Ahandful of nuts a day could cut the risk of obesity by almost a quarter, research by Harvard University suggests.
Experts said that eating a few nuts each day, instead of turning to crisps or biscuits, could help to ward off middle-aged spread.
The research also examined the potential impact of swapping an unhealthy snack – such as chocolates, pies and donuts – for nuts.
Over the course of the study, those taking part were putting on average of 0.7 lbs a year.
The twenty year study of 290,000 adults aged 24 to 75 found a higher intake of nuts was associated with a 23 per cent lower risk of putting on 11 pounds, and of becoming obese.
Nuts are rich in healthy unsaturated fats, vitamins, minerals and fibre, but they are calorie dense, so it has often been debated about whether they can help dieters.
The findings, published in the online journal BMJ Nutrition, Prevention & Health, come from an observational study, so could not prove cause and effect.
They also highlighted evidence that the high unsaturated fat content of nuts increases resting energy expenditure, which may also help to stave off weight gain. In addition, the effort of chewing nuts could reduce the desire to continue snacking, researchers suggested.
But researchers suggested that the high fibre content of nuts can delay stomach emptying so making a person feel sated and full for longer. Nut fibre also binds well to fats in the gut, meaning that more calories are excreted.
They said turning to a handful of nuts a day was “a relatively manageable way of helping to curb the onset of obesity”.
The US study involved almost 290,000 men and women, aged between 24 and 75.