Everyone is different. Typically, losing 2-3 lbs a week is considered the max for a safe rate of weight loss. Some people lose more, but many times it's water, etc. Everyone has a different metabolism and rate of loss. Not everyone is willing to put in the same effort to get results. Some weeks you lose, some you don't. There is no real average... but rapid weight loss over a period of time typically is the kind that comes back very quickly if you aren't careful. Most doctors give a lower number because they understand the obsession with weight loss in this country and don't want to contribute to the dangerous ways we all deal with losing weight.