As Iʻve written in other posts, Iʻve been reading Dr. Lavieʻs The Obesity Paradox and sharing some fascinating tidbits from the book with you.
I learned another that I want to share today: there are two categories of fat: essential fat and storage fat. Essential fat is necessary for normal, healthy functioning and can be found in fairly small amounts in the bone marrow, organs, central nervous system, and muscles. For men, essential fat is about 3% of their body weight, and for women, it is about 12%. Womenʻs essential fat also has sex-specific fat, which is critical for normal reproductive function, and thus found in breasts, pelvis, hips and thighs.
Storage fat is the fat accumulated underneath the skin, in muscles and other specific areas in the body. It includes fat that protects the internal organs from injury, and women and men have about the same amounts of storage fat.
I left a teaser in my last post about The Obesity Paradox: that not all fat real estate is the same. Well, Dr. Lavie reports that "excess visceral, or belly, fat is the classic sign of being over-weight and susceptible to health risks" (p. 57). This type of fat releases fatty acids, inflammatory compunds and hormones that can lead to problems like high ʻbadʻ cholesterol and high blood pressure. It may be, researchers speculate, that visceral fat is so problematic because it is related to an overactive stress response. Visceral fat cells also release their metabolic products directly into the portal circulation: blood going from the gastrointestinal tract and spleen through the portal vein to the liver. Visceral fat is also associated with insulin resistance and accelerates the aging process.
The fat around womenʻs hips, thighs, and buttocks keeps its contents, meaning it doesnʻt release harmful metabolic products into the body. These fat cells hold on to their fat very tightly and protect the liver, but also makes it hard to lose the fat in these areas. Studies have found, too, that the body fat in these areas [hips, thighs, buttocks] actually has high value for the body, protective factors. In fact, studies have shown that the fat in these areas may actually help reduce cardiovascular risk factors, as well as lower triglyceride levels. Thus, liposuction of these areas might actually increase risk for heart disease!
Thus, as Lavie points out: "Body fat has different personalities we never knew existed and that have everything to do with our health and longevity" (p. 60).
More to come on The Obesity Paradox!