Women usually have a higher body fat percentage than men, and most of their fat accumulates in the hip and thigh area, says University of New Mexico exercise physiology instructor Len Kravitz. To add insult to injury, thigh fat is less receptive to aerobic exercise than belly fat, reports Clarence Bass, author of the "Ripped" series of workout books. While your anatomy may be your destiny, it need not be your source of despair.
Metabolism vs. Mobilization
While some people use the terms fat metabolism and fat mobilization interchangeably, they actually refer to biological processes. Fat metabolism refers to the biological breakdown of fats; fat mobilization, called lipolysis, describes the release of fat from your body's storage sites. This implies that you might metabolize fat through the digestive process and aerobic exercise, but not mobilize it to, or away from its preferred storage site. This information illustrates the myth of spot reduction exercises, equipment and creams.
Alpha vs. Beta
Fat mobilization depends on the enzyme and hormonal makeup of a given area, not on external factors such as exercise, massage and thigh-slimming creams. Hormone sensitive lipase, called HSL, and lipoprotein lipase, called LPL, are the enzymes responsible for fat mobilization. HSL sits inside your fat cells. The hormone epinephrine stimulates HSL, and the stimulation process triggers lipolysis. Epinephrine has two main types of receptors-- alpha and beta. Beta receptors stimulate fat mobilization, whereas alpha receptors prevent it. The abdominal area has more beta receptors, but alpha receptors dominate the hip and thigh area.
Alpha Thigh Conundrum
Women have a higher percentage of alpha receptor fat in their hip and thigh area, reports Ellen Blaak, author of a November 2001 study published in "Current Opinion in Clinical Nutrition & Metabolic Care." The results of Blaak's research also indicate that compared to men, women use a greater percentage of fat as energy fuel during aerobic exercise. This may explain why it is so difficult for women to lose fat around their thighs, even during high-intensity, fat-burning workouts.
The Good News
A woman might be unhappy about her thighs, but excess belly fat poses serious health risks, reports "Scientific American." These include an increased risk of diabetes, coronary artery disease, elevated triglycerides, cancer and hypertension. MayoClinic.com adds stroke, metabolic syndrome and low levels of high density lipoprotein or "good" cholesterol to the list. In contrast, research performed at the University of Oxford and Churchill Hospital in the United Kingdom found that thigh and butt fat may provide extra protection against diabetes and heart disease.