Recently joined a new gym and they asked if I wanted to look at my metabolic age. I'm 55 and it said it was 70!!! I'm 5ft 3, weigh 11st (30J boobs don't help!) Size 12/14 and walk 3 times a day over 10k steps. I know I need to up my fitness but that was a shock! Conversely my friend of the same age, 2 stone heavier and off work for 12mths recovering from a brain op had hers checjed at 62. What does it use for calculations?