DR MICHAEL MOSLEY: Want to beat your biscuit cravings? Fill up on bananas

Chocolate and biscuits are my downfall. And the annoying thing, as many will know, is that when you have a serious craving, it can be incredibly difficult to resist and extremely distracting.

For many people it’s chocolate, for others it’s crisps, pizza, biscuits or even something more exotic. Typically that food is sugary, salty and fatty, or combines all three.

Whatever it is, however much you’ve resolved not to give in to temptation, you find yourself going to the shops, having persuaded yourself you deserve a little treat. Next thing you know, you’ve scoffed the lot and wondering why you did it.

One big driver of cravings, for women at least, is hormones. As they won’t need me to tell them, at certain points in their menstrual cycles, many women may find themselves beset by intense cravings, particularly for carb-rich foods.

Now a new study has identified what triggers these cravings. Researchers at the U.S. National Institutes of Health asked 259 women, aged 18 to 44, to keep track of their cravings over the course of a couple of months. They also underwent blood tests.

More than half of them reported having cravings for sugary or salty foods, which were particularly intense in the week before their periods began.

What was more surprising was that the onset of these food cravings was linked to rising levels of chemicals in their blood that trigger inflammation in the body. The researchers are now exploring whether drugs that reduce inflammation will also reduce cravings.

It is not clear why a rise in inflammatory factors might trigger cravings, but it could be linked to the activity of microbes in our guts.

There is plenty of research showing that gut microbes play a key role in inflammation, with some producing chemicals that boost it, while others dampen it.

There is also mounting evidence that those clever microbes can also influence our behaviour by turning the food we eat into chemicals that travel through the blood to our brains and reward us for eating the sort of foods those particular microbes need to survive.

Dopamine, the ‘feel-good’ hormone, is produced in large quantities by gut microbes and it is not a huge stretch to imagine that the reason the microbes are producing it is to reward you for doing what they want you to do — such as eat more cake. And the more cake you eat, the more the sugar-loving microbes flourish and encourage you to eat more of it.

Similarly, gut microbes produce mood-controlling chemicals such as serotonin and GABA. Since cravings are often linked to feeling stressed or anxious, this is another way to make you eat more.

How strong is the evidence that all this is happening?

There is plenty of research showing that gut microbes play a key role in inflammation, with some producing chemicals that boost it, while others dampen it

A few years ago, researchers at Arizona State University conducted a review of the scientific literature to try to answer the question: ‘Is eating behaviour manipulated by the gastrointestinal microbiota [gut bacteria]?’

The answer was a resounding ‘yes’. They concluded that: ‘Microbes have the capacity to manipulate behaviour and mood through altering the neural signals in the vagus nerve [which runs from the gut to the brain], changing taste receptors, producing toxins to make us feel bad and releasing chemical rewards to make us feel good.’

So how can you use this knowledge to your advantage? The trick is to increase your intake of foods that allow the ‘good’ gut microbes — i.e. the ones that reduce inflammation and don’t encourage unhealthy cravings — to flourish.

I recently wrote about research looking at the impact of consuming more of a particular type of fibre, called inulin, on food cravings — the idea being that by doing so you are boosting the ‘good’ bacteria, such as bifidobacteria.

Dr Evelyn Medawar, a neuroscientist at the Max Planck institute in Germany, told me about a study she’d completed where overweight volunteers were given daily supplements containing 3g of inulin.

After two weeks the participants experienced major changes in the mix of microbes in their guts — and brain scans showed their food cravings were greatly reduced when they were shown images of fatty and sugary foods. 

You can buy inulin supplements and 3g a day is considered safe — but you may experience side-effects such as bloating, diarrhoea, constipation and cramps from such concentrated doses.

I personally prefer to get inulin from food: garlic, leeks, onions, asparagus, bananas and Jerusalem artichokes are good sources.

After chatting with Dr Medawar, I decided to give it a go and have spent the past couple of months ensuring that most days I’m having plenty of inulin-rich foods.

And it seems to be working; I now rarely crave chocolate or sugary biscuits and can quite happily say ‘no’ to dessert. Long may it last!

Garlic, leeks, onions, asparagus, bananas and Jerusalem artichokes are good sources of inulin

Doing more exercise may also help. In a study published last April, researchers at Washington State University in the U.S. trained a group of rats so that when they pressed a lever, they were rewarded with a tasty, high-fat pellet.

The rats were then divided into two groups: one group was put on a regimen of 30 days of treadmill running, while the others stuck to their regular activity levels.

After 30 days, both groups were put back in the cage with the levers and high-fat pellet dispenser. The rats that had done intense workouts were much less interested in pressing the lever, suggesting that exercising had reduced their craving for the fatty foods.

So next time you feel a craving, instead of going to the shops, try going for a run or brisk walk. Hopefully, by the time you get back, the cravings will have passed.