Middle-aged people should swap potatoes and bread for carrots and spinach to keep control of their weight as they get older, research suggests.
A team in the US acknowledged that the “role of carbohydrates in weight gain and obesity remains controversial”, but highlighted that few studies have linked changes in carbohydrate intake over time, and long-term changes in body weight.
They said an increased intake of carbohydrates from the likes of fizzy drinks, white bread and potatoes led to a higher rate of weight gain in middle age.
Swapping to whole grains, fruit and non-starchy vegetables could help better control body weight, they said.
To examine this, the team looked at body weight changes in a cohort of 136,432 people aged 65 at four-year intervals over 24 years.
The data was collected from patients enrolled on the Nurses’ Health Study, which took place from 1986 to 2010, the Nurses’ Health Study II from 1991 and 2015 and the Health Professionals Follow-Up Study from 1986 to 2014.
At the time of enrolment, those involved were free of cancer, diabetes, stomach problems, heart disease, breathing problems, neurodegenerative disorders or chronic kidney disease.
They completed questionnaires on lifestyle, medical history and other health-related factors every two to four years.
Researchers found participants gained an average of 1.5kg every four years, amounting to 8.8kg over 24 years.
However, a 100g a day increase in added starch was associated with a 1.5kg increase in weight gain over four years, with added sugar adding 0.9kg.
Participants who consumed 10g more fibre a day gained less weight (0.8kg), as did those who got their carbohydrates from whole grains (0.4kg), fruit (1.6kg) and non-starchy vegetables (3kg).
People who increased their intake of refined grains such as white bread gained 0.8kg more, along with those who had a higher intake of starchy vegetables such as corn and potatoes (2.6kg).
The associations were higher in females and in those in the study with excessive body weight.
The paper, published in the British Medical Journal (BMJ), said the findings “highlight the potential importance of carbohydrate quality and source for long-term weight management”.
It added: “Limiting added sugar, sugar sweetened beverages, refined grains, and starchy vegetables in favour of whole grains, fruit and non-starchy vegetables may support efforts to control weight.”
Researchers said the study was observational and had several limitations, including “reliance on self-reported estimates of both carbohydrate intakes and the weight outcomes, and potential errors in dietary measurement”.
Bridget Benelam, nutrition scientist at the British Nutrition Foundation, said: “This study adds to the evidence we already have that carbohydrate quality in the diet is important for health.
“While ‘carbs’ have had a bad press in relation to weight gain, we know that choosing wholegrain and higher fibre options, such as wholemeal bread, wholemeal pasta or potatoes with skins, has health benefits.
“Our healthy eating guidance already advises swapping more refined carbohydrate foods such white bread or pasta for whole grain versions and this study suggests that this may also have benefits for weight control.”
