The Surprising Ways Body Weight Affects Brain Health

Body weight and brain health

The brain is the very essence of who we are, so we want it to stay healthy. But just as other organs change with age, cognitive challenges can arise with aging. Some of these changes are benign and ones that everyone experiences at times. For example, it may take you a bit longer to remember someone’s name or the name of a movie you saw a few months ago. But some people experience more serious cognitive issues ranging from mild cognitive impairment to dementia. The most common form of dementia is Alzheimer’s disease.

With the brain being so complex, scientists still don’t completely understand what causes Alzheimer’s disease. Multiple factors, including genetics, increase the odds of developing it. Now a study shows the likelihood of developing cognitive problems might be partially related to body weight.

Body Weight and Brain Health

Obesity is a risk factor for a number of age-related health problems, including cardiovascular disease, type 2 diabetes, and some forms of cancer, but carrying too much body fat may also play a role in brain health and cognitive function.

In a new study, researchers looked at the image studies of over 17,000 individuals. These scans use single-photon emission to look at brain activity and blood flow to the brain. Upon looking at the scans, the researchers found patterns of reduced blood flow in various areas of the brain, including ones associated with cognitive processes. The areas of decreased blood flow were more numerous in people who had a higher body weight and was proportional to how much extra body weight they carried.

Why is this important? Decreased blood flow to the brain is a strong marker of increased risk for developing Alzheimer’s disease. Other health conditions involving the brain such as depression, certain mental disorders, addiction, and brain injury are also linked with reduced blood flow to the brain. Therefore, avoiding excess body weight may preserve brain health and slow brain aging by preserving blood flow to the brain.

This isn’t the first study to show that being overweight or obese lowers blood flow to the brain, so it’s further confirmation that carrying too much body weight can be a problem for brain health and cognitive function.

Other Conditions that Reduce Blood Flow to the Brain

Other health conditions that reduce blood flow to the brain also increase the risk of developing Alzheimer’s disease. Some of these include hypertension, atherosclerotic heart disease, sleep apnea, and lipid abnormalities. Therefore, it’s important to live a lifestyle that lowers the risk of developing these health problems and treating them if you already have one or more chronic health issues.

Lifestyle Factors That Boost Blood Flow to the Brain

If decreased blood flow to the brain is a risk factor for brain aging and dementia, lifestyle factors that increase the delivery of oxygen to the brain should be beneficial. One of the most effective lifestyle habits for delivering more oxygen to the brain is aerobic exercise.

When you launch into an aerobic workout, your heart begins beating faster and blood vessels open up to allow more blood and oxygen to reach your brain and other tissues. With continued aerobic training, your heart becomes a more efficient pump, allowing greater oxygen delivery. But when you take a long break from exercise, you lose this benefit. In fact, MRI brain imaging of athletes found that when they stopped exercising, the blood flow to eight regions of the brain dropped by 20 to 30%, including regions involved in cognitive function and memory.

Other Ways to Boost Blood Flow to the Brain

Exercise is one of the best ways to boost blood and oxygen delivery to the brain, but what you eat and drink matters too. For example, leafy greens contain compounds that increase nitric oxide production by the inner walls of blood vessels. Nitric oxide helps vessels expand so they can maximize blood flow to organs and tissues. Make sure you’re eating enough fruits and vegetables too. They’re a good source of potassium and magnesium that helps with blood pressure control. Also, make sure you’re drinking enough fluid. Dehydration can reduce blood flow to organs, including your brain.

Slow Brain Aging and Lower Your Risk of Dementia

It would be too simplistic to say that staying a healthy body weight and being physically active is enough to prevent Alzheimer’s disease. It’s a complex disease that we don’t fully understand and there are genetic factors that increase the risk. However, research shows that not all people at strong genetic risk develop the disease. Due to epigenetic factors, lifestyle can make a difference.

Here are some lifestyle changes that may reduce the odds of developing Alzheimer’s disease:

  • Avoid head injury (wear a helmet when biking etc.)
  • Eat a Mediterranean-style diet
  • Challenge your brain by learning a new language or a new instrument
  • Sleep between 7 and 8 hours per night
  • Manage stress
  • Don’t smoke
  • Avoid excessive use of alcohol
  • Stay social (Loneliness is a risk factor)
  • Spend time in nature
  • Control blood sugar, blood pressure, lipids

The Bottom Line

Carrying excess weight, even without being obese, may increase your odds of developing cognitive problems. This research suggests that the reason may be related to reduced blood flow to the brain. Plus, fat cells produce inflammatory chemicals called cytokines that are harmful to the brain and other tissues. But make sure you’re leading a brain-healthy lifestyle by optimizing sleep, managing stress, learning new things, staying physically active, and controlling risk factors and chronic health problems. Don’t let your brain age faster than the rest of your body! Treat it well.



  • Daniel G. Amen, Joseph Wu, Noble George, Andrew Newberg. Patterns of Regional Cerebral Blood Flow as a Function of Obesity in Adults. Journal of Alzheimer’s Disease, 2020; 1 DOI: 10.3233/JAD-200655.
  • Harvard Health Publishing. “Stopping exercise for 10 days can decrease brain blood flow”
  • Arch Neurol. 2003;60(3):359-365. doi:10.1001/archneur.60.3.359.
  • NeuroImage: Clinical. Volume 20, 2018, Pages 650-654.
  • com. “Imaging study offers clue to how obesity can increase Alzheimer’s risk”
  • org.UK. “How are changes to blood flow to the brain linked to memory and thinking problems?”
  • org. “Putting on weight slows blood flow to the brain, increasing Alzheimer’s risk”


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