Macroelements are a lot like hunger, however it is divided into three groups, carbs, fats, and protein. Fats and protein decrease at roughly the same speed, however. They decrease the slowest, roughly 100 minutes until you are out. Carbs decrease faster, roughly 75 minutes until you are out.
Macroelements (and hydration) affects your max health. each gives 25% of max health hence all of them gives 100% max health. only if you run out of all macroelements and hydration will kill you (you reach 0 HP).
The lesser your current macroelements, the faster stamina depletion.
The list of effects is here