A lot of healthy looking people arent always so healthy. I contribute that largely to two different aspects.
First is drug abuse and second is nutrition.
Some people look to drugs to get cut, add mass and what have you and ignore the fact the body needs nutrients to fuel growth and proper function. Athletic people put higher demands on their body, they do more damage and need better nutrition to remain optimal. What usually happens though is the nutrition part is ignored and drugs are used to force changes which in many cases actually exacerbates mild deficiencies because it forces the body to use resources in ways it may otherwise not.
I honestly never paid much attention to nutrition in a bottle, used to think clean eating would do the trick but now in middle age and with a lot more study and research under my belt I have a much greater understanding of the huge role nutrition plays in our health AND why more often than not we simply can not get the nutrition we need from food alone.