First of all yes age has to do with it. Your metabolism slows as you get older. Second to have been on one diet for 7 years is not good at all. Your body has become accustomed to it. Additionally I've heard that those diets can cause gout which believe me if you haven't gotten it yet you do not want it. I've also heard of kidney damage being done by that particular diet. The problem with Atkins, South Beach, etc etc etc are they are just that DIETS they are NOT meant to be a long term solution. You need a lifestyle change not a diet. Let me suggest Weight Watchers. They teach you to eat and change your lifestyle bad habits of eating. They are a long term solution. Please though before you do anything, if it's been over a year or two since you've had a complete physical GET ONE and be honest with your dr. that you've been on this 'diet' for 7 years.