According to a large study, increased carbohydrate consumption from sugary drinks, starchy vegetables and refined grains is associated with greater weight gain in midlife, while increased carbohydrate and fiber consumption from non-starchy vegetables, fruits and whole grains is associated with less weight gain.
Most of these associations were more pronounced in individuals with higher body weight, highlighting the importance of the source and quality of carbohydrates for long-term weight control.
The influence of carbohydrates on weight gain and obesity remains controversial, and little research has examined the association between changes in carbohydrate consumption over time and long-term changes in body weight.
To investigate this further, these associations were examined at 4-year intervals over a total follow-up period of 24 years.
The results are based on data from 136,432 women and men aged 65 or younger who participated in the Health Professionals Follow-Up Study and the Nurses’ Health Study 1 and 2.
At enrollment, all individuals were free of medical conditions such as chronic kidney disease, stomach problems, neurodegenerative diseases, respiratory diseases, cardiovascular diseases, cancer and diabetes.
Questionnaires on lifestyle, medical history, personal characteristics and other health-related factors were completed at the start of the study and every two to four years thereafter.
The results show that people gained an average of 1.5 kg every 4 years, which equates to an average of 8.8 kg over 24 years.
In women and men, increases in glycemic index and glycemic load, which measure the effects of different foods on blood sugar levels, were positively associated with weight gain.
For example, a 100 gram increase in added sugar or starch per day was associated with a 0.9 kg and 1.5 kg increase in weight gain over 4 years, while a 10 gram increase in fiber intake per day was associated with a 0.8 increase in weight gain kg was associated with lower weight gain over 4 years.
Increased carbohydrate consumption from fruits, whole grains, and non-starchy vegetables such as spinach, carrots, and broccoli was associated with less weight gain.
On the other hand, increased consumption of refined grains and starchy vegetables such as potatoes, corn and peas was associated with greater weight gain.
Further analysis found that replacing carbohydrates from sugar-sweetened beverages, starchy vegetables and refined grains with equivalent amounts of carbohydrates from non-starchy vegetables, fruits and whole grains was associated with less weight gain.
The associations were stronger in people who were overweight than in people who were normal weight. Most of these associations were also more pronounced in women.
Because this was an observational study, the cause could not be determined. There were also some limitations, including participants’ reporting of carbohydrate consumption estimates as well as weight results and possible errors in dietary measurement.
However, this was a large study that used recurring dietary assessments and validated questionnaires over a longer follow-up period, spanning the significant period of midlife weight gain.