Stop stress from making you overeat
By: Maria Cross
Tags: Weight Loss, Food, Depression, Mental Health, Stress

Stress is bad for your mental health. It’s not great for your heart or immune health, either. Furthermore — and just to rub salt into your wounds — it can also make you fat. But the consequences of stress are not inevitable: once you understand what’s going on, you can fight back.

Stress can also be good for your mental health and overall survival. The stress response is designed to save your life, when called upon to do so. It also stimulates imagination and creativity. Likewise, eating is both essential and a pleasure. Issues arise when normal stress crosses a line, and so too does normal eating.

At the heart of the turmoil created by mental anguish and overeating is the brain’s reward system and the hormones that interact with it, in particular ghrelin.

Ghrelin is the hunger hormone, produced mainly in the stomach. When all is working well, it tells your brain when you are hungry. Thus, starvation is avoided. But with prolonged, unrelenting stress the normal ghrelin response is disrupted and you fail to differentiate between genuine hunger and a craving for something to stop the stress.

The reward system directs us away from pain and towards pleasure. We’d all rather stay and have another drink than go home and face the music. Pleasure takes the form of not only food but also addictive substances, including drugs and alcohol.

Several areas of the brain form part of the reward system, and they are activated by the neurotransmitter dopamine.

There are two major dopamine pathways involved in the reward system, the most important being the mesolimbic dopamine pathway. This connects a region of the brain called the ventral tegmental area (VTA) with a region called the nucleus accumbens (NAcc), found in the ventral striatum.

The VTA is the main source of dopamine, produced in anticipation or expectation of a reward. This dopamine ‘projects’ to the nucleus accumbens, the reward centre. When this happens, you experience a surge in the feeling of pleasure.

Dopamine also projects to the hypothalamus, the hippocampus, the amygdala, and the prefrontal cortex. These regions are concerned with memory of a particular reward, the emotional associations you make with that reward and the choices you subsequently make. Therefore, the effect that dopamine has in these regions is to remind you of how much you like something, how good it makes you feel and why you should have it again.

We form a memory of something pleasurable and produce dopamine when that something becomes available again. When it comes to addictive substances, more and more dopamine is produced, meaning ever more amounts are required to get the same high.

Food is a source of reward and pleasure, and this is where ghrelin comes into the equation. Circulating ghrelin levels are elevated following stress. This excessive ghrelin is able to override any feeling of fullness you may have by directly targeting the VTA and nucleus accumbens, and increasing levels of dopamine, “to increase food motivation”.

“Ghrelin has recently emerged as one of the major contributing factors to reward-driven feeding that can override the state of satiation”

Ghrelin promotes food intake, even when satiety has been achieved. You are unaware that you are full and go seeking a reward. Not surprisingly, overweight people have been observed to eat more when stressed, in the absence of hunger.

The reward you seek doesn’t take the form of anything too healthy, obviously. No — what you want is what is euphemistically termed “palatable” foods, and which you may know as comfort foods. These are foods that combine fat with sugar.

Palatable, processed and guaranteed to provide

Now, there’s nothing at all wrong with fat — readers of this publication will be aware of just how vital the right kind of fat is to the human body, in particular the brain. Fat on its own does not provide reward; you’re unlikely to crave a lump of butter when you’re going through hell. But think about something that combines fat with sugar — think chocolate — and your reward centres light up like a Christmas tree. The list of palatable foods is a long one: cake, cookies and all things sweet, plus crisps, chips and every form of refined carbohydrate snack (which are essentially sugars), combined with vegetable oil to provide the fat component.

Just about every form of processed junk food available to you is designed by manufacturers to feature this winning combo, guaranteed to provide the dopamine you crave, and then some. They know precisely what they are doing.

“..the power of the reward system over feeding behaviour should not be underestimated.”

Palatable foods offset normal appetite control. Injection of ghrelin into the VTA of rodents has been shown to increase the intake of palatable food. Rats, like humans, have a predilection for anything that combines fat and sugar to create a powerful reward. The association between stimulus and reward is quickly established.