How does the body signal hunger for protein?

[StrongMom]

Yeah, we start craving food with protein, but does anyone know what types of hormones, etc. signal that? We know how it works for sugar: i.e., glucose-insulin cycle. Is there something like that for protein as well?

Thanks

 

[cantstoppeating]

No.

 

[StrongMom]

But there should a mechanism for your body to tell, right?

 

[kineticz]

Only glucose or fats are needed for energy expenditure. Protein and amino acids mediate cell renewal and cholesterol transfer.

 

[PeatMonster]

Actually I remember seeing a study that suggested it had to do with serotonin. Not sure where it is right now, but the gist was that high serotonin triggered protein cravings in rats. The rationale was that most protein sources have enough of the large amino acids that compete with tryptophan, so protein tends to lower serotonin, sending a message to the brain that protein consumption was adequate. If its true that exercise causes increased serotonin because cortisol liberates a disproportionately high amount of tryptophan from tissue, then this could explain why weightlifting makes people crave meat.

 

[StrongMom]

Actually I remember seeing a study that suggested it had to do with serotonin. Not sure where it is right now, but the gist was that high serotonin triggered protein cravings in rats. The rationale was that most protein sources have enough of the large amino acids that compete with tryptophan, so protein tends to lower serotonin, sending a message to the brain that protein consumption was adequate. If its true that exercise causes increased serotonin because cortisol liberates a disproportionately high amount of tryptophan from tissue, then this could explain why weightlifting makes people crave meat.

That is interesting PeatMonster, but does it explain the cravings I get for meat after a few days of meat-free diet (i.e., dairy and eggs being the main protein source)? I tend to think that my body is missing some of the nutrients in meat and through a mechanism signaling by cravings.

 

[PeatMonster]

Actually I remember seeing a study that suggested it had to do with serotonin. Not sure where it is right now, but the gist was that high serotonin triggered protein cravings in rats. The rationale was that most protein sources have enough of the large amino acids that compete with tryptophan, so protein tends to lower serotonin, sending a message to the brain that protein consumption was adequate. If its true that exercise causes increased serotonin because cortisol liberates a disproportionately high amount of tryptophan from tissue, then this could explain why weightlifting makes people crave meat.

That is interesting PeatMonster, but does it explain the cravings I get for meat after a few days of meat-free diet (i.e., dairy and eggs being the main protein source)? I tend to think that my body is missing some of the nutrients in meat and through a mechanism signaling by cravings.

1. It would explain that if dairy and eggs are simply inadequate protein sources. I have the same issue in that I simply can't seem to keep it to dairy and eggs. Your body may be saying that it's had too much of the other components of eggs and dairy (fat, lactose) but still needs protein.
2. There aren't many nutrients in meat that aren't available from eggs and dairy or other foods. It seems like creatine deficiency could be an issue, though I don't know what hormones are involved in signaling creatine deficiency.
3. Bizarrely I think the actual answer (at least in my case) is glucose deficiency. Sucrose and fructose do a poor job of refilling muscle glycogen. But glucose does a good job of restoring muscle glycogen, and the body gluconeogenisis makes glucose out of amino acids. If you (like me) have been low carb for awhile, your body may have the idea that meat is a good source of amino acids to synthesize glucose. If you eat starch, I would say try eating some starch when you have a meat craving and see if it satisfies. If it doesn't this isn't the problem. If you don't do starch, you could try maltodextrin as an experiment but I wouldn't make that common practice.

 

[PeatMonster]

Addendum: This is a more direct answer to your question - the reason the serotonin theory could still apply to your situation:

Even if you are getting adequate protein from milk and eggs, they are both more insulinogenic than if you were to get the same amount of protein from a different source. The problem with this is that insulin triggers muscles to take up large amino acids which would normally compete with tryptophan at the blood-brain barrier. The net result of both foods might actually be higher serotonin and therefore less "protein-satiation" for the same amount of protein. Most people don't seem to have this problem, but if you do, one way to solve it is by reducing the insulin impact of the other foods you eat. So you would stick to sucrose/fructose over starch (note: the exact opposite of the advice in my prior response). I'm pretty sure either one could be correct depending on your situation. If you do alot of physical activity and don't eat much starch I'd lean toward glucose deficiency. Otherwise serotonin excess. Note: gluconeogenis may be a fairly safe way to get extra glucose anyway if you don't tolerate starch.

 

[SQu]

3. Bizarrely I think the actual answer (at least in my case) is glucose deficiency. Sucrose and fructose do a poor job of refilling muscle glycogen. But glucose does a good job of restoring muscle glycogen, and the body gluconeogenisis makes glucose out of amino acids. If you (like me) have been low carb for awhile, your body may have the idea that meat is a good source of amino acids to synthesize glucose. If you eat starch, I would say try eating some starch when you have a meat craving and see if it satisfies. If it doesn't this isn't the problem. If you don't do starch, you could try maltodextrin as an experiment but I wouldn't make that common practice.

Very interesting and helpful to me too. I was struggling to understand why when I can feel I'm in the stress hormone state sugar doesn't always help. Not cheese either. Nothing seems to. I end up eating ice cream or finding a proper meal about the best.

 

[Amazoniac]

If your dietary protein is very low, your organism will probably have to triage the protein that's available, targeting to more important places; taking from skeletal muscle to cardiac muscle for example. So the hormones involved are probably hormones that assist catabolism - I guess this is why when people are protein deficient they usually crave sweets, in an unsatiable manner.

 

[StrongMom]

3. Bizarrely I think the actual answer (at least in my case) is glucose deficiency. Sucrose and fructose do a poor job of refilling muscle glycogen. But glucose does a good job of restoring muscle glycogen, and the body gluconeogenisis makes glucose out of amino acids. If you (like me) have been low carb for awhile, your body may have the idea that meat is a good source of amino acids to synthesize glucose. If you eat starch, I would say try eating some starch when you have a meat craving and see if it satisfies. If it doesn't this isn't the problem. If you don't do starch, you could try maltodextrin as an experiment but I wouldn't make that common practice.

Very interesting and helpful to me too. I was struggling to understand why when I can feel I'm in the stress hormone state sugar doesn't always help. Not cheese either. Nothing seems to. I end up eating ice cream or finding a proper meal about the best.

I think that applies to my situation as well. I have been trying to reduce my reduce starch consumption for a while. I think I ended up eating more sugar, fat, and protein instead. Also interestingly, my sugar cravings are mostly gone, and there are times I really don't want to eat sugar. That is very unusual for me. Maybe my body is craving for glucose.

 

[oxidation_is_normal]

Why do we need to explain each piece of information we get from the body in order to trust the body? I think this impulse to trust the body after everything else is less healthy than eating whatever it desires in the long term.