It is well known that stress can lead to weight gain, with many of us reaching for a chocolate bar or a glass of wine after a hard day.
But it is not just comfort eating that makes us pile on the pounds – our bodies naturally build up fat when we are under pressure, say researchers.
They have found that stress triggers a hormone called Adamts1 which generates fat cells in the body. This can not only create an unsightly spare tyre around the waist but also wraps fat around internal organs like the liver and pancreas, raising people’s risk of type 2 diabetes and heart disease.
Fresh evidence that stress can make you fat comes from Stanford University School of Medicine, California in the US. Senior author of the study, Dr Brian Feldman, assistant professor of paediatrics, said stress hormones encourage fat cells to mature.
He added: ‘We think it is a signal that there may be hard times ahead, a trigger to store as much available energy as you can.’
It was once believed that fat cells were just passive bags of calories, but recent research shows they send and receive important hormonal signals. Stored within ‘fat depots’ in the body, they can influence stem cells around them – cells which can turn into any type of tissue in the body.
Scientists at Stanford say the trigger for this, the Adamts1 hormone, turns stem cells into more cells ready to store fat.
It means, perhaps unfairly, that once you are already fat, your body is likely to create more fat cells. Stress, the scientists say, triggers a similar effect.
The team conducted a series of experiments using fat cells in a dish, followed by studies on mice and humans.
Dr Feldman said: ‘You’re ingesting food, and some signal has to tell your body to make more fat. We didn’t know what was triggering that process in vivo (in the body). This new research goes a long way to fill in the in-between steps.’
The findings come after research last year which showed that a job which becomes more demanding can make you put on weight.
That study found workplace stress leads to poor diet and comfort eating. Researchers at University College London said people in this situation were 20 per cent more likely to become dangerously overweight.
The new findings from Stanford, published in the journal Science Signalling, showed that Adamts1 is the major signal causing stem cells to begin storing fat.
In the main this affects visceral fat, which is particularly dangerous for health as it builds up around vital organs including the heart.
Dr Feldman said fighting the effects of the hormone was far from simple: ‘If you block fat formation, extra calories have to go somewhere in the body, and sending them somewhere else outside fat cells could be more detrimental to metabolism.
‘We know from other researchers’ work that liver and muscle are both bad places to store fat, for example. We do think there are going to be opportunities for new treatments based on our discoveries, but not by simply blocking fat formation alone.’
The study looked at glucocorticoids, a group of steroid hormones produced under stress, and how they trigger Adamts1. They come from the adrenal glands above the kidneys, in response to a signal from the brain.
The same hormones are believed to trigger comfort eating, as they act directly on taste cells on the tongue, affecting how they respond to sugary foods.
Glucocorticoids, released naturally in the body or in steroid medications, had the same effect in creating fat cells out of stem cells as overeating.
Dr Feldman said: ‘We’ve basically seen that the glucocorticoid signal is embedded in the high-fat feeding pathway. Connecting those dots together was really exciting.’