[Perfectlap]

^I'm not sure if metabolism slows due to age. I think it's more the effects of 'getting old' as in not staying active and lettting muscle mass shrink away in favor of sitting on the couch. I used to cycle in a park where this one rider was a regular. He was ripped like Lance Armstrong during the last week of the Tour. The first time I came up on him I noticed that while he was keeping a good pace he wasn't really cranking it. His dyed black hair threw me off because when I looked over to say I hi I realized this was a guy was easily 70 years old. He later told me he was like 72 or something and ate a can of corn every day.
Once the average American hits 35 he sets himself up for the double whammy, weight goes up (more money to eat bigger) and his activity goes down. The metabolism also gets bombarded with more stress, less sleep, more sugar, more acohol, more refined flour carbs, more animal/cheese fat vs the good mono unsaturated fats or in some cases ALL OF THE ABOVE! I think the average human on Earth today can live much longer and healthier than was ever possible but we seem to be be going in the other direction.