We spoke with a pair of cousins, one an Army veteran, the other a current member of the Navy, about some of the toughest situations they've found themselves in. Army basic training, according to Mates, is all about discipline. It's about knowing your role and not stepping out of line. And if you do, well, you pay a price. Mates said, In basic training, they call it 'getting smoked.' Push-Ups until you puke. I was always getting smoked.
Caffine is the most popular and probably the most studied of all drugs, and serious adverse effects in real life have resisted demonstration. There are pop claims about caffeine interfering with absorption of iron and vitamin d; if there were any real effect on real human beings, it would be obvious by now.
The caffeine in coffee is a strong diuretic in the human body. In large doses it can increase fluid flushing through the kidneys which leads to a frequent need to pee, loss of minerals and other important nutrients and dehydration. Dehydration may actually lead to weight gain in a roundabout way.