Eating half a serving of nuts every day could stop you from gaining weight as you get older, research suggests.
Experts tracked almost 300,000 people for around two decades. They were asked about how many nuts they ate and how much they weighed. Results showed participants who ate half an ounce (14g) of nuts every day gained less weight and were less likely to become obese.
Scientists now say replacing unhealthy snacks, such as chocolate, with nuts could slow down the dreaded middle-age spread. The researchers say the study cannot establish cause and relied on self-reported data, which can prove to be inaccurate. But they suggest that chewing nuts takes more effort than eating fast food, while the high fibre content can make people feel full for longer.
Nut fibre also binds well to fat in the gut, meaning more calories are excreted, the researchers wrote in the published paper of their study. Nuts are rich in healthy unsaturated fats, vitamins, minerals and fibre, but are not often consumed for weight loss because they are calorie dense.
But there is evidence to suggest that quality of diet as well as counting calories plays a role in weight management.
Harvard University researchers analysed information on weight, diet and physical activity in three groups of people.
In terms of individual nuts, eating an extra half a serving of walnuts a day lowered the odds of becoming obese of the next four years by around 15 per cent.
No such associations were observed for increases in peanut butter intake, according to the researchers led by Dr Xiaoran Liu.
The findings remained true after taking account of changes in diet and lifestyle, such as exercise and alcohol intake.
Adults in the US pile on 1lb (0.45kg every year, on average. It is thought British adults gain a similar amount of weight.
Gaining 5.5-22lbs (2.5-10kg) in weight is linked to a significantly greater risk of heart disease/stroke and diabetes.
