Got a sweet tooth? Blame your liver
exactlyscience.com
exactlyscience.com
This is a pet theory of mine. That, vastly simplifying, our bodies try to make us eat until we have a sufficient amount of whatever number of elements they need to function. The more varied you eat, the less you need to eat, conversely, the more homogeneous your sources of food (bread, rice...), the more you'll need to eat to try to get what is hardly there.
I have no idea whether this idea is mainstream between researchers but it always seemed to me as feasible as a satiety mechanism as just counting calories, and it explained quite well the observations I've made about myself. Anybody here could point to the current state of the art in the field ?
This is a really interesting idea, but I think equally valid is the notion that a hunter gatherer really is only seeking out short term gain. I think people are very drawn towards immediate, stark energy, which is why sugar and simple carbs are such an epidemic. Overeating seems like a byproduct of avoiding scarcity.
I definitely believe that people crave certain things given certain nutritional deficiencies, though.
* Your stomach contains a functional brain with ~25% of the neurons of the one in your head * Gut microbiomes have widespread impact on physical and mental health
We need ~20 amino acids and some micro-nutrients to meet our nutrition needs (to our current knowledge). The microbiome adapts to break down different food sources into these nutrients and the body will adapt if it lacks certain nutrients but functionally wont work as well.
The idea that there's a signaling mechanism between all of these systems to encourage the right type of consumption is rationally sound.
"The enteric nervous system in humans consists of some 500 million neurons[6] (including the various types of Dogiel cells),[1][7] one two-hundredth of the number of neurons in the brain, five times as many as the one hundred million neurons in the human spinal cord,[8] and about 2/3 as many as in the whole nervous system of a cat."[1]
I'm on board with this pet theory too. For example, we know that the micronutrient Chromium is required in the range of 50 - 200 micrograms per day, and that it is essential for sugar and fat metabolism and that most people ingest less than 60% of the minimum recommended (less than 50mcg) per day.[2]
It makes sense to me that the body would induce hunger in an effort to take in enough food to meet a micronutrient deficiency > that this mechanism is derailed by the SAD (Standard Affluent Diet) > a negative feedback loop is induced.
The fasting method I'm employing: 3 24-hr fasts a week (from dinner to dinner Sun, Tue and Thu, so I skip breakfast and lunch M/W/F).
Another, as you said, is our craving for sugary/fatty/salty things and the means to control this type of hunger are completely different (for example fasting).
As for OPs theory, it's strange to think of such a thing happening during an obesity epidemic, but many people do seem to be lacking basic nutrients in their diet. I'm not sure how much we can trust our own guts when it comes to seeking out nutritious foods; the majority of people go for sugar and fats when they're hungry, instead of the fruits and vegetables that contain the nutrients they're lacking. It seems our stomachs are not looking out for our best interests.
[1] https://hub.jhu.edu/2013/12/17/vitamins-might-be-harmful/
We know that B12 needs to be supplemented in people who are deficient, and that medicos sometimes give B12 injections.
We know that pregnant women who take folate supplements have babies with fewer neural-tube defects (spina bifid etc).
We know that we need to put some B vitamins back in the flower after it's milled otherwise the psychiatric wards fill up.
We know that people who ingest less than the recommended daily intake of Chromium (less than 50mcg per day) have more blood sugar disregulation[1].
So why not put these things together in one package, where and when it makes sense to do so.
I'll admit that some multivitamins are badly formulated, and I actively discourage people from taking certain forms of nutrients. Eg. why does any manufacturer put iron oxide or magnesium oxide in their supplements? These things are poorly absorbed and have known negative side effects.
(Obviously specific supplementation where required is good and useful. I object only to the "mix it all together" approach as both unproductive and an attempt to treat a problem in the wrong place.)
https://www.consumerlab.com/answers/Which+vitamins+and+miner...
> did you know that caffeine inhibits iron absorption (among others)
Yes, I'm aware of that.
> And if you have one
See your fist point. Caffeine, and other stressors increase demand, either by reducing absorption or increasing elimination. Some people have genetic weaknesses, or lifestyle factors, that cause them to be prone to needing more of certain nutrients.
To be fair, I generally agree with what you're saying. Throwing it all in a big bucket and hoping for the best isn't very good clinical advice.
There are, however, some good nutritional supplements that have synergistic formulations.
Full disclosure: I studied nutrition and have qualifications recognised in Australia.
Right. Our appetite is adapted for pre-industrial times, when craving sweet berries while they are in season would be a good thing. We're not equipped to handle constant availability of sugared and MSG-laden processed foods that are actually designed to defeat natural satiety mechanisms.
I would be cautious of demonizing fats; unprocessed fats haven't been shown to do much harm. In recent years, even Harvard Med School has backed off of low-fat recommendations, instead saying trans-fats ought to be avoided. https://www.hsph.harvard.edu/nutritionsource/what-should-you...
There's one way in which our appetites do point in the right direction: veggies are tastier and more appetizing when paired with butter or sauce, which also make it possible to absorb fat-soluble vitamins from the veggies.
What's the evidence of that?
Note that 'required' likely means "less than the RDA" and that RDAs are often set on the basis of "having less than this much will imminently lead to some sort of dysfunction" as opposed to "the amount that actually makes your body happy".
If you don't have calories your hunger wont be satiated because of energy needs.
Vitamins don't absorb as well as nutrients found in foods (they have a low gut surface area and may not contain the easiest molecules for your body/gut to breakdown into nutrients).
In my personal experience a complete protein powder (like PlantFusion products) has a strong effect on general satiety as well as health unlike vitamins.
and you're not likely to get the best version in that multi vitamin.
I also have a 23andMe account and looked up to see if I have the FGF21 gene?
I found that I have 2 SNP's on gene FGF21.
http://i.imgur.com/qnRD5M4.png
Any idea what this means relative to the study?
[1] http://www.mayoclinic.org/diseases-conditions/factor-v-leide...
"This revealed statistically significant associations between FGF21 rs838133 and increased consumption of candy, as well as nominal associations with increased alcohol intake and daily smoking."
rs838133 is the first one in the table shown in image I linked to.