A 12 pack of what? Cans, bottles what? 6 cans is equal to 9 servings in a day. That is getting to be too much. If it is 6 bottles then it deffinately is. That is deffinately too much.

He must not eat much at all becuase I simply cannot believe that he can drink that much soda a day and not way at least 100 pounds more than he does. High metabolism or not that simply is a whole lot.

Now lets start with the cafeine content. Pepsi has 25 mg of caffeine per serving and coke has 35 mg per serving. A recent study showed that health problems starting arrising from those that consumed 300 mg of caffeine a day. Caffeine also takes more water to process than caffeinated drinks provide so it has a dehydrating effect. This can result in headaches, muscle aches, skin and organ problems, lack of energy and not being very clear minded. Excess caffeine also affects kidneys, heart and more.

All of that sugar can possibly cause diabetes but it seems unlikely if that person is not overweight. Unless a person has diabetes naturally it normally develops from being overweight, but not always.

As long as he is not gaining weight and does not have problems associated with excess sugar and caffeine then there is not much to be concerned about. But I find it hard to believe that he does not have some sort of problems from long term use of too much caffeine.