A study shows that swapping starchy carbohydrates for whole grains, fruits and vegetables significantly reduces weight gain in midlife.
US researchers found that ditching foods like potatoes and white bread for healthy foods like berries and brown bread helped reduce the risk of weight gain.
Consuming 100g of non-starchy vegetables daily, such as broccoli, carrots and spinach, reduced weight gain by 3kg every four years.
For comparison: consuming 100g more starchy products such as bread, rice and pasta increased their weight by 1.5kg over the same period.
Dr. Yi Wan from Harvard University said: “The results highlight the potential importance of carbohydrate quality and source for long-term weight control, particularly in people with excess body weight.”
“Limiting added sugars, sugar-sweetened beverages, refined grains and starchy vegetables in favor of whole grains, fruits and vegetables can support weight control efforts.”
Weight gain in midlife is common as hormonal changes reduce muscle mass and metabolism slows.
This is particularly the case in women, as fat often accumulates on the stomach, hips and thighs during menopause.
Previous research has shown that carrying a spare tire is more dangerous than general obesity.
Around 38 percent of adults in England are overweight and a further 26 percent are obese.
The NHS says obesity costs £6.1 billion a year, but the total cost of all associated conditions is likely to be much higher.
The latest study, published in the BMJ, looked at how your diet affects your risk of weight gain in middle age.
They tracked more than 136,000 men and women for 24 years, measuring their weight and asking about their diet every four years.
On average, people gain 1.5 kg at each check-up, for a total of 8.8 kg.
By consuming 100 mg of added sugar per day, they gained 0.9 kg more weight every four years.
Just 10 mg more fiber per day resulted in them gaining 0.8 kg less over the same period.