Where Your Body Stores Fat Matters More for Cardiovascular Aging Than BMI

• BMI does not distinguish between muscle and fat — This means two people with the same BMI can have very different body compositions. It does not account for where fat is stored in your body, even though decades of research show that fat distribution influences health outcomes in important ways. BMI provides a general signal but not the deeper insights needed to understand how weight is affecting your long-term well-being.⁶

• Fat is not a uniform substance — It appears in distinct depots throughout your body, each with its own properties and effects on health. Subcutaneous fat is the layer just beneath your skin that gives shape to your body. This type of fat is generally considered less harmful and, in some cases, may even play a protective role by storing excess energy away from vital organs.⁷

• Visceral fat is very different — It sits deep in your abdomen, packed around your organs such as the liver, pancreas, and intestines.⁸ This fat depot is biologically active, releasing inflammatory molecules and hormones that influence metabolism, blood pressure, and vascular function.⁹

• Liver fat is a metabolic saboteur — Sometimes called ectopic fat because it builds up in an organ never meant to store energy, excess liver fat disrupts metabolic balance and is strongly linked to insulin resistance, impaired detoxification, and widespread inflammation that extends far beyond the liver itself.¹⁰

• BMI ignores metabolic health — A study published in The Lancet redefined obesity, emphasizing that many people with a so-called “healthy” BMI still harbor dangerous levels of hidden visceral or liver fat.¹¹

These individuals may already have insulin resistance, fatty liver disease, or silent inflammation, yet their normal BMI gives a false sense of reassurance. At the same time, some people with high BMI but strong metabolic markers may not face the same risks, but are still classified as “obese” by the old system.

• It can lead to misdiagnosis and mistreatment — Labeling someone as obese based on BMI alone can send them down the path of unnecessary diets, medications, or even surgeries they may not need. Meanwhile, those who are truly metabolically unwell but maintain a “normal” weight can slip under the radar, missing opportunities for early intervention. Both overdiagnosis and underdiagnosis are harmful.¹²

• The numbers can be misleading — A BMI above 40 almost always signals excess body fat, but in all other ranges it’s a blunt tool. Researchers recommend that excess adiposity be confirmed by at least one other measure, like waist circumference, waist-to-hip ratio, or direct body fat scanning, before concluding someone is obese.¹³

• Aging hearts measured in biological time, not birthdays — With the help of machine learning, the researchers estimated each participant’s “cardiovascular age” and compared it to their chronological age, creating a metric called the “age-delta.” Age-delta reflects how much older or younger your cardiovascular system appears compared to your actual age.

• The study revealed striking sex-based differences in fat distribution — Women carried more subcutaneous and gynoid fat (fat around the hips and thighs), along with greater fat infiltration within muscle (myosteatosis). Men, by contrast, accumulated more visceral fat deep in the abdomen, more central or “android” fat in the belly region, and a higher total body fat mass.

• Age reshaped fat depots in different ways — With age, visceral fat rose more steeply in men, while both sexes experienced a steady increase in muscle fat infiltration and a modest decline in abdominal subcutaneous fat. These divergent patterns became central to the study’s exploration of how fat depots uniquely influence cardiovascular aging.

• Visceral fat is the most damaging — Visceral fat emerged as one of the strongest predictors of accelerated cardiovascular aging in both men and women. Higher volumes of visceral fat were consistently associated with a greater age-delta, meaning that arteries and heart tissues looked older than expected. In participants with diabetes, visceral fat amplified the degree of premature cardiovascular aging.

• Liver fat was another independent predictor — When researchers adjusted for age, gender, lifestyle, and conventional cardiovascular risk factors, individuals with higher amounts of liver fat still showed signs of premature cardiovascular aging. Using advanced MRI protocols to measure liver fat fraction, the study found a significant association with increased cardiovascular age-delta in both men and women.

• Fat infiltration into skeletal muscle accelerates vascular aging — When fat accumulates inside muscle fibers, it interferes with glucose metabolism and muscle function. In this study, higher levels of muscle fat infiltration were associated with a higher cardiovascular age-delta, further emphasizing that fat in unexpected locations influences how quickly your heart and blood vessels age.

• Subcutaneous and gynoid fat played different roles — Abdominal subcutaneous fat was linked with aging in men but not consistently across sexes. Gynoid fat appeared protective in women, especially in those who were premenopausal, and genetic analyses supported a causal role for gluteofemoral (gynoid-type) fat in reducing cardiovascular aging risk. Total trunk and whole-body fat mass also showed protective associations in women.

• Blood biomarkers and hormones shaped risk — The study found that certain blood markers and hormones tracked closely with whether someone’s arteries looked “older” or “younger” than their actual age.

