Dementia study links obesity to up to 27% lower risk of death

Survival varied by weight

Compared with people in the normal-weight range, participants classified as overweight had a 16 percent lower risk of death. The reduction was 27 percent for class 1 obesity and 22 percent for class 2 and 3 obesity. Researchers accounted for smoking, existing medical conditions and demographic characteristics.

Long-term records offered context

The team used the Health and Retirement Study, which follows Americans aged 51 and older. Its analysis covered records from 1998 through 2022 and included 4,523 people who developed dementia after entering the study without the condition.

The long follow-up let researchers examine weight changes before diagnosis, body weight when dementia was identified and survival afterward. Earlier work by Zhang and Chang found that weight loss may begin as much as 10 years before diagnosis and intensify as the disease approaches.

Researchers urge caution

The authors considered whether bias might account for the apparent survival difference. Corresponding author Yuan Zhang said their analyses did not find that the major sources of bias they examined explained the association.

Study first author Virginia Chang said the research was not designed to test whether gaining weight improves survival. The researchers said weight status may offer a prognostic signal and that nutrition is important for people with dementia.

Extra weight is also associated with heart disease and diabetes, while overweight or obesity in middle age is linked to a greater likelihood of later dementia. The findings therefore describe an association after diagnosis, not a recommendation to gain weight.