Female Fertility and the Body Fat Connection by Rose E. Frisch, University of Chicago Press, 拢13/$20, ISBN 0226265455
鈥淵OU can never be too rich or too thin鈥� is a quip often attributed to the famously skinny Wallis Simpson. But Rose Frisch is not laughing. For years, she鈥檚 battled against both scientific prejudice and the fashion industry to make the case for female fat.
Frisch, now associate professor of population sciences emeritus at the Harvard School of Public Health, argues that women need a certain amount of body fat to maintain their fertility. Fall below that 鈥渃ritical fatness鈥� threshold through dieting and exercise, and ovulation ceases. You may be fashionably thin, but you鈥檙e infertile.
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In Female Fertility and the Body Fat Connection, Frisch lays out the evidence for her simple but powerful theory. It explains why well-endowed girls start to menstruate earlier than athletic beanpoles, and why female ballet dancers, bodybuilders or marathon runners often find they have become too lean to reproduce.
Adipose tissue, long written off as a passive energy store, is in fact a vital producer of growth factors and hormones, including oestrogen and the recently discovered leptin, which play complex roles in regulating both body weight and the reproductive system.
No wonder sculptures of ancient fertility goddesses depict lushly curvaceous females. 鈥淎 far cry from our current cult of pencil-slim women,鈥� snorts Frisch. Her clear, persuasive and accessible account describes her research, but this is also a self-help book designed to help women readers to determine the range of weight for 鈥渙ptimal health鈥�. You鈥檒l find detailed instructions on calculating your body mass index to see how much fat you鈥檙e carrying.
But it鈥檚 not all in favour of the larger lady. Too much fat and too little exercise can increase the risk of diabetes and various cancers, Frisch鈥檚 studies suggest. Her landmark epidemiological studies of university alumnae showed that women who had participated in organised athletic activity in college were far less likely to develop breast cancer and cancers of the reproductive system than their sedentary classmates. Leanness in the early years in particular may exert a powerful protective effect, she suspects.
Today Frisch鈥檚 insights are widely appreciated, but two decades ago, when she began her research, 鈥淚 had the entire field to myself鈥�, she remembers. She began work at the Harvard Center for Population Studies as a lowly research assistant. Now she has seen many of her ideas taken up by the mainstream.
One of her most intriguing theories is the suggestion that drinking large quantities of carbonated soft drinks 鈥� colas in particular 鈥� might weaken your bones. She and her colleagues stumbled upon a possible link when the nutritionist in the team, Jelia Witschi of the Harvard School of Public Health, thought to ask alumnae about their consumption of non-alcoholic fizzy drinks.
鈥淲e were very surprised to find that the former college athletes in each age group who currently drank non-alcoholic carbonated beverages were at higher risk of experiencing one or more bone fractures during their lifetime compared to former athletes who did not drink these beverages,鈥� reports Frisch.
The researchers struggled to find an explanation for their findings. Could it be that the phosphoric acid in the cola drinks was leaching calcium out of the bones? 鈥淪ome clinicians have reported an increase of bone fractures from occupational exposure to phosphorus, particularly phosphoric acid,鈥� Frisch explains. A small-scale study of adolescent boys and girls suggested a link between bone fractures and cola consumption among the athletic girls.
Although this has yet to be conclusively established, Frisch says, 鈥淥ur studies indicate that active girls and women should avoid a high consumption of cola drinks in the adolescent years and beyond to lower the risk of osteoporosis in later life鈥�. Frisch may have officially retired, but she鈥檚 clearly not lost her appetite for controversy.