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A Bigger Belly Could Lead to a Smaller Brain

Analysis by Dr. Joseph Mercola Fact Checked

bigger belly brain shrinkage link

Story at-a-glance -

  • Carrying excess weight around your midsection may affect your brain health, even leading to a concerning decline in brain volume
  • Brain shrinkage, in turn, increases your risk of memory loss and other cognitive problems
  • Participants with a body mass index (BMI) and waist-to-hip ratio (WHR) in a healthy range had an average gray matter brain volume of 798 cubic centimeters; this dropped to 786 cubic centimeters among those with a high BMI and high WHR
  • In 2010, researchers also found belly fat is associated with lower brain volume among healthy middle-aged adults

Belly fat, also known as visceral fat, is often viewed as an aesthetic problem, but if you're carrying extra weight around your middle your physical health, including that of your brain, could be at risk.

Excess belly fat is already well-known to play a starring role in the development of chronic diseases like heart disease and Type 2 diabetes. Even in people who aren't obese, excess belly fat increases the risk of death from cardiovascular problems.1 The risks of belly fat, however, do not stop there.

Researchers at Loughborough University in England have revealed that carrying excess weight around your midsection may affect your brain health, even leading to a concerning decline in brain volume.2 Brain shrinkage, in turn, increases your risk of memory loss and other cognitive problems.

Excess Belly Fat Linked to Brain Shrinkage

The study involved more than 9,600 participants with an average age of 55, who received scores for both body mass index (BMI), a flawed formula that divides your weight by the square of your height, and waist-to-hip ratio (WHR). Your waist-to-hip ratio is a more reliable indicator of your future disease risk than BMI because a higher ratio suggests you have more visceral fat — a measure BMI tells you nothing about.

The participants also received structural MRI, which provided brain images, allowing researchers to measure the volume of gray and white matter in the brain. After accounting for other risk factors, such as smoking and exercise levels, the researchers found a slight link between BMI and lower gray matter volume.

However, a much more significant connection was found for people with both high BMI and WHR. "The combination of overall obesity and central obesity was associated with the lowest gray matter compared with that in lean adults," the researchers noted.3

Specifically, participants with a BMI and WHR in a healthy range had an average gray matter brain volume of 798 cubic centimeters. This dropped to 786 cubic centimeters among those with a high BMI and high WHR.4

For the study, people with a BMI above 30 were considered obese while central obesity was determined by a waist-to-hip ratio above .90 for men and .85 for women. Study author Mark Hamer, Ph.D., said in a press release:5

"While our study found obesity, especially around the middle, was associated with lower gray matter brain volumes, it's unclear if abnormalities in brain structure lead to obesity or if obesity leads to these changes in the brain.

We also found links between obesity and shrinkage in specific regions of the brain. This will need further research but it may be possible that someday regularly measuring BMI and waist-to-hip ratio may help determine brain health."

Why Might Belly Fat Shrink Your Brain?

The featured study isn't the first time belly fat has been linked to brain shrinkage. In 2010, researchers also found visceral fat is associated with lower brain volume, this time among healthy middle-aged adults.6 As for why visceral abdominal fat may negatively impact your brain, the researchers speculated the following mechanisms:

Inflammation — Obesity is associated with inflammation, and inflammation may increase your risk of dementia. Further, higher levels of inflammatory markers have also been associated with lower brain volume, including "greater atrophy than expected for age."7

Diabetes and insulin resistance — Not only are diabetes and insulin resistance both linked to obesity, but diabetes and higher fasting glucose levels are linked with lower total brain volume.8

Hormones — One of the dangers of visceral fat is related to the release of proteins and hormones that can cause inflammation, which in turn can damage arteries and enter your liver, affecting how your body breaks down sugars and fats.

According to a study in the Annals of Neurology, "[A]dipose-tissue derived hormones, such as adiponectin, leptin, resistin or ghrelin, could also play a role in the relation between adipose tissue and brain atrophy."9

Overall, it's suggested that brain atrophy itself could be the main reason behind the association between increased visceral fat and cognitive decline and dementia.10

Obesity Also Linked to Brain Aging

Carrying excess weight throughout your body is also known to influence your brain health. For instance, a study published in the journal Neurobiology of Aging found structural changes in the brains of overweight and obese people — changes typically seen in far older individuals. In this case, it was white matter volume that decreased in relation to obesity, corresponding to an estimated increase of brain age of 10 years.11

In short, obesity may increase your risk of neurodegeneration, possibly due to the increase in inflammatory agents produced. Other research has also linked obesity with cognitive decline. For instance:

In 2008, research revealed that central obesity (belly fat) is linked with an increased risk of dementia.12

Research published in 2011 found a strong correlation between BMI and high levels of beta-amyloid, the protein that tends to accumulate in the brains of Alzheimer's patients, causing plaque buildup. It is believed that beta-amyloid destroys nerve cells, contributing to the cognitive and behavioral problems typical of the disease.13

A 14-year-long study published in July 2016 found that among people who developed Alzheimer's disease, those who were overweight or obese at the age of 50 developed symptoms nearly seven months sooner than those of a healthy weight.

