Stubborn Fat: New Ideas - by David Grisaffi
Stubborn Fat: New Ideas - by David Grisaffi: "When it comes to the physical make-up of men versus women, many of the differences are obvious. Men, on average, are 10-15% larger than women, weigh 20% more, and are 30% stronger (especially when considering upper body strength). Testosterone is one of the major hormones active in a man's body. Men also produce more HGH (human growth hormone). Testosterone stimulates muscle enlargement and bone growth and also raises the level of red blood cells in a man's blood stream.
What you may not know, however, is that all of these factors combine to make oxygen much more available to a man's cells than a woman's cells. That means a man could be working at 50% of his capacity during physical activity, but a woman would have to be working at 70% of her capacity in order to keep up. It is not as easy for her cells to absorb oxygen. This is due partly to the fact that women have a smaller percentage of lean tissue (muscle, organs, etc.) and a much higher percentage of body fat. Though this is detrimental in a short sprint, a higher percentage of fat means that women can power their cells longer from their body's reserves without stopping to eat or drink in order to refuel. This may translate into greater endurance. Studies comparing men and women in running, swimming, and speed skating have all shown that the differences"