Reuters reports a study published in The Lancet Diabetes and Endocrinology which suggests that being too thin increases the likelihood of developing dementia. After observing almost two million people in the UK, researchers found that the most underweight individuals carried the highest risk (34 percent) for developing dementia in old age, and the risk dropped steadily as BMI went up. These findings contradict many previous studies which linked obesity to dementia risk, but those studies were much smaller than this one. The study had some limitations such as the fact that dementia is known to contribute to weight loss even up to a decade before diagnosis, which may have skewed the results. The best way to reduce dementia risk is by leading an overall healthy lifestyle with regular exercise, proper eating habits and no smoking.