What are the effects of not eating on your body?

Answer 1

The effects of starvation are somewhat complicated, as your body is constantly managing its reserves of a whole bunch of different energy sources, which are all used by different organs at different rates. But I will try to generalize...


The first thing your body will run out of is glucose. Glucose (aka blood sugar) is the energy your body needs to use for everything. It is created by the digestive process. When your blood sugar levels are low, you feel tired and may have a harder time thinking. Blood sugar levels start to fall within a few hours of your stomach being empty.

Every chemical reaction in your body requires protein as a catalyst, and your body has no way to store protein except in the form of muscle. Thus, your muscles are one of the first things to go when you start starving. Your body needs protein at least every 6 hours to avoid your muscles being catabolized to keep it alive. Don't worry because this loss will be small at first.

After your body has been eating your muscles for a while, the next thing it runs out of is glycogen. Glycogen is the stored form of glucose, and is stored mostly in the liver and muscles (note glycogen is stored IN your muscles, your muscles are not made out of glycogen).


Now, during this whole time, your body has been slowly burning fat on the side. Fat is your body's reserves, and the process of turning fat back into energy is slow and inefficient, so it prefers the other methods whenever it can. Now that everything else is depleted, you would like to think that your body would start to really tear into that fat, right? Unfortunately, your body is now running on E and is setting in for the long haul, trying to keep you alive as long as possible. Instead of going into overdrive on the fat consumption, it instead starts to lower your metabolism to allow you to last longer with what you have. A lower metabolism means your body is spending less energy keeping you how you are, which means it starts to lose both fat and muscle. However, muscle requires a lot more energy to upkeep than fat does, so it gets lost the fastest. This decrease in muscle mass further drives your metabolism down, further lowering your body's energy requirements, and basically turning itself into a slowly deflating balloon of fat.


And that's just as far as energy sources go. Suffice to say, lack of food will also wreak havok on the rest of your natural processes, such as your immune and hormonal systems.