Obesity: The latest spermicide

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Could obesity impact a man s fertility? To explore this possibility, a new meta-analysis, published in the Archives of Internal Medicine included nearly 10,000 men to determine whether obesity had any adverse affect on sperm count. Pooling data from 14 studies, researchers from the Ambroise Pare Hospital in France found some evidence that it does: Compared to normal weight men, men with a body mass index (BMI) of 30 or higher which is considered obese had a 42 percent increased risk of lower sperm counts (oligozoospermia) and a 81 percent higher risk of producing almost no sperm at all (azoospermia).

What are some possible mechanisms that could account for such an adverse relationship between excess adiposity and diminished (or absent) sperm counts? The authors outline a few: For instance, increases in fat tissue in the abdomen, hips, and scrotum could lead to an increase in scrotal temperature, which impairs sperm production. Alternatively, they suggest, fat tissue is a good repository for certain toxic chemicals. ACSH s Dr. Gilbert Ross, however, finds no scientific plausibility to the latter explanation. There is absolutely no credible evidence that toxins stored in fat contribute to reductions in either sperm counts or fertility.

ACSH s Dr. Elizabeth Whelan has another bone to pick with the current study results. The authors state that rises in global obesity rates are correlated with decreases in male fertility, but as she points out, several credible studies have determined that reduced sperm quality is a myth. On a population basis, sperm counts are not actually declining, she adds, but it s clear that obesity is increasing. So although the authors can conclude that excess body fat affects sperm production, they cannot associate obesity with decreases in male fertility.

ACSH s Dr. Ruth Kava agrees, and notes that it s impressive how many body systems are negatively affected by obesity (as we described in our book, Obesity and Its Health Effects). Indeed, a number of changes to human physiology and health that are erroneously attributed to so-called toxic chemicals, are really effects of our on-going obesity epidemic."