Hidden fat inside the body is secretly aging your heart

Most people think of fat as what they can see in the mirror. Yet hidden fat stored deep inside the body tells a different story. Scientists are uncovering its surprising role in how quickly our hearts age, and the findings reveal a complex picture of health that extends beyond weight alone.

Aging is the strongest risk factor for heart disease. However scientists have long puzzled over why some people’s hearts age faster than others.

New research highlights visceral fat, the fat wrapped around organs, as a key player. Unlike fat under the skin, this invisible type can accelerate wear and tear on the heart and blood vessels.

Scientists from the Medical Research Council (MRC) Laboratory of Medical Sciences in London analyzed data from over 21,000 participants in the UK Biobank.

Organ fat ages hearts

Using whole-body imaging and artificial intelligence, researchers compared organ scans to track how fat distribution related to heart aging. Each participant was assigned a “heart age” to show how their cardiovascular system compared with their actual age.

The findings were clear. People with more visceral adipose tissue showed signs of faster heart aging. This fat surrounds organs like the stomach, intestines, and liver, often hidden even in people who look slim.

Blood tests also revealed a link with higher inflammation, which is closely tied to premature aging. The study also showed that infiltration of fat into muscle tissue and excess liver fat added to the risk.

Apple vs. pear risk

The research also found that sex and body shape play a role. Men with belly fat, often described as an “apple” shape, showed stronger signs of early heart aging. Women, however, displayed a different pattern.

A “pear” shape, with fat on the hips and thighs, seemed protective against heart aging. Genetic analysis also suggested that gluteofemoral fat in women may causally reduce cardiovascular aging. Higher estrogen levels in premenopausal women added further protection, reinforcing the role of hormones.

“We have known about the apple and pear distinction in body fat, but it hasn’t been clear how it leads to poor health outcomes,” said Professor Declan O’Regan, who led the study. “Our research shows that “bad” fat, hidden deep around the organs, accelerates aging of the heart.”

“Some types of fat could protect against aging – specifically fat around the hips and thighs in women.”

BMI misses hidden heart risks

One striking finding was that body mass index (BMI) is not a reliable measure of heart aging. People in the same BMI category often had very different fat distributions.

For example, some higher-weight individuals carried fat in safer areas, while others had high levels of visceral fat despite appearing healthy.

This weak link between BMI and biological aging stresses the importance of advanced imaging or improved surrogate tools to identify hidden risks.

Therapies for heart aging

The study suggests a new way to think about heart health. Being fit and active helps, but visceral fat still poses hidden risks.

“The goal of our research is to find ways to increase healthy lifespan,” said O’Regan. “While being active is important, we found that hidden fat could still be harmful even in fit people.”

“In the future, we plan to investigate how drug therapies, such as GLP-1 inhibitors (e.g., Ozempic), could improve not just diabetes and obesity but also target the aging effects of hidden visceral fat.”

The uploaded study also highlighted how hormones shape fat distribution. Estradiol in premenopausal women was linked to slower cardiovascular aging.

Scientists propose that this hormone may drive fat storage to the hips and thighs, offering protective benefits. These findings support the idea that hormone replacement therapies could play a role in managing cardiovascular aging in women.

Hormones and health

The British Heart Foundation, which supported the study alongside the Medical Research Council and the National Institute for Health and Care Research, emphasized the findings.

“We already know excess visceral fat around the heart and liver can lead to increased blood pressure and high cholesterol,” said Professor Bryan Williams, OBE. “It is concerning that it could also help speed up aging of the heart and blood vessels.”

“As the pattern of fat distribution typically seen in women’s bodies is linked to estrogen, that hormone may be key to future therapies developed to tackle heart aging. Eating a healthier diet and becoming more active can help reduce visceral fat levels.”

Key lessons on heart and age

This research highlights that not all fat is equal. While some fat types can help protect the heart, hidden visceral fat acts like a silent threat.

By mapping its role in aging, scientists hope to open new pathways for treatment and prevention. For now, understanding where fat is stored may be just as important as knowing how much there is.

The study is published in the European Heart Journal.

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