Is there a link between obesity and brain health?

April 27, 2021 in Health Risk Management  •  By Miles Varn, MD

You’re probably aware that obesity can have a negative effect on many aspects of your health, from increasing your risk of developing heart disease and diabetes to a higher risk of arthritis, gallbladder disease, and some types of cancer. But you may not know that obesity can affect the health of your brain.

The exact mechanism that causes changes in brain function in people who are obese has not been definitively identified. Some research has found an association between decreased blood flow to the brain and lower brain activity. This has been linked to a possible increased risk for developing dementia and Alzheimer’s disease.

One study looked at more than 35,000 scans from single-photon emission computerized tomography (SPECT) of 17,000 adults. As body mass index (BMI) increased, blood flow to the brain was observed to be lower when participants were resting and when they were performing a task that required concentration.

In addition to an increased risk of cognitive problems due to reduced blood flow to the brain, other researchers have noted an association between decreased blood flow and the risk of ADHD, depression, anxiety, and bipolar disorder.

Another study found an association between higher BMI and waist to hip ratio measurements and a decrease in the overall size of the brain. The amount of gray matter in the brain, which controls movement, memory, and emotions, also decreased. The researchers, however, were not able to figure out if obesity caused these brain changes or if pre-existing differences in brain structure caused the people to be obese.

Take steps to protect the health of your brain

By taking proactive steps towards a healthier lifestyle and healthy weight, you can protect your brain and take charge of risk factors that can negatively impact brain health. Here’s how you can get started:

  • Make exercise a priority. Several studies have noted a strong association between taking part in regular physical activity and a lower risk of cognitive decline. Although why this association exists hasn’t been shown definitively, they posit that exercise both increases blood flow to the brain and levels of the hormone irisin, which improves the metabolism of glucose (sugars) and lipids (fats). Exercise is also associated with a decrease in inflammation in the body.
  • Choose a healthy diet. A Mediterranean diet has been linked with both a lower risk of heart disease and the slowing of age-related cognitive decline in older people. Choose at least three servings of whole grains, a leafy green vegetable, one other vegetable, and berries every day. Eat beans and legumes at least every other day. Choose poultry and fish for protein. And for snacks, try raw nuts. Limit butter, cheese, and fried food.
  • Focus on healthy sleep. Some studies have found a correlation between poor quality or too little sleep and an increased risk of Alzheimer’s disease. During sleep, cerebrospinal fluid rinses waste like amyloid, which builds up in the brains of people with Alzheimer’s, out of the brain. Adults should get between seven and nine hours of sleep a night to give their brains time to recoup.
  • Be heart healthy. Researchers have found that taking steps to keep your heart healthy, like lowering your blood pressure, also benefits the health of the brain. Lower blood pressure has been linked to a lower risk of several types of dementia and overall cognitive decline. Researchers are also looking at whether lowering cholesterol levels can reduce your risk of dementia.
  • Don’t smoke. A number of studies have shown that smoking is linked to a higher risk of cognitive problems as you age. If you quit, you can reduce your risk to the same level as people who never smoked.


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