Further, the onset of symptoms moved up by 6.7 months for each unit increase in midlife BMI. Those with a high BMI were also more likely to have greater amounts of amyloid proteins in their brain.14

Belly Fat Is Linked to Certain Mental Health Conditions

Your mental health may also suffer from excess belly fat, which has been linked to conditions such as anxiety and depression.

Postmenopausal women who had abdominal obesity were significantly more likely to struggle with depression than those without it (37.6 percent versus 27.5 percent respectively), leading researchers to conclude that "visceral fat accumulation was an independent and positive factor significantly associated with the presence of depressive symptoms."15

Among women, waist-to-height ratio is also associated with anxiety. Data from 5,580 Latin American women between the ages of 40 and 59 were evaluated. Overall, those with waist-to-height ratios in the middle and upper thirds were at significantly higher risk for anxiety than those with less abdominal obesity.16

Those with the greatest abdominal obesity were also the most likely to actually exhibit outward signs of anxiety. Generally speaking, a woman is considered obese if her waist measurement is more than half of her height measurement.

Losing belly fat is key for both your brain health and your overall health. Cardiovascular deaths, too, have been found to be 2.75 times higher for those of normal weight and big bellies compared to those with both a normal BMI and a normal waist-to-hip ratio.17 It's also important to recognize that monitoring your belly fat may be even more important than watching BMI.

Strategies for Targeting Belly Fat

Contrary to popular belief, focusing on abdominal exercises is not the ticket to reducing belly fat. While they will help you to build a stronger core, nutritional changes will also be necessary to burn stubborn belly fat. That being said, exercise is important too, especially fat-burning high-intensity interval training.

One of the great things about exercise is that it can help you burn fat while also benefiting your brain. Physical exercise helps build a brain that not only resists shrinkage, but also increases cognitive abilities by promoting neurogenesis, i.e., your brain's ability to adapt and grow new brain cells. Other factors linked to both brain health and belly fat include:

Sleep — Sleep problems like insomnia can have a distinct impact on your brain over time, causing it to shrink more rapidly compared to those who sleep well.18 Meanwhile, sleeping for less than five hours a night is linked to an increased rate of abdominal fat gain over five years.19 If you're not sleeping well, here are tips for a sound night's sleep.

Stress — Having elevated blood levels of the stress hormone cortisol can impair your thinking skills and memory over time.20 Previous research has also linked chronic stress with working memory impairment and an increased risk for early-onset of Alzheimer's disease.21

Chronic stress may also increase your risk for visceral fat gain over time,22 which means addressing your stress levels is imperative for both your brain and your belly.

A Ketogenic Diet Burns Fat, Boosts Brain Health

Perhaps most important of all is paying attention to your diet. While reducing your intake of processed foods and eliminating added sugars is important, I recommend going a step further and adopting a ketogenic diet if you're struggling with belly fat or interested in protecting your brain health.

When your body burns fat as its primary fuel, ketones are created, which not only burn very efficiently and are a superior fuel for your brain, but also generate fewer reactive oxygen species (ROS) and less free radical damage.

A type of ketone called beta-hydroxybutyrate is also an important epigenetic player, having significant effects on DNA expression, increasing detoxification pathways and your body's own antioxidant production. Beta-hydroxybutyrate also stimulates specific receptors on cells called g-proteins.

When these receptors are tagged by this beta-hydroxybutyrate during mild ketosis, it helps reduce the activation of pathways that lead to inflammation, and inflammation is a driver in most all chronic diseases, including Alzheimer's disease, as well as are implicated in belly fat.

For the best results, however, combine nutritional ketosis with intermittent fasting. The ketogenic diet provides many of the same health benefits associated with fasting and intermittent fasting, but when done together, most people will experience significant improvements in their health.

The details are provided in my book "Fat for Fuel," but here is a summary of how to implement these two strategies as a cohesive health program. The "Ultimate Ketogenic Diet Beginner's Guide" is also excellent reading if you're new to this way of eating.

If you're not sure whether your midsection is carrying an unhealthy amount of extra weight, your first step should be to determine your waist-to-hip ratio. To do so, get a tape measure and record your waist and hip circumference. Then divide your waist circumference by your hip circumference.

For a more thorough demonstration, please see the video below. If you fall into an at-risk zone, implementing the strategies above can help you to not only shed the fat but also improve your health significantly.

Waist to Hip Ratio Men Women

Ideal

0.8

0.7

Low Risk

<0.95

<0.8

Moderate Risk

0.96 to 0.99

0.81 to 0.84

High Risk

>1.0

>0.85