The Connection Between Body Fat And Dementia Is Not What You Think

The surprising results of a study on weight and dementia risk are not at surprising as they first seem, according to our experts. (Photo: Getty Images) 

If you eat well and exercise regularly, you’ll live a longer, healthier life — that’s a connection we’re all familiar with. But a surprising new study is calling that link into question.

Researchers from Britain’s Oxon Epidemiology and the London School of Hygiene and Tropical Medicine analyzed medical records of nearly two million people with the average age of 55 for two decades, and found that the more body fat people had, the less likely they were to develop dementia. Those who were overweight were 18 percent less likely to develop dementia, and people who were classified as obese had a 24 percent reduction.

By comparison, underweight people had a 39 percent greater risk of developing dementia compared to those who were a healthy weight.

According to the Alzheimer’s Association, one in three seniors dies with a form of dementia and Alzeheimer’s disease is the only top 10 cause of death in America that can’t be prevented, cured, or slowed. The Mayo Clinic and other leading medical organizations list physical activity as a possible way to reduce the risk of developing dementia, which makes the new study findings even more shocking.

Lead study researcher Nawab Qizilbash, MD, told the BBC that his team was thrown by the study’s conclusions and acknowledged that the findings are “controversial.”

Related: Can You Prevent Dementia Through Nutrition?

But Harvard University professor Deborah Blacker, MD, a geriatric psychiatrist who conducts research on Alzheimer’s disease, tells Yahoo Health that the findings are “not as surprising as they seem.”

She explains the probable connection between obesity and a reduced risk of developing dementia this way: “Getting to late life is less likely when you’re overweight. If you do get to late life if you’re overweight, it’s more likely that other things are in your favor.”

According to the National Institutes of Health, being overweight or obese increases a person’s risk of developing type 2 diabetes, heart disease, high blood pressure, stroke, and some forms of cancer, among other illnesses. But while obesity will lower the odds that someone will live longer, Blacker says weight becomes more complicated in late life due to survival.

Related: Researches Analyze Ronald Reagan’s Speech For Early Signs Of Alzheimer’s 

However, being underweight in late life can be a signal that something is wrong with a person’s health. Weight loss is also directly linked to dementia, which may explain why underweight people in the study were more likely to develop the disease. (Some sufferers can lose their sense of smell and appetite in the very early stages of the disease, and consequently may become underweight.)

While the study results were surprising, Blacker says people shouldn’t use the new findings as an excuse to stop working out or eating well. “Cardiovascular risk factors and diabetes generally increase your risk of dementia, too,” she says. “That’s why people are advised to lose weight, get exercise, and watch their cholesterol.”

The study’s researchers also aren’t recommending that people try to gain weight and acknowledge that more research needs to be done: “The reasons for and public health consequences of these findings need further investigation.”

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