Why Are Men Always So Warm?

"Being a male, or more accurately, having lots of testosterone circulating through the body, whether you have lots of big muscles or not, complicates the impact of exercise and energy production on mitochondrial function and your body's health. Testosterone increases the energy expenditure from muscle mitochondria, leading to an increase in the number of mitochondria within each muscle and an increase in the production of ATP. Much of the energy used for the increased production of ATP is drawn from the body's stored fat."

"Testosterone alters how males metabolize food and increases the amount of heat their muscles produce during normal respiration. Testosterone, due to its effects on a specialized protein, called Uncoupling Protein or Thermogenin (referring to its ability to produce heat), makes the normal food-to-energy conversion process in mitochondria become inefficient-that is, cells waste more energy as heat, making men feel warm."

"Many of my male students participate in some form of daily exercise routine. Every year I warn them about the consequences of too much exercising, but they are young and feel immortal and usually choose to ignore my advice. Lacking both testosterone and significant muscle mass (typically), women tend to produce less body heat from their food; consequently, it is usually much harder for women to lose weight than it is for men."

Testosterone raises muscle mitochondrial activity, increasing ATP production and the number of mitochondria per muscle. Much of the extra ATP demand is met by mobilizing stored fat. Testosterone promotes expression or activity of Uncoupling Protein (Thermogenin), causing mitochondrial respiration to become less efficient and waste energy as heat, which makes men feel warmer. Greater mitochondrial activity in males and especially in muscular individuals increases heat radiation and free radical production. Females, with lower testosterone and typically less muscle mass, produce less heat from food and often face greater difficulty losing weight.

Read at Psychology Today