...Sustainable weight loss doesn't mean loosing weight forever...It simply means not gaining back all the extra weight which you lost, sustainable weight loss means being able to keep you bodyweight or BMI at a healthy level indefinitely and not having to worry about gaining all those extra pounds of fat back...Sustainable weight loss is the same as successful weight loss....There are a lot of people out there who loose weight through special dieting, only to gain it back few months down the road.