I strongly suspect an issue with insulin or glucose metabolism yes, but doctors have not taken me very serious on it. 10 years ago i was sent to an endocrinologist which did a glucose tolerance test on me because of fatigue following a meal, the result showed elevated levels. I still can't drink a can of soda or anything loaded with sugar, it sends me into a foodcoma within 20 minutes!
I have a glucosemonitor and the results always come back fine. Fasting glucose measured in lab is also always fine.
You mention Thiamine. I tried Thiamine 6 years ago and noticed an immediate effect, like it cleared my brain fog. I had to stop using it after 2 days because of an IBD-flare.
Which amino acids are you taking? Just a BCAA formula? I find it helps me too, it really gives that bit of extra energy during a workout but somehow it highly increases my metabolism! I don't want to loose too much fat because i'm already so skinny.
I suffer from IBD, many allergies & inyolerances and now possibly also MCAS. Meat is actually one of the only few things i do digest and tolerate. Dairy and vegetable proteins on the other hand....
I was very into weight training before i became ill. Lost about 25 kilo's in muscle mass. I'm skin over bone and unable to gain any weight, no matter what i eat.
I used to fall asleep within about 20 minutes of eating - super fatigue - turned out it was Gastroparesis, my stomach wasn't emptying rapidly enough. So what happens is your body thinks "food on board" releases insulin, but the food doesn't show up. It's stuck in the stomach and it's slow through the lower intestine and then that allows really pathogenic bacteria to grow and a whole world of problems. There are several bad things that get triggered all at once, and you end up very very tired.
I am plant based, but had to lower some of the fiber. (white rice instead of brown, white bread instead of whole wheat, broth, soups, beans diluted in soup or with the rice, smoothies but small sized, some fruit is okay under 1 cup). I also have IBD, so tomatoes are a no go, if I eat them I get sores through my stomach and small intestine. Citrus also. I can't eat oats, they take too long to digest -- no whole grains. Basically have to keep things pretty bland because my stomach doesn't empty as quickly as it should and I'll get sore spots. Dairy is a no go, I thought I would add in a little whey and I just ended up with a two day migraine.
A Chinese nurse told me I had a tired stomach. And I should treat it like it was tired, give it bland well boiled mushy rice in water and some boiled veggies. So far so good. I liked how she explained it.
Meat, fat, dairy, eggs make the GI slower and my GI is already very slow -- so they're off my list. (TMI -- I can't poop when I eat those things, it feels like I need to, but even when I do go it doesn't feel 'finished' common IBD type stuff but very annoying.) Too much fiber and I blow up like a balloon. I look pregnant. Fiber sometimes feels like I swallowed pine cones and it hurts all the way down, but it improves my energy -- so I think it feeds the good bacteria and they're mightily happy, but my gut is just TIRED and it needs the more gentle foods for now. I hope to gradually add in more fiber and a wider variety of food with time. Slow and steady.
So yeah, it's something I'm working on fixing and I'm getting better.
My blood work would come back a little elevated i.e. prediabetic, my liver enlarged, my heart had some damage but the doctors shrugged it all off - but I thought - okay, I have a metabolic issues, absolutely, and I have all these health problems -- it's got to be connected.
So daily I take:
L-Glutamine (gut lining)
L-Tyrosine (thyroid support, mood)
L-Theanine (mood)
and I have a protein shake after I work out, currently a Soy one as dairy refuses to be my friend although I think whey works better.
I don't really take BCAA's. I usually take an EPA /DHA, Vitamin D, B12, and Magnesium.
PPI drugs (i.e. like Prilosec), Lithium, Benedryl and many other drugs can cause gastroparesis. So can dieting. I did a nice cocktail of all those things and I think I put this evil on myself. I sometimes had the nausea classic of gastroparesis but not maybe as often as classic GP, additionally with IBD -- I was so used to feeling awful and being aware of food in my GI -- it's kinda hard to know what "normal" is after awhile.
As long as I'm avoiding too much fiber, following a 100% plant based diet albeit not a standard WFPB diet, and getting in a little exercise everyday my GI seems to be happy -- until my period hits. That absolutely mucks up my GI like nobody's business. UGH.
I also get gastritis really easily which is a stomach issue. So when I would go into my doc and I had stomach issues, upper GI, lower GI and fatigue -- they didn't know what in the heck to do with all that.
The so-called, "carnivore" diet is being used to treat this whole amalgam of stomach / GI issues at the moment by a few people - I'm following along to see what happens with that. You can probably type that into Google, Jeff Rogan did a couple of interviews with people who did the Carnivore thing, one man and his daughter only eat beef and salt.
This condition is so miserable that people have done some really weird stuff to free themselves from it and it's kinda a big war online at the moment and has really blown up since Rogan had a few interviews with people like Shawn Baker and popular Vegans took on the issue like GogiMan and Vegetable Police. I've been watching this conflaguration with interest -- mostly because I always felt really alone with my GI problems and my fatigue. I felt like a freak. Turns out it's not that unusual or rare. Wow. I will watch how that resolves and keep that "only eat beef" in my back pocket if I ever get to the next level of desperation. I really don't like eating critters unless it's a fish, fish have it coming, but I normally don't eat them either.
This is going on far too long....
Hey Good Luck to you - I hope you found something I said useful if it wasn't tl;dr *Cheers*