, some studies suggest people who diet are more likely to gain weight[iii][1].

So instead of diets, there is a new approach on the block. Known as ‘health at every size’, this puts the focus on increasing healthy behaviours, rather than losing weight. It also aims to reduce the stigma around weight, which, it seems, might be part of the problem when it comes to the health of people in larger bodies. Evidence is emerging that, when compared to weight loss interventions, this approach is more successful at improving the health of individuals over the long term. So add more fruit and vegetables to your diet, rather than restricting sweets. Think about what you can do to boost your health, rather than focusing on the number on the scales. And cut yourself some slack- we are all going through a difficult time, and if you come out the other side a few pounds heavier, it’s really not the end of the world.

Ginny’s new book all about brain chemicals is called Overloaded and it’s out now. Get it here and support independent bookshops in the UK or here on Amazon worldwide.

[1] Although this is an association, so it could equally be that people more prone to putting on weight are more likely to diet.

[i] getting-used-to-life-under-lockdown.pdf (kcl.ac.uk)

[ii] Resisting temptation: Effects of exposure to a forbidden food on eating behaviour – ScienceDirect

[iii] How dieting makes the lean fatter: from a perspective of body composition autoregulation through adipostats and proteinstats awaiting discovery – PubMed (nih.gov)

Medicare’s search for effective obesity treatments: diets are not the answer – PubMed (nih.gov)

Ginny Smith is a science presenter and writer. A Natural Sciences and Psychology graduate of Cambridge, Ginny performs science shows all over the world and presents a wide range of science content for the likes of the Cosmic Shambles Network and the Naked Scientists. She is the co-author of three DK Publishing books looking at science, food and the human body. Her frist solo book, Overloaded is out in April 2021. She is @GinnySmithSci on Twitter.

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