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.
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 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.
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.
Over more than 20 years of monitoring, participants were asked every 4 years to state their weight, and how often, over the preceding year they had eaten a full serving (28 g or 1 oz) of nuts.
The findings held true after taking account of changes in diet and lifestyle, such as exercise and alcohol intake. Two of the authors were partly funded by The Peanut Institution and the California Walnut Commission, but the funders were not involved in the study design.