Epidemiological studies show that the distribution of body fat affects the risk of developing various diseases, regardless of total body mass or the percentage of body fat. In other words, it’s not just body weight, but the type and distribution of fat on the body that significantly impacts health.
Obesity is associated with excessive accumulation of fat tissue, mainly under the skin (called subcutaneous fat) or around internal organs. This is known as visceral fat, though it can also be found in bone marrow (yellow bone marrow), cheeks, periarticular regions of the body, and tissues such as muscles and vital internal organs (ectopic fat deposition).
About 80-90% of fat is subcutaneous fat, which accumulates around the abdomen, upper back, buttocks, and thighs. Experts emphasize that in this case, the stored fat is just beneath the skin and does not directly interact with internal organs. In contrast, visceral fat accumulates mainly in the abdominal cavity, close to major organs, including the liver and intestines.
Unlike subcutaneous fat, visceral fat directly affects the body’s functioning by releasing components like free fatty acids and adipokines (hormone-like substances secreted by white fat cells) into the portal circulation (part of the circulatory system). In this way, visceral fat influences our metabolism. Visceral fat is believed to account for 6 to 20% of total body fat, with men typically having higher levels than women. Additionally, there is a small amount of visceral fat around the heart, known as epicardial fat. For practical purposes, human fat tissue is classified into lower body fat, upper body subcutaneous fat, and intra-abdominal (visceral) fat.
What Does Fat Distribution Say About Our Health?
When it comes to cardiovascular disease risk, fat distribution is increasingly being recognized as a more important health parameter than overall obesity. There is strong evidence that visceral fat is the most harmful, particularly excess fat that manifests as an expanding waistline (abdominal obesity). Fat accumulation in the upper body increases the risk of dyslipidemia, hypertension, type 2 diabetes, sleep apnea, and certain cancers. Fat tissue can also secrete inflammatory chemicals called cytokines, which promote insulin resistance. It is also important to note that large amounts of subcutaneous fat can increase the risk of diseases, though not as significantly as visceral fat.
The size and distribution of fat are influenced by sex hormones, especially estrogen and testosterone, as well as age (visceral fat tends to increase with age) and genetics (though researchers have yet to find answers to many questions related to this). Environmental factors, such as alcohol consumption and smoking, also affect fat distribution on the body.
