What role has body fat evaluation in human function and performance?

In modern society obesity has become a growing concern for the health care practitioner. The most recent data from the American National Center for Health Statistics show an increasing trend, that 30% of U.S adults from 20 years of and older suffer from obesity. That’s over 60 million people! What’s even more alarming is that this increasing trend is not limited to adults, the percentage of children who are deemed as overweight has tripled since 1980, where now 16% of children between the ages of 6 and 19 are classed as overweight. This trend in the increase of the number of people who are overweight and or obese raises great concern for the health and well being of modern society and is on the verge of becoming an epidemic.

As stated previously a high percentage body fat can increase the risk of serious health problems such as hypertension, type 2 diabetes, depression, hyperlipidemia and heart disease, osteoarthritis, respiratory problems, and even some cancers. The evaluation of percentage body fat on a habitual basis (as part of an annual medical) may be a vital tool to help minimize the risk of such complications.

The evaluation of percentage body fat can be used as a guide as to what may lie ahead for those on the higher percentage body fat scales. A recent study entitled The Influence of Excess Adiposity on Exercise Fitness and Performance in Overweight Children and Adolescents hypothesized that the increased metabolic cost of having to move a greater mass, was the primary factor limiting overweight adolescents when they undertake sustained exercise, and also that the effect of diminished cardio respiratory reserve would be smaller but still important and warranted further study. The study shows that even as a child or an adolescent increased body fat percentage is having a direct effect on human function which can only diminish with time if not rectified.

Through body fat evaluation the health care practitioner can more readily prescribe suitable measures for the individual to obtain an optimum level percentage body fat, whether it be to counter act an elevated body fat percentage or merely to maintain ones current levels. However the evaluation of percentage body fat is not limited to those who are overweight or suffering from obesity, it is an essential part of the process when treating patients with Anorexia Nervosa. In a recent study on the refeeding of adolescent girls, bioelectrical impedance analyses was used to monitor body composition throughout the study. The initial BMI for the girls suffering from Anorexia Nervosa was 15.5 ± 1.1kg/m² and had risen to 17.4±0.7 kg/m² by the end of the 15 week trial period. A significant finding was that despite a 70.7% gain in fat mass, the patients were still categorised as underweight.

In most athletic events the athletes must move their own body mass through a series of movements as quickly and efficiently as possible, excessive body fat generally has an adverse effect on performance of a variety of motors skills and cardiovascular endurance. From a mechanical perspective, excess body fat is a inert load that must be moved, a dead weight that provides no function.

William “The Refrigerator” Perry, NFL legend, who played for the Chicago Bears during the 1980’s & ‘90’s, turned up to the 1988 summer training camp weighing in at 375lbs (170.5kg) some 55lbs (25kg) over his mandated playing weight. Not only is this of great concern regarding the ability to perform on the field at such an excessive weight, but also of even greater concern is the possible health risks associated with such extreme levels of obesity.
Another famous American athlete, Chris Taylor a U.S Olympic wrestler competed at a bodyweight of 400 – 450lbs (182 – 204.5kg) He died in his sleep at age 29.

Effects of excess body fat are especially apparent when comparing obese to non-obese individuals. In a recent study on the comparison of physical fitness between obese and non-obese Flemish youths, a strong correlation was found between obesity and inferior performance results on all tests which required propulsion or lifting of the body mass. Tests included, standing broad jump, sit ups, bent arm hang, speed shuttle runs, and endurance shuttle runs. The sample group was divided into those who were obese and non-obese using both Body Mass Index and Skinfold measurement. A similar study comparing the performance of obese and non-obese Belgian girls on most measures of physical performance; including strength, flexibility, and motor performance, found similar results. The obese girls under performed in comparison to non-obese in muscular endurance, trunk strength, lower back flexibility, and relative arm strength (based on % bodyweight).

From the information above we are lead to conclude that not only does excess body fat negatively influence the ability to perform physical tasks, it also poses a serious threat to health and place the obese individual at a high risk for serious health complications. The evaluation of body fat is therefore plays a vital role in the evaluation of human function and performance.

To read more about body fat measurement, check out Brian’s article Body Fat – Does Yours Measure Up?