I have not read the entire thread, but I think I have most of the highlights.
On a personal note, I believe that Racoon is correct, but as to why we consume so many more calories then we burn off is not always due to laziness.
We are driven by hunger to eat (usually). Hunger is indirectly controlled by our blood sugar levels.
As we consume food it is converted by our bodies into usable forms of energy. This available energy signals the body to produce insulin which in tern forces the muscles and fat cells to store energy. As the glucose levels drop the insulin production decreases and blood insulin levels drop a short while later. Insulin is the great mediator of the bodies energy system as is used by a large number of systems.
The important difference today is that the majority of the food that we eat in first world countries could almost be considered pre-digested. The foods we consume are very rapidly converted into blood glucose. As the rate is much higher then we were (generally speaking) genetically prepared for, our system has some difficulties coping. The rapid increase of blood glucose encourages larger then normal insulin production in our body as it tries to normalize glucose levels.
High insulin and glucose levels are exactly the conditions that muscle and fat cells need in order to maximize energy storage. Muscle cells have limited energy storage in the form or glycogen, but fat cells can store significantly larger amounts of energy.
The processed foods we eat these days are converted so rapidly that they are rather quickly consumed, leaving our bodies in a particular state. As the source of energy is depleted, the body, with its high levels of insulin, quickly stores the remaining glucose as fat. The result is a drop to a low blood sugar state that will continue until the insulin is degraded by the liver. It can take the body up to an hour to degrade the insulin that it has produced.
This low blood sugar level is offset somewhat by the liver as it creates glucose from its stores, and the fat cells do start to shed their stored energy as well. Another side effect of this is drastically increased hunger as the body sees the low blood sugar as a need for more energy.
A rather vicious cycle
The short of it:
- We get hungry due to low blood sugar
- Modern food we eat rapidly turned into sugars
- Insulin levels match sugar levels fairly rapidly.
- Body stores energy and fat
- Modern food rapidly depleted
- Sugar levels drop, but Insulin levels take time to normalize
- Sugar levels forced below healthy levels by high Insulin levels.
- Body gives off some fat and glucose stores to equalize blood glucose levels
- See step 1
I think the solution is to eat foods that have a high glycemic index.
Please keep in mind that my opinion is not based on scientific studies that I can point to, but rather is intuited from a more general set sources and experiences. As with many intuited solutions, the body often confounds us with counterintuitive realities, and I would be very interested in learning more on this.
Edit: one thing I forgot. The liver gives up its stored energy quickly to match short term energy needs, while fat cells give up stored fat slowly to meet long term energy needs.
, it is defenitely time to go home.
