In this historical period, Australia is experiencing a dark period regarding the relationship with weight. More and more Australians are overweight or obese, with serious consequences on public health. According to recent studies, weighing too much would have negative implications for fertility too.
The regulation of the menstrual cycle is linked to a delicate hormonal balance. Both the excess weight and the deficit can affect it. Specifically, overweight and obese women have high levels of the hormone leptin. This can undermine hormonal balance and reduce fertility. Furthermore, excess fat mass is linked to increased insulin resistance. To regulate blood sugar levels, the body must therefore produce more insulin and lower levels of sex hormones.
One study examined the probabilities of conceiving within a year in normal and obese women. In normal-weight women, the odds are 81.4%. In those obese, however, they are 66.4%. A very marked difference, linked to the factors mentioned above. In severe cases, obesity affects the hormonal balance so much that it blocks the release of the oocytes. The phenomenon is 3 times more likely in women with a body mass index above 27, therefore overweight.
However, many overweight women continue to ovulate, but this does not mean that their fertility is intact. According to the data, each unit above the BMI 29 (obesity threshold) lowers the odds of conceiving by about 4%. A woman with BMI 35 (severe obesity), therefore, has 43% less chance to conceive than a normal-weight woman.
Obesity and overweight also have serious consequences on male fertility. Excess weight is in fact linked to hormonal problems and a greater risk of erectile dysfunction. According to studies, 10 kg too much is needed to reduce male fertility by 10%. In addition, too much fat mass reduces the quality and quantity of sperm.
The data are discomforting, but they also offer a solution. These problems are not permanent. Losing weight increases your chances of conceiving. In obese women, a loss of 5-10 kg is enough to increase the chances of a pregnancy. Losing 7% of body weight and doing at least 150 minutes of physical activity per week improves health and makes you more fertile.