People with higher levels of apolipoprotein B, a protein that carries LDL particles (often called “bad cholesterol”), tended to show faster cardiovascular aging. By contrast, higher HDL cholesterol (“good cholesterol”) seemed to offer some protection. A marker of long-term inflammation called glycoprotein acetyls was also tied to quicker aging.

Hormones played a role, too. Estradiol, the primary form of estrogen, was protective in premenopausal women but appeared harmful in men, while free testosterone was linked with slower aging in both sexes. Interestingly, sex hormone-binding globulin (SHBG), a protein that regulates hormone availability, was associated with accelerated aging in women.

• BMI alone missed these associations — While BMI showed a statistical link with cardiovascular aging, it was a weak predictor compared to fat distribution. The researchers noted that BMI often misclassified risk, labeling women with normal fat mass as overweight and men with high visceral fat as normal. According to them:

“We found that BMI was a weak predictor of age-delta in either sex, reflecting that accelerated aging is not predicted by overall body mass. BMI also showed a sex bias in terms of over-representing women with normal fat mass as overweight and vice versa for men.

These observations highlight the limitations and biases of aggregate measures such as BMI, and the potential for MRI-based body composition analysis, or accurate surrogate assessments, to personalize clinical risk prediction. Our data showed that visceral adipose tissue, liver fat, and to a lesser extent, muscle fat infiltration all predicted an increased age-delta in both sexes.”¹⁶

• Look beyond BMI in your health checkups — If your weight category was defined by BMI alone, it’s worth asking your health care provider about more precise evaluations. These include fasting blood sugar, cholesterol profiles, inflammatory markers, and body composition scans that show where fat is stored. Together, they provide a more reliable view of your risk.

• Pay attention even if your BMI looks “normal” — A normal BMI doesn’t always mean your body is free of risk. If you experience fatigue, signs of insulin resistance, or other unexplained health concerns, hidden fat accumulation could be the culprit.

• Measure your waist-to-hip ratio — To calculate it, divide your waist measurement by your hip measurement (using the same unit, such as inches or centimeters). Once you have the number, you can see how it lines up with risk categories:

• Another option is the waist-to-height ratio — Divide your waist circumference by your height, making sure both are in the same units. For example, if your waist measures 32 inches and your height is 64 inches, your ratio is 0.50. For adults, a healthy range is between 0.40 and 0.49. A value between 0.50 and 0.59 indicates excess weight and an increased risk of metabolic and cardiovascular disease, while 0.60 or higher signals obesity and a significantly greater risk.¹⁷

For children, this same measure can provide helpful guidance. A waist-to-height ratio below 0.46 is considered healthy between the ages of 6 and 18, while anything higher points to an increased likelihood of obesity-related health concerns later in life.

1. Check your metabolic markers — Instead of focusing only on weight, pay attention to the tests that reflect how well your body is working. A fasting insulin test, your HOMA-IR score (a measure of insulin resistance¹⁸), and simple waist-to-hip and waist-to-height ratios reveal whether you’re dealing with hidden risks such as insulin resistance or central fat storage.

2. Choose the right carbohydrates for insulin balance — Your metabolism depends on quality carbohydrates, not on avoiding them altogether. If you’ve relied heavily on low-carb or fasting plans, it may be time to reconsider. Most adults, especially those who are active, function best with 250 to 300 grams of carbs per day from whole food sources. Begin with simple, easily digested starches like whole fruits and white rice.

3. Eliminate hidden fats that disrupt metabolism — Excess seed oils (commonly called vegetable oils) fuel inflammation, impair mitochondrial activity, and encourage fat to accumulate in unhealthy ways.

To avoid them, steer clear of processed foods, restaurant meals, and even “healthy” alternatives like nut butters and seed-based snacks. Instead, use traditional fats such as grass fed butter, ghee, or tallow, and consider coconut oil for cooking. Pair these with whole, nutrient-dense foods to help restore metabolic and cellular health.

4. Correct micronutrient deficiencies — If you’re experiencing fatigue, check for deficiencies in nutrients that directly affect metabolism. Magnesium і vitamin D are two key players; without them, your body cannot manage fat efficiently.

To optimize vitamin D, aim for midday sunlight exposure — but first, remove vegetable oils from your diet for at least six months, since they heighten your risk of sunburn and skin damage. For more detailed instructions, read “Vitamin D Deficiency Complicates Autoimmune Diseases. "

5. Retrain your body to use energy efficiently — If you’ve been told that exercise alone will solve obesity, you’ve been misled — it’s only one part of the picture. The real issue isn’t lack of movement but the suppression of metabolic function driven by poor diet and toxic exposures. Put simply, most Americans are living with sluggish metabolisms, consuming unhealthy calories, and maintaining lifestyles that steadily promote weight gain.

To reverse this, strength training is especially valuable because it directs nutrients toward building and repairing muscle instead of storing fat. Complement this with daily walks to boost overall fitness. For more detail, see “Interval Walking Training — Going Beyond Step Count. "