Dr Michael Mosley has revealed his number one food for staying in shape and boosting your brain, and it's a simple one.

He is one of Britain's most acclaimed and respected health gurus who first appeared on our screens in the 80s and has since gone on to influence people's health by encouraging them to switch up lifestyles.

Most notably, he is known for his weight loss plans and is the founder of the Fast 800 diet.

Speaking on his BBC Sounds podcast, Just One Thing, the health guru shared how eating one type of food can actually help reduce your waistline, despite it being very high in fats and calories.

The Just One Thing podcasts are short episodes - lasting 15 minutes each - where Dr Mosley shares just one thing (hence its name) that people can do to live a healthier life.

What is the one food that Dr Mosley believes reduces waistlines? Nuts.

What are the benefits of nuts?

Dr Mosley said: "It is mid-afternoon and I am craving some chocolate or perhaps a biscuit, but instead I am going for a protein-packed snack that can protect my heart, may stave off cancer, and give my brain a boost.

"I am cracking out the nuts."

He went on to describe how nuts often get "bad press" due to their high-fat content and in some cases, causing life-threatening allergies.

However, he explained: "But if, like me, you are able to eat nuts, this is definitely one thing you should start doing today."

He called nuts "nutritional power-houses" adding that when we eat them we get lots of fibre, and more importantly, polyphenols.

Wilts and Gloucestershire Standard: Series two of Just One Thing - with Michael Mosley (BBC)Series two of Just One Thing - with Michael Mosley (BBC) (Image: BBC)

This is what feeds our gut bacteria and reduces inflammation.

Nuts are packed full of "good things" like unsaturated fats, fibre and protein, as well as a number of compounds with anti-oxidant and anti-inflammatory properties.

There is even evidence that nuts are able to slow the ageing process at the cellular level.

Dr Mosley detailed how one massive study found that eating more nuts was associated with reduced weight gain over a five-year period.

It also showed a lower risk of becoming overweight or obese.

How they act as 'brain boosters'

The fact that nuts have such high levels of fat is also good for our brains, which need fat to work, some research shows that eating nuts can give your brain a boost.

On the benefits of nuts with your waistline, Dr Mosley spoke to Dr Sze-Yen Tan from Deakin University in Australia.

They detailed how there was no evidence that nuts could increase your bodyweight, despite having such a high amount of fat.

They added: "Those with higher nut intake tend to have lower body weight or lower body fat, so many studies have repeatedly shown that incorporating nuts into the diet doesn't make you gain weight.

"When we eat nuts we feel fuller and consequently adjust our diets in the next meal."

The expert recommended eating around 15-30 grams per day.

Mosley emphasised that nuts are a good replacement for sugary snacks like chocolates and biscuits, which often leave you craving more, as they have a high amount of protein which could help you feel fuller for longer.