Managing your weight is a vital part of protecting your health. Studies of 8,000 twins showed that being overweight doubled the risk of dementia, and being obese quadrupled that risk. In another study, obese people who lost weight following bariatric surgery had significantly improved memory and concentration after 12 weeks. (Small, Gary, MD. Author of The Memory Bible and The Alzheimer's Prevention Program. The Mind Health Report, Special Report, 1011-REV1111)