BMJ: Cutting sugar and starch from the diet is associated with long term weight control

Sadly this is NOT a post about how eating these gorgeous looking cup cakes will make you slim!

Adapted from BMJ 30 Sept 2023

Association between changes in carbohydrate intake and long term weight changes. Wan Y et al.

This study looked at the association between changes of different types of carbohydrate and weight changes measured at four yearly intervals.

The data was retrieved from the Nurses Health Study, Nurses Health Study 2, and the Health Professionals Follow up Study. These studies were done between 1986 and 2015.

The participants at the start had to be in good health and aged 65 years or younger. They then completed follow up questionnaires every four years. They were asked about personal characteristics, medical history and lifestyle. Carbohydrate type and amount was calculated from validated food frequency questionnaires. The weight changes were self reported every two years.

Over 136 thousand health professional were questioned over the years.

On average participants gained 1.5 kg every four years amounting to 8.8kg on average over 24 years.

Foods higher in glycaemic index and glycaemic load tended to produce more weight gain. For example, a 100g a day increase in starch or sugar was associated with 1.5kg and 0.9kg greater weight gain over four years. A 10g a day increase in fibre however, tended to result in 0.8kg weight loss over four years. Other foods that increased weight were refined grains and starchy vegetables such as peas, corn and potatoes. The foods that tended to reduce weight were whole grains, fruit, and non starchy vegetables.

For example, over 4 years a 100g daily increase in non starchy vegetables a day equated to 2.6 kg extra weight. If non starchy vegetables increased by 100g a day the weight loss was 3kg.

The effects were more noticeable in women and in those who were already overweight or obese.

This study shows that not all carbohydrates have an equal effect on body composition. For long term weight management limiting added sugar, sugar sweetened beverages, refined grains and starchy vegetables would seem prudent. These can be helpfully replaced with whole grains, fruit and non starchy vegetables.