Introduction,
Body fat distribution isn’t just about appearance; where fat is stored affects health in complex ways, with links to heart disease, diabetes, and other metabolic disorders. But what decides if you’re more likely to carry weight around your middle or in your hips and thighs? Researchers have identified a blend of genetic, hormonal, and lifestyle factors that influence this, revealing how body fat can reflect deeper biological processes and health risks.
Gender, Hormones, and Fat Storage
One of the most significant influences on body fat distribution is sex. Men and women typically carry fat in different areas due to hormonal variations, particularly the role of estrogen in women. According to Dr. Adam Collins, associate professor of nutrition at the University of Surrey, estrogen encourages fat storage around the hips and thighs in premenopausal women. “This pattern serves an evolutionary purpose,” Collins explains, “providing energy reserves useful during pregnancy and lactation.”
However, once women reach menopause, estrogen levels drop, and fat distribution begins to shift. This hormonal shift leads many postmenopausal women to adopt a more “male” pattern of fat storage around the abdomen, known as central adiposity. This shift isn’t merely cosmetic; it has profound health implications, as abdominal fat is more likely to increase risks of high blood pressure, heart disease, and diabetes.
Genetic Influences on Fat Distribution
While hormones set the stage, genetics play a substantial role in determining exactly where fat settles on the body. A significant study of over half a million people in the UK found that genetic effects on fat distribution are stronger in females than males. Certain genes influence fat storage patterns, making some women more prone to storing fat in the thighs and hips while others accumulate it around the abdomen.
Ethnicity is also a powerful factor. Dr. Collins notes that people of South Asian descent, for example, tend to have less subcutaneous fat, the kind just under the skin—and are more likely to develop visceral fat, which accumulates around internal organs and is linked to greater health risks. This predisposition may partly explain why individuals from South Asian backgrounds face higher risks of metabolic diseases like diabetes at younger ages.
The Role of Stress and Cortisol
Stress is another factor influencing body fat distribution, particularly around the abdomen. The hormone cortisol, released in response to stress, has been linked to increased abdominal fat, although the mechanism is still being studied. High cortisol levels can encourage fat to accumulate around the belly, potentially exacerbating health risks. “People with excess cortisol tend to develop this abdominal body shape,” says Dr. Fredrik Karpe, a professor of metabolic medicine at the University of Oxford. “But the relationship is complex, with other metabolic factors likely involved.”
Cortisol’s effect on fat distribution appears to be more pronounced in women, especially those experiencing chronic stress. For individuals prone to storing fat around their middle, managing stress through techniques such as mindfulness, exercise, and adequate sleep may be particularly beneficial.
The Impact of Sleep on Body Fat Composition
Sleep quality has emerged as a surprising yet significant factor in body fat distribution. Studies suggest that poor sleep patterns may be linked to higher levels of abdominal fat. While the exact relationship is still being explored, researchers believe that disrupted sleep can interfere with hormonal processes governing hunger, satiety, and fat storage. Dr. Karpe points out, however, that current evidence on sleep and abdominal fat is inconclusive and that further research is needed to confirm this link.
In any case, improving sleep quality remains an essential component of metabolic health, potentially influencing where fat is stored and reducing the risk of conditions associated with abdominal fat, such as insulin resistance and heart disease.
Subcutaneous vs. Visceral Fat, What’s the Difference?
Not all body fat is created equal. There are two primary types of fat: subcutaneous and visceral. Subcutaneous fat is the fat stored just beneath the skin and is typically less harmful to health. You can feel it by pinching your skin, and it often acts as an energy reserve and an insulator for the body. On the other hand, visceral fat, also known as “deep” fat, is stored around internal organs in the abdomen. This fat is metabolically active, releasing compounds that increase inflammation and contribute to various health issues, from insulin resistance to heart disease.
Dr. Collins explains that visceral fat storage acts as a sort of overflow system. “When the body’s capacity to store fat subcutaneously is exceeded, it begins storing fat viscerally,” he says. While this system helps manage temporary surpluses, long-term accumulation of visceral fat is problematic, leading to what researchers call “metabolic spillover.” This spillover effect can disrupt normal metabolic functions, increasing the risk of diabetes and other metabolic disorders.
Genetics and ethnicity also influence visceral fat levels. Research has shown that people from certain backgrounds, such as those of South Asian descent, tend to accumulate more visceral fat than their Caucasian counterparts, which may partially account for their increased susceptibility to metabolic diseases.
Lifestyle Choices, Diet and Exercise Matter
While genetics and hormones set certain limits, lifestyle factors can still play a significant role in managing fat distribution. Studies suggest that regular exercise and a balanced diet can help reduce both total and visceral fat, even if genetic predispositions favour abdominal fat storage. Physical activity, in particular, creates a metabolic effect that can reduce visceral fat and improve liver health.
For men, exercise tends to target abdominal fat more directly, leading to more substantial reductions in central adiposity with regular workouts. Dr. Karpe notes that weight loss in men often comes from the stomach, which can lower health risks associated with abdominal fat. However, people of South Asian descent may not see the same targeted abdominal fat loss and may require more specific lifestyle changes to manage health risks.
Diet also plays a role, as diets high in processed sugars and refined carbohydrates are linked to increased abdominal fat. Instead, a diet rich in whole grains, lean proteins, and fibre can support fat loss, particularly in the abdominal area.
Can We Control Body Fat Distribution?
Ultimately, the science behind fat distribution shows that we have only limited control over where our bodies choose to store fat. While diet, exercise, and other lifestyle factors can help reduce total and visceral fat, they cannot completely override genetic predispositions. If someone is more prone to storing fat on their thighs or belly, they may not be able to change this entirely. However, a healthy lifestyle can reduce the amount of deep, visceral fat that carries the greatest health risks.
Recent research in genetics and metabolism highlights that while we may not have full control over body fat distribution, understanding how different factors influence fat storage can empower us to make choices that support overall health. By targeting lifestyle changes, such as managing stress, prioritizing sleep, and adopting a balanced diet and exercise routine, individuals can mitigate the potential negative impacts of visceral fat, regardless of genetic predispositions.
References
- Collins, A., et al. (2023). Hormonal regulation of body fat distribution: The role of estrogen. Journal of Endocrinology and Metabolic Health.
- Karpe, F., et al. (2022). Stress, cortisol, and abdominal fat: A comprehensive review. International Journal of Obesity, 46(1), 45-57.
- Pathak, N., et al. (2021). Ethnic differences in fat distribution and metabolic health. Metabolic Journal of Clinical Research, 39(3), 290-300.
- Mozaffarian, D., et al. (2020). Visceral fat and metabolic disease risk. Annual Review of Clinical Nutrition, 12(2), 221-240.
- Willett, W., et al. (2019). Diet, exercise, and visceral fat: A meta-analysis. The American Journal of Clinical Nutrition, 110(2), 311-318.
- McLellan, A., et al. (2021). Sleep quality and body composition: Implications for metabolic health. Sleep Medicine Reviews, 59(5), 341-348.
- Willett, W., et al. (2019). The role of subcutaneous and visceral fat in cardiometabolic health. Nature Medicine, 25(6), 922-933.