For years, the mainstream has been pointing their fingers at all kinds of things that could cause Alzheimer’s disease.
Your diet… exercise habits… and mostly your “faulty” genes, to name a few.
And when they aren’t jumping to conclusions about your future using these factors, they rely on an outdated metric that causes panic, but maybe not memory problems.
I’m talking about the Body Mass Index (BMI) scale.
What Is BMI?
Body Mass Index (BMI) is a numerical value derived from your height and weight. It’s calculated by dividing a person's weight in kilograms by the square of their height in meters (kg/m²).
BMI is commonly used to categorize people into different weight categories, such as underweight, normal weight, overweight, and obesity. It serves as a general indicator of whether you have a healthy body weight for a given height, but here’s a very important point: it does not directly measure body fat or distribution.
Think of BMI as that friend who gives you a general heads-up about your health but isn't going to dive into the nitty-gritty details. It's a conversation starter, not the whole conversation. It might say, "Hey, you might want to keep an eye on things," or "Looking good, keep it up!" But for the full story? You'll need to chat with a doctor and probably run a few more tests.
Doctors Still Use BMI for Disease Prevention
For decades, doctors have pointed to BMI to predict everything from diabetes to heart disease. Now, thanks to new research, we know that using BMI is all wrong when it comes to your body weight, body fat, and Alzheimer’s.
It’s no secret that carrying extra weight harms your body and mind. Extensive research shows that being overweight can impact your heart… your blood sugar… your liver… and even your memory sharpness. (I’ve written about how certain genes linked to obesity are also linked to Alzheimer’s here.)
So, there’s no arguing that excess body fat plays a key role in the development of Alzheimer’s.
However, there’s an argument for the inaccuracy of how the mainstream measures body fat regarding Alzheimer’s prediction.
The Belly Fat – Brain Connection
Previous research shows that belly fat—especially the kind stored around your organs—is linked to brain aging.
Unfortunately, BMI doesn’t measure for the specific type of fat. Instead, it uses your total weight, including healthy fat, muscle, and bones. Without identifying which type of fat increases your BMI, there’s no way to know if you’re at risk for memory issues.
New research could change all of this….
For the study, 204 participants underwent abdominal fat scans and cognitive testing, 142 of which also completed brain scans.
At the end of the research period, scientists found that fat stores in certain areas of the abdomen were linked to lower brain volumes and reduced cognition. Specifically, higher volumes of fat found around the liver were linked to lower amounts of gray matter in the brain.
Higher volumes of fat around the pancreas were associated with lower cognition, decreased executive function, memory issues, and smaller brains. Finally, having more belly fat overall was linked to lower brain volume in areas related to cognition and memory.[1]
Again, this isn’t the first time that belly fat has been linked to dementia risk. And this isn’t the first study to indicate that BMI isn’t the most accurate way to predict Alzheimer’s risk.
Another study of 6,582 people aged 50 years found that people whose BMI was 30 or higher—which is considered obese—at the start of the study had a 31 percent greater risk of dementia at an average follow-up of 11 years than those with normal BMIs.
But here's where it gets interesting. The scientists also looked at how big around people's waists were. When they considered both BMI and waist size together, they found that obese people were 28 percent more likely to have memory problems.
So, what does this mean? It suggests that being very overweight might increase your chances of having memory problems when you get older. But it's not just about how much you weigh - where your body stores that extra weight (around your waist) is more important than BMI.
This means that your doctor needs to look at the WHOLE PICTURE when it comes to extra weight and your Alzheimer's risk instead of relying on an outdated tool.
Why Does Belly Fat Matter to Your Memory?
Experts report that belly fat impacts the brain through many metabolic pathways. Excess belly fat, particularly visceral fat, is dangerous for memory due to its association with increased inflammation and insulin resistance. This type of fat surrounds vital organs and releases inflammatory chemicals, which can affect the brain.
Chronic inflammation and insulin resistance can impair brain function, including memory. Additionally, belly fat is linked to a higher risk of developing conditions such as Type-2 diabetes, cardiovascular disease, and metabolic syndrome, all of which are associated with cognitive decline and an increased risk of dementia.
Our Takeaway
If you’re worried about your brain health and weight, talk to your doctor about doing an abdominal scan. This will give you a clearer picture of where your fat deposits are… and how they may impact your brain health and memory.
For now, there’s little doubt that the mainstream will continue to rely on BMI measurements, but studies like these could mean that things are moving in the right direction when assessing belly fat and dementia risk.
So next time you hear about BMI, or even measure your own using one of the many online BMI calculators, remember—it's a useful tool but not the whole toolbox. BMI is nothing more than a quick and easy way to get a ballpark figure on where you stand weight-wise, but it won't tell your whole health story. Use your BMI as a starting point for your health and wellness, but don't let it be the final word on your health journey.
- Golan Shekhtman S, Boccara E, Ravona-Springer R, Inbar Y, Zelicha H, Livny A, Bendlin BB, Lesman-Segev O, Yore I, Heymann A, Sano M, Mardor Y, Azuri J, Schnaider Beeri M. Abdominal fat depots are related to lower cognitive functioning and brain volumes in middle-aged males at high Alzheimer's risk. Obesity (Silver Spring). 2024 May;32(5):1009-1022. doi: 10.1002/oby.24004. Epub 2024 Feb 27. PMID: 38410053. https://onlinelibrary.wiley.com/doi/full/10.1002/oby.24004