This is an interesting study that follows on the recent discussion of the “40% average body fat” post.
Biology is all about “sweet spots” and ranges, like Goldilocks and her porridge, neither too hot nor too cold. I have always maintained that fitness/activity and good nutrition is more important than a particular % of body fat in determining overall health and function… up to a point.
Past that point, the chemical and mechanical contribution of adipose tissue begins to increase the risk of chronic disease, loss of function, and morbidity.
That exact point is unique for each woman and depends a lot on individual risk factors, especially fat deposition patterns and other known risk factors such as medication use, smoking, and family history.
But the point remains: as organisms, we function best — and optimally — within a certain range of physiological states: body temperatures, pH, etc. and this includes % of adipose tissue. (Luckily body fat % can be a relatively wider range than, say, calcium regulation or temperature. A 10% variation in your temperature would probably spell death.)
I mentioned heavyweight football players as examples of folks who are very fit, but risk experiencing health difficulties nevertheless.
A recent study explores this. Here’s the abstract; you can read the full study here. What is especially notable is that by all other measures, these guys should be healthy as horses: they’re well-conditioned young bodies genetically suited to physical activity, who do all the types of athletic training that we know optimizes health and insulin sensitivity — weight training, interval-type cardio, etc. Despite all that, the proportion of body weight raises their risk.
Of course, one un-named confounding element is the use of androgens and other anabolics. We know that androgen use does increase cardiovascular risk profile. On the other hand, everyone else on the team is probably also “supplementing”, so this probably isn’t as significant as it might be with, say, a bodybuilder/non-bodybuilder population comparison.
Borchers, James et al. Metabolic Syndrome and Insulin Resistance in Division 1 Collegiate Football Players. Medicine & Science in Sports & Exercise 41 no.12 (December 2009): 2105-2110.
Purpose: To estimate the prevalence of metabolic syndrome and insulin resistance in a cohort of Division 1 collegiate football players.
Methods: Ninety football players were evaluated in a cross-sectional study to estimate the prevalence of metabolic syndrome, insulin resistance, and associated risk factors. Obesity was defined as a body fat ≥25% determined by BOD POD measurements. The National Cholesterol Education Program Adult Treatment Panel III criteria were used to estimate prevalence of metabolic syndrome. Quantitative insulin sensitivity check index calculations were performed to estimate prevalence of insulin resistance. Linear regression techniques were used to determine association between body fat percentage and other measured continuous parameters. Fisher exact test was used to determine association between nominal variables, and one-way ANOVA compared the three groups defined by position.
Results: Summary measures showed a small prevalence of abnormal individual measurements. There was an association between body fat percentage and most evaluated parameters (P < 0.05). The prevalence of obesity, insulin resistance, and metabolic syndrome was 21%, 21%, and 9%, respectively. Obesity is closely associated with metabolic syndrome (P < 0.0001) and insulin resistance (P < 0.0001) in this population. All subjects with metabolic syndrome were obese, and the odds for insulin resistance in the obese group are 10.6 times the odds for the nonobese group. Linemen (n = 29) had 19 of the 19 obese subjects, 13 of the 19 subjects with insulin resistance, and all subjects with metabolic syndrome.
Conclusions: There is a strong association between obesity and both metabolic syndrome and insulin resistance in Division 1 collegiate football players. Linemen are at significant risk for metabolic syndrome and insulin resistance compared with other positions. This may be predictive of future health problems in Division 1 collegiate football players, especially linemen.