HCG, or Human Chorionic Gonadotropin, is a hormone produced during pregnancy by the placenta after implantation, and doctors sometimes prescribe it for fertility issues. But this hormone has also gained popularity as a weight-loss supplement — and using it as such can be dangerous. In fact, the U.S. Food and Drug Administration (FDA) warns against purchasing over-the-counter hCG, as these supplement products are illegal. (34)
As such, we rely on hormones to precisely and tightly regulate body fat. We don’t consciously control our body weight any more than we control our heart rates or our body temperatures. These are automatically regulated, and so is our weight. Hormones tell us we are hungry (ghrelin). Hormones tell us we are full (peptide YY, cholecystokinin). Hormones increase energy expenditure (adrenalin). Hormones shut down energy expenditure (thyroid hormone). Obesity is a hormonal dysregulation of fat accumulation. We get fat because we’ve given our body the hormonal signal to gain body fat. And those hormonal signals go up or down according to our diet.
Everyone is different. How quickly you burn calories when you are not physically active can be very different from other people based on your specific genes, biology, and past. While scientists know that there are 3,500 calories in one pound, simply eating 500 fewer calories every day for a week (or 3,500 fewer calories in a week) does not always end in losing exactly one pound.