Here's another reason to stick to your fitness plan: extra pounds can raise the risk of dementia in old age.
Older adults who are obese—defined as a body mass index (BMI) of 30 or higher—were twice as likely to develop dementia 20 years later compared to people who were at a normal weight as adults, according to a study of 1,500 Finnish adults.
While obesity is known to increase the risk of heart attack, stroke and diabetes, not to mention some cancers, few people think of extra fat as a risk to their gray matter. The study, published in The Archives of Neurology, is further evidence that what is bad for the cardiovascular system is generally bad for the brain. Previous studies have found being overweight during one's 30s and 40s is also risky.
That's bad news for the nearly 70 million Americans who are obese. Indeed, as obesity rises all over the world, public health officials warn of a future brain drain as the overweight population ages.
Although the Swedish researchers didn't pinpoint the specific ways that extra pounds may cause dementia, they found a trio of physical symptoms are an especially dangerous environment for the brain: obesity, high blood pressure and high cholesterol. In the study, people who had all three were six times more likely to develop dementia or Alzheimer's disease compared to participants who didn't.
Here's why researchers say it's important to keep tabs on these individual symptoms and keep them in check.
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Hypertension. Much of the cognitive decline that we attribute to aging may be caused by high blood pressure, which commonly goes hand in hand with obesity. Over time, high blood pressure weakens blood vessels, causing damage to the fragile inner lining of arteries. This damage not only raises the risk of stroke or aneurysm, but eventually, if not corrected, it reduces attention, learning and memory, studies show.
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Diabetes. Every year 1.3 million Americans are diagnosed with Type 2, or adult-onset, diabetes. Experts blame the obesity epidemic. Women with Type 2 diabetes have a four-fold greater risk of cognitive decline than non-diabetic women, according to a 2005 study. Diabetes seems to affect men's mental acuity to a lesser extent, for unknown reasons. A diagnosis of diabetes does not seal one's cognitive fate. Another study found that diabetics who strictly control their blood sugar reduce the risks to both the brain and the body associated with diabetes.
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Poor Diet. High cholesterol is another risk factor for cognitive problems in old age, studies find. Fat deposits in the arteries can be caused by a diet high in saturated fat, such as fatty meats and hydrogenated vegetable oils.
Previous studies have linked "good" fats—polyunsaturated fats found in olive and canola oils, fatty fish like salmon and nuts—to brain health. These fats help raise levels of "good" cholesterol (HDL, or high density lipoproteins), which helps the body get rid of "bad" cholesterol (LDL, or low density lipoproteins).
While the onslaught of health news can be frightening or downright depressing, don't give up on your goals. Research shows that losing just a few pounds can raise levels of HDL cholesterol. And losing 10% of your body weight if you are overweight can significantly reduce the risk of high blood pressure and diabetes.