Here is a short article I posted on FI concerning the performance-enhancing advantages of getting lean. Beyond looking good in the mirror, here are seven more reasons for losing the lard;
Improved insulin sensitivity
An increase in glucose in the bloodstream signals the pancreas to increase the secretion of insulin; This hormone attaches to cells, removing glucose from the bloodstream so that it can be used for energy.
In insulin resistance (which can be caused by overeating and excess bodyfat), the body's cells have a diminished ability to respond to the action of the insulin hormone. To compensate for the insulin resistance, the pancreas secretes more insulin. Over time insulin resistance can cause high blood sugar or even diabetes.
Excess body fat (especially around the midsection) promotes insulin resistance. In muscle cells, insulin resistance inhibits the storage of glucose as muscle glycogen and the glucose is instead stored as fat.
By reducing bodyfat (especially visceral fat), insulin sensitivity is improved, results in more glucose stored as muscle (and liver) glycogen and less as fat. This means better pumps, more energy during training and better recovery (as nutrient and amino acid uptake to the muscles is improved).
Reduction in cortisol levels
Obesity has been linked to oversecretion of cortisol. Increased intracellular activity of 11beta-HSD-1, which catalyzes reduction of cortisone to cortisol, has been reported in obese mice and humans. As you are all aware of, cortisol excess is bad news when it comes to muscle, but it also causes rises in blood sugar (insulin resistance again!) and blood pressure, supresses the immune system, lowers bone formation, inhibits protein synthesis, blocks uptake of amino acids by the muscle and causes the breakdown of glycogen.
Definitely not something you want an excess of in your body.
Researchers have shown that circulating mononuclear cells - the body's monocytes (the largest type of white blood cell) and lymphocytes -- exist in a proinflammatory state in obese persons.
Weight gain is associated with an increase in pro-inflammatory signals from adipose tissue. These signals in turn may be responsible for further increases in weight and body fat. What we have is a vicious circle where fat causes more fat gain, inflammation leads to insulin resistance (yet again!), increasing body fat which begins the cycle again.
Chronic inflammation may lead to diabetes, heart disease and premature aging, as well as a negative effect of athletic performance due to an increase in oxidative stress.
Reduced estrogen levels
Obesity is associated with increased aromatization of androgen precursors to estrogens. Fat cells produce and secrete estrogen and the enzyme aromatase. When we gain weight the increased stored fat produces more aromatase. which is responsible for converting androstenedione and testosterone into estrogen. Higher levels of estrogen also promote insulin resistance (arrgh!)
Research supports a link between estrogen and regulation of obesity, especially the dangerous accumulation of abdominal fat linked to heart disease, diabetes, and cancer. Not to mention gyno.
Increase growth hormone secretion
Growth hormone secretion is markedly blunted in those with excess bodyfat. A reduced GH half-life, frequency of secretion and daily production rate of the hormone are all seen, also in these patients GH secretion is impaired in response to all traditional pharmacological stimuli. Impaired responsiveness to growth hormone-releasing factor in obese people is mediated by an impaired pituitary response. When weight is lost the release of growth hormone is improved greatly.
Increase testosterone levels
Obesity has been identified as the most important determinant of total testosterone over time, with levels 25% lower in
obese men when compared to their nonobese counterparts. Testosterone has an inverse relationship with obesity, especially visceral obesity; adipose tissue extensively metabolizes testosterone to oestrodiol, thus obese men also have increased extraction of testosterone because of aromatization. Oh, and this also causes erectile dysfunction in overweight men.
Obtaining quality sleep seems to be a problem for many heavier strength athletes.
A recent study by Columbia University found that people who slept four hours or less per night were 73% more likely to be obese. Sleep apnoea is another problem associated with excess fat. If you're obese, you're more likely to have sleep apnoea;
having too much fat in your neck can cause sleep apnoea. When you sleep, the muscles in and around your windpipe relax, causing the tissues to block your airway and briefly stop you breathing, which causes you to wake up each time your breathing stops.
Losing 10 percent of your weight can make sleep apnoea half as severe.