Leptin is a hormone that comes from your stored body fat. It controls your metabolism, including the function of thyroid hormone. It controls your body weight. Women have a higher percentage of body fat than men, and thus higher levels of leptin even when not pregnant. This is specifically so that women have enough energy reserves to sustain pregnancy and nurse their child. In fact, if your percentage of body fat is too low you may have a lot of trouble getting pregnant in the first place.

During pregnancy leptin levels naturally rise, enabling more weight to be stored to support these vital energy reserves. Under the influence of ...