It may be a good sign to be overweight or obese in later life as weight loss is considered to be a strong indicator of impending Alzheimer’s disease

"Our research suggests that there are very early [bodily] changes associated with this disease," says researcher Jeffrey M. Burns, MD, who is the associate director of the University of Kansas Alzheimer’s Disease Center. "We think of Alzheimer’s as just a disease of the brain, but this may not be the case."
Brain imaging showed that 85% of people who are victims of mild mental impairment and who were of normal weight or underweight portrayed signs of beta-amyloid plaques, which is an important characteristic of Alzheimer’s disease.
Among those who portrayed mild impairment and were overweight, only 48% showed signs of the plaques.
Source-Medindia