We have all known someone with the ability to eat large amounts of calories, not even workout, and still look lean and defined year round.
By chance, these people have a revved up metabolism. What often happens to these people is they are lean when they are young, then at some point their metabolism slows down and they put on weight.
In fact, this was more often than not the case a couple generations ago.
The above picture was taken in the late 1940’s at Playland in Rye Beach, New York. Up until the late 1980’s, the majority of teens were lean without even trying.
All Young Adults Were Lean in My Dad’s Generation