The Risks of Being a Male

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. 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 on 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. So far, this all sounds great.

Unfortunately, the testosterone-driven mechanisms that control the metabolism of fat for energy have significant consequences for males. 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, makes the normal food-to-energy conversion process in mitochondria become inefficient—that is, cells waste more energy as heat, making men feel warm almost all of the time. 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.

The male body, particularly all of those muscles, is capable of wasting a considerable number of consumed calories as body heat. This explains why the principal method of dieting for many of my young male students is to eat anything they want and then efficiently exercise the calories away. Or, they could do nothing at all. Males, to the chagrin of females, can lose weight by simply sitting still and watching football. In contrast, women, who lack the mitochondrial uncoupling actions of testosterone, are forced to lose weight the old-fashioned way, by not consuming as many calories.

Unfortunately, for males, wasting calories in order to produce heat has some negative long-term consequences. First of all, males need to consume more calories per day than do females; consequently, males generate more harmful reactive oxygen-free radicals--ROS. These ROS are harmful to the body and negatively affect men’s health and reduces their longevity, as compared to women.

Males of many different species, including spiders, flies, the birds and the bees, generally do not live as long as females. This is true even for species with a very short life span, such as a fly. Male flies of one species have an average maximum life span of five days; the females of the same species have an average maximum life span of seven days. In contrast, females waste less energy as heat, need to consume fewer calories every in order to survive, and produce fewer ROS; all of which benefits their overall brain health and longevity (for longer discussion on this topic, see the reference below). If ROS are so harmful, why does your body produce them? Because you have no choice. If you have stopped making ROS, you are probably dead.

You can easily see the paradox here. Males and females must eat to survive, however, accessing the energy stored in food requires oxygen which leads to the production of ROS. Thanks to testosterone and all of those mitochondria in muscles, males generate more ROS and, all things being equal, always die sooner than females. Now you can understand why exercising does not slow down normal aging. However, modest exercise, such as a daily stroll in the park, will allow you to age more slowly than extreme exercising.