So, what determines satiety and hunger? It could be:
- the capacity of our stomach,
- the taste of the food we are eating,
- the energy available in our body at a given time.
It is interesting to observe animals, as their eating habits are not guided by learned patterns and discipline, like human beings. They simply eat when they need and they seem to choose the food items packed with the necessary nutrients. (Curt Richter was one of the leading authorities in discovering that eating behavior is influenced by hormones.) A few examples:
- Rats without adrenal glands are unable to retain salt. When they are fed their usual diet, they die within days due to salt depletion. When they are given the option of salty food, they - by instinct - will choose to eat more of the salty food rather than their natural diet. This way, they can live as long as the other healthy rats.
- The same type of experiment has been conducted on rats whose parathyroid glands were severed. This condition leads to calcium deficiency. When these rats were given the choice to consume calcium lactate, they could stay alive by choosing to drink from the calcium lactate rather than pure water.
- Or for instance, after pancreatic damage was induced in laboratory animals (rendering them diabetic), they choose to eat from the fat and protein rich food instead of the carbohydrates. Somehow, they knew by instinct that they were unable to use carbohydrates as fuel.
Jacques Le Magnen discovered that: "Hunger appears and disappears according to normally occurring fluctuations in the availability of utilizable metabolic fuels, regardless of which fuels they are and how full the storage reserves."
This means that no matter how much storage we have in our fat tissues. If that fuel is blocked (by insulin) then we feel hungry and want to rest in front of the TV. The stored energy is not available for usage.
"When Le Magnen infused insulin into sleeping rats, they immediately woke and began eating, and they continued eating as long as the insulin infusion continued. When during their waking hours he infused adrenaline - a hormone that promotes the mobilization of fatty acids from the fat tissue - they stopped eating.
"If this hypothesis holds true for humans, it means we gain weight because our insulin remains elevated for longer than nature or evolution intended, and so we fail to balance the inevitable fat deposition with sufficient fat oxidation. Our periods of satiety are shortened, and we are driven to eat more often than we should."
- Gary Taubes
So, on a high carbohydrate diet, we tend to eat frequently and overeat as high insulin levels render the energy unavailable for our body to use. Our hunger is stopped once our stomach stretches. On a high fat diet, satiety is reached very quickly - as the fatty acids (energy) is not blocked by insulin. We reach satiety without expanding our stomach to extreme levels.