The world health organization (who) estimates that about percent of all food is lost to food spoilage.

The World Health Organization estimates that about 20 percent of all food is lost to food spoilage. Some of the biological, chemical and physical changes that lead to spoilage are preventable by some preservation methods. Spoilage is characterized by a decline in eating quality, resulting in food that is less acceptable to the consumer in appearance, taste, texture or odor. The foods we eat are all derived from living matter making them subject to the natural process of decomposition. Food not only decomposes but it also lost or spoiled by being consumed by creatures other than humans which are rats, mice, flies and microorganisms. 

Atp is is our little "pocket" of energy. of course, if you have too little, then it means you have too little energy, and you'll pass out. the way to not have enough, is to have no energy sources (glucose, fats, proteins). you can't have too many atp molecules. cycles like the krebs cycle produce it, but if you have too much of any substrate (or too little for that matter), the cycle stops and atp is no longer made (it stops until substrate levels are such that the process can go on). in any case, this is unlikely since atp is constantly hydrolyzed and remade, even while you're asleep. you won't have too much. if you have zero, you are dead or dying.

Because the carnivores keep the herbivore population in check