Post-ingestive feedback is a term coined by Fred Provenza, who conducted several experiments on nutrition throughout the late 20th century and probably this century too, idk. I'm just going to tell you about one though.
Essentially, through previous experiments, the idea was postulated that animals/humans base their dietary preferences on what they need the most. To test this, Provenza made some sheep deficient in phosphorous. The idea was that they would prefer food based on the phosphorous content due to their lack of phosphorous.
He gave them both coconut and maple flavored feed, which did not contain phosphorous. The sheep didn't care for it much, and did not really seem to prefer either one.
The next step was to pump a phosphorous solution into the stomach of the sheep directly after feeding. This eliminated the variable of them preferring food which actually contained phosphorous, and created a scenario in which their association with phosphorous was with the smell/taste of the food itself, and not an association with the actual taste of phosphorous.
The sheep who pumped after being fed coconut feed, preferred the coconut feed. Those that were pumped after eating maple feed, tended to prefer the maple feed. They were associating the smell and taste of coconut or maple with a food that was rich in phosphorous.
Eventually the sheep were no longer deficient, and they went back to having no preference.
He tried this experiment with calicum and protein, and the results were the same. The sheep preferred whatever flavor of food they associated with actual nutritional value.
Similar experiments have been conducted on humans, and have turned out the same. We base our preferences off of foods that have nutritional value. Now this doesn't mean "healthy food" it simply means stuff that has what our body needs. If you are deficient in vitamin C and you have already associated oranges with receiving an influx of vitamin C, you will crave oranges, and so on and so forth.
The problem for humans lie in the inability of our bodies to know when to stop eating certain things. Mainly, fats and sugars, which were such a rarity for pre-civilization humans that we crave it uncontrollably. Back then, we were used to eating to survive. All that extra energy, and all those calories, was incredibly beneficial to stock up on.
This obviously hasn't translated well into the 21st century, and now we are dealing with obesity because our post-ingestive feedback is based on unhealthy things. Our bodies want to stock up on carbs when we are not deficient, and food manufacturers know exactly what chemical triggers to fire off in order to tap into those cravings. Almost everything nowadays is flavored. Even the raw, "natural" meat in the stores has this flavoring. All the "natural" in "natural flavoring" means is that it originated from a natural source. It does not actually mean that this substance was found and extracted in nature.
Understanding this link is really important, because it helps you to better understand the patterns and reasons that you crave certain foods. Your body is telling you that you need to eat another jelly donut, but you don't really need it. It's an active battle, and in order to win this battle, you need to train your body into craving foods that are actually good for you. If you eat an apple every time you crave sugar, you will soon begin to crave apples instead of sugar frosted donuts, or other carbs.
I'm not saying that you shouldn't eat these things, I'm just saying that we shouldn't be eating as much as our body tells us to. Fat people can really get stuck in a loop on this one because their bodies are so accustomed to eating very high fat/sugar diets that it's a hell of a cycle to break. They crave these foods so much more than people who are not fat, because their brains have made the association that these are the foods to go to when they are in need of fat/sugar, and like I said earlier, humans are ALWAYS "in need" of fat and sugar.
I've been eating considerably less sugar and carbs for like the past year+, and I can say that a lot of the cravings really do go away. It used to be such a struggle for me to eat healthy. I was never overweight (probably should've been) but I would still feel like shit from eating too much sugar, or too many carbs. I still take lots of fats everyday (dat DHA and EPA) but they're the right kind of fats, and not the oily nastiness that you'll find in a frozen strip of Tyson breaded chicken tenders, or in a carton of McDonald's french fries.
I want to switch to eating sardines or something for my daily fat value, but I don't know if I can stomach them.
Anyway, /thread.