Shouldn’t your body just give you the stop signal and make you not overeat? Then why do people get fat at all?
In: Biology
In addition to the other answers, when you want to satisfy your hunger, the calorie value of your food is a big factor. (Satiation doesn’t care about calories)
For instance, you can eat 2 pounds of broccoli and be really full but not take on too much calories, or you can eat 2 pounds of bacon/donuts and consume several thousand calories in one sitting.
Satisfying hunger with the wrong foods (calorie dense) can really spike up weight if you are already meeting your calorie needs.
Physical hunger, like being famished with a headache, is different than psychological hunger, like smelling cheeseburgers and being down to eat one, even though you are not hungry.
New research is showing a big factor in obesity is leptin resistance. Leptin is a hormone released by the body to not only trigger the feeling of being satiated and full, but also signals to the body that it’s had enough food. When your mind isn’t getting the signal that it’s full, you keep eating or eat more often. When your body doesn’t get the signal it’s had enough food, it stores most all calories it takes in because it feels like it may be in starvation mode.
Edit to add there is research that found a few specific genetic mutations that likely contribute to leptin resistance, these mutations can be both inherited or spontaneous.
Don’t forget the intestinal microbiota exists and interacts directly with the vagus nerve.
From National Library of Medicine: ***”Microbiota-gut-brain axis: relationships among the vagus nerve, gut microbiota, obesity, and diabetes”***
“Because of its enteroendocrine cell-mediated interaction with the gut microbiota, the vagus nerve may provide a potential pathway through which **gut microorganisms influence host feeding behavior and metabolic control of physiological and pathological conditions**.”
I find it fascinating.
To add in, they’re finding that there are a lot of people who have disregulation in their metabolic processes. Most notably, the pancreas produces too much insulin after eating, causing blood sugar to plummet and causing cravings after eating. Over a lifetime, this can turn into insulin resistance, or type II diabetes.
Basic gist is there’s a difference between “sated” and “full”. In the former case, we feel we’ve had enough to eat and don’t desire to continue eating. The latter case is when our stomachs are physically full. Our stomachs stretch quite a bit, and can hold far more food than we need to be sated. But a large number of obese people don’t feel sated because of the metabolic disregulation.
Many things can mess up the hormonal feedback loop that is supposed to tell you to stop eating. For one thing, at least one trigger is based on volume, not calories. The actual stretching of your stomach as it fills. But things that in the bariatric surgery world are called “slider foods” don’t ever stretch the stomach enough to trigger that. This includes liquid calories like soda, sweet/fatty coffee drinks, ice cream, etc that “slide” right through as well as things that crunch up to much smaller sizes but are still high calorie – think potato chips. If you crush a full bag of potato chips it won’t take up much room at all, but still has all the calories of multiple servings. When we chew, we are crushing it up, so we can fit a CRAP TON of chips or crackers in our stomach without it ever getting full to the point of stretching. Dense proteins do not crush down as much, and stay in the stomach longer, so more likely to trigger the “full” feeling and tell the brain we are done eating. It’s why you feel so full after a steak dinner, and not after a bag of chips. We didn’t evolve to have easy calories that don’t stretch/fill the stomach.
Another issue is that things like stress and lack of proper sleep can mess with the hormones that trigger fullness. And most of us do not get enough sleep.
Also, many people have insulin resistance. Insulin it what gets the energy from the food you eat into the cells where it can be used. If your cells are not letting insulin in with that energy, your cells are starved, which triggers you to want to eat more to get energy to the cells. It’s a feedback loop gone haywire, and all that energy that isn’t getting into the cells gets stored as fat. So yo are eating and eating, but your actually cells are still starving. Sucks.
There are also issues related to epigenetics – what and how much food your mother ate while pregnant with you, and even what and how much food your GRANDMOTHER ate while pregnat with your mother will influence the expression of certain genes – some of which are linked to obesity.
modern food literally being engineered to be addictive while tricking the body into thinking its still hungry, as well as poor nutrition, and poor coping mechanisms.
you feel bad, you eat, you still feel hungry, look down, feel ashamed to go outside, you eat, you watch tv, it tells you to eat, you eat, you don’t notice how full your are cause your youtube/tiktok feed is too good, you eat. it can be a vicious cycle, especially if you dont have people around you who care enough to worry about you, or maybe you do, but youre too depressed and dependent on sugar to notice.
Because it’s actually not that hard to ignore the signals to a certain point. There’s a decent amount of physical space left in your stomach when the “full” signals start. You can ignore them for probably another helpings worth before you *must* puke because there’s no space. There’s a gap between the “I’m full” signals your body sends and the literal volume of your stomach cannot hold anymore. Seriously obese people regularly ignore the signals and eat til they’re gonna puke. They ignore their signals for so long they don’t even notice the signals anymore. Plus the more you eat, the bigger your stomach stretches, so the more calories you can fit per meal increases too. But your caloric output doesn’t change.
And that’s assuming, of course, that there isn’t a glitch somewhere. Because human bodies are also pretty well known for all our glitches too. Sometimes a person’s signals just don’t work properly, or something else along our very wonky system isn’t working. It happens pretty often.
Because in 1978 the food guidelines changed. Since then, obesity is though the roof, as is diabetes. They demonized fat, and found a sugar ally.
I was just reading research last night about the GLP-1 agonist drugs (Wegovy, Zepbound). Scientists originally thought the mechanism was simple: release more of the hormone in the gut and the body would respond.
Instead, scientists are learning the reaction actually happens in the brain. The brain gets used to a certain level of these chemicals. Just like with diabetes, tolerance can build up. Once the rubber band is stretched, it’s very difficult to get it to go back to the original setting. We diet, we stretch it more, we give even a little on calories and food craving go way up. These newer drugs quiet that craving.
One incredibly interesting side observation is that craving for other substances (alcohol, drugs) or addictive behaviors can also decrease.
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