What controls our appetite?
It is not a lack of character; feelings of satiety are only a break in the constant hunger we are gifted with. Perhaps, it has historically been about pure survival - we have to eat to survive.
Many people with anorexia eventually die of metabolic collapse and starvation while others commit suicide, which is far more common among anorexics than women with other mental disorders. So far, the disease has been considered a mental illness primarily, but new findings mean that it may be re-examined.
Today, there is a higher risk that we eat to death than we starve to death. However, it doesn’t take into account the body’s hunger signals. What then happens in the body when the stomach starts to cure and the craving sets in? What can help us eat just as much as we actually need?
The appetite control is mostly controlled from the brain, more specifically from the hypothalamus which receives input from the gastrointestinal tract, adipose tissue and from the liver.
There are different hypotheses about what controls appetite
Lipostatic theory: increased fat tissue decreases appetite and decreased fat tissue increases appetite. Despite the epidemic of being overweight, there are many people who are at the same weight year in and year out without seeming to care about what they eat and drink. They sense this effect and unconsciously regulate their energy intake.
Glycostatic theory: high blood sugar lowers appetite and low blood sugar increases appetite. We have probably all known this, at low blood sugar the body screams for energy.
Increased feeling of satiety
Thermostatic theory: lowered body temperature increases appetite, and high body temperature decreases appetite. When it’s 30 degrees hot, we often eat a little lighter food, we don’t have the same appetite. To be measured on a smaller amount of food and drink hot, it gives an increased feeling of saturation.
When exercising and other physical activity, our energy needs increase, and so does our appetite, which is quite logical. Unfortunately, even when we are entirely inactive, appetite increases, so we need physical activity for appetite regulation to work.
Hunger is a stress for the body, at the same time stress is one of the factors that releases hunger signals. Fast, low blood sugar and an increased energy demand trigger these signals. The hunger signals keep you awake and increase your appetite. They decrease on “luxury metabolism”, so they make sure that the body does not waste more energy than it has to, body temperature drops, for example. They increase fat storage and the necessary energy consumption decreases.
Stimulates the bowel motor
Orexin is a hormone that is released that contributes to increased alertness. So it is not suitable for the night’s sleep to go to bed hungry. Those who suffer from the disease narcolepsy or “sleep sickness” have no orexin in the body. The hormone ghrelin is one of the few hunger signals that come not from the brain but the stomach. It prepares the body for food intake by increasing acid production, stimulating the pancreas and intestinal motor.
The strongest hunger signal
Neuropeptide-γ is the most active and strongest hunger signal. NPY is the biggest culprit when it comes to making us overweight. It increases the appetite specifically for sweet and constantly pushes the body towards a positive energy balance, more energy into the body than we do with it. NPY is activated by high blood fats.
Dopamine is released when you eat sweets and soft drinks. Dopamine gives you pleasure feelings, and endorphins make you feel good while the hormone ghrelin creates increased sweetness and hunger. That is why you like to eat more sweets than what is convenient when you have once started chewing sweets.
The ability to feel hunger can never be knocked out, but the ability to experience satiety can. Saturation is, as I said before, just a break in our constant hunger. Being measured means prosperous. Feel good the hormone serotonin is released, and a calm feeling emerges.
The saturation signals affect our reward system, make us happy and the motivation to eat drops. It increases our “luxury metabolism”, the body temperature increases and the necessary energy consumption increases. The saturation signals come mainly from the stomach, intestines and adipose tissue.
The saturation peptide CCK, cholecystokinin is released by fat and protein and inhibits gastric emptying. This is one reason why protein and high-fat foods are saturating longer.
CCK inhibits the release of NPY, our primary hunger signal. CCK increases our serotonin content which gives us satisfaction and CCK reduces the release of dopamine.
From the intestine, enterorotatin is released, which is an enzyme that breaks down fat. It also reduces dopamine and increases the release of serotonin. It is catabolic and increases our luxury metabolism.
The most dangerous fat
Leptin is produced in the fatty tissue and inhibits the hunger signals and increases basal metabolism. This means that the more fat on the body, the less hungry, right? Unfortunately, there is a feedback mechanism that causes leptin to inhibit its production, and a leptin resistance occurs. The most dangerous fat on the body, the abdominal fat, also produces only half as much leptin. Our history as cave people in constant hunting for food for our survival is continuously a burden to us.
What, then, can we do to maintain a healthy weight without having to be more or less always hungry?
Since fat and protein stay longer in the stomach and saturate for a longer time, should we indiscriminately eat a fatty and protein-rich diet?
If we base our food on saturated fat and red meat, we may stay saturated, but we run the risk of having other less positive effects. Saturated fat is more easily stored in the fat tissue as it is very stable, and the type of fat that the body likes to save for later use while monounsaturated fat is easier to burn. Polyunsaturated fat is the most sensitive to oxidation, which means that the body primarily uses it as fuel to avoid radical formation.
An excessively high intake of saturated fat can cause, among other things:
- Type 2 diabetes
- Some cancers
Possibly an increased risk of cardiovascular disease
Eat fat but avoid the saturated fat. Choose monounsaturated and polyunsaturated fats we find these fats mainly in vegetables and fish. Protein saturates the best of all nutrients. A high protein diet means eating less without getting hungry fast again. Protein balances blood sugar which also leads to a more controlled appetite. Protein contains nitrogen which increases energy consumption as it must be excreted through the urine. Together with the saturation effect, makes an increased protein intake a good trick for keeping the weight off. Choose fish, eggs, milk and vegetable protein sources in the first place. Red meat and meat products contain a high proportion of the fats we should avoid, then meat from a game is a better alternative.
Carbohydrates are the body’s primary fuel, eat them but choose them with care. Avoid refined carbohydrates that quickly go through the system that really only raises blood sugar for a short while and then leaves us even more sweet and hungry. Eat high in fibre, fibre saturates and keeps stomach and intestines busy.
Eat and drink hot. The heat signals saturation. Exercise to keep energy consumption going. In this way, we ensure that the energy balance is maintained and we keep the weight without being hungry.