Human Biochemistry, the basics as relating to dieting.

[thorfinn]

Some of you have probably seen this before in other fora, and I've mean to post it up here for a while, but hadn't summoned enough round tuits. A reasonable chunk of my audience here are quite aware of this stuff already, but there's also plenty who aren't. If you're one of the former, feel free to drop corrections in if any are spotted. And if

Comments

[wildilocks]

Interesting. I've found the most effective wieght loss to come from eating a low-carbhoydrate diet, because your body usually will send you "false" hunger pangs after eating too many carbohydrates, resulting in a very bad cycle of eat crap, feel hungry, eat more crap, gain weight!

I also have in the last 6 months achieved an excellent level of fitness from 2-3 sessions of 1 1/2 hours per week of high intensity cardio workout, and I'm pretty sure I've been mostly eating more, but not putting on extra weight in that time. While you say that anaerobic exercise reduces your metabolic rate for hours afterward, I was always udner the impression that regular higher-intensity workouts raised you BMR overall. Yes or no?

[thorfinn]

"High-intensity" does not necessarily mean "anaerobic". The term literally means "without air" - i.e. your body is burning glucose without using oxygen. Sprinting is so energy intensive that after the first second or so, more energy is needed than there is oxygen to burn, resulting in anaerobic exercise. "Aerobics" is about the level of exercise where almost all the exercise is "aerobic", hence the name. It does teeter a bit on the border between - but that's the idea. The point of "aerobics" is to maximise the amount of exercise that you're doing without getting into anaerobic metabolism. That's not necessarily a point that your particular instructor actually understands, but it's certainly the original reason for the name

Thanks for the info

[velvet_wood]

I found it very interesting, especially as I'm in the process of deciding on a diet and exercise program right now. Things get complicated for me because I have fibromyalgia, and any sort of even vaguely non-gentle exercise leaves me too tired and hurting to move. I had noticed, though, that while I might can only do 5 minutes of fast exercise, that slow, strengthening exercise such as weight-training or yoga does _not_ seem to hurt me nearly as badly, even if I'm doing quite a bit of it. So basically, five minutes of sweating and panting will have me cramped up and collapsing, but fifty minutes of steady, gentle effort won't. From what you've described, this seems to just be an exageration of a normal reaction, rather than something totally unheard of.

Opinions on carb-restricted or low-glycemic index diets? Those are what I'm looking at right now, primarily because they tend to make me feel better and have more energy rather than making me feel exhausted and sick.

Velvet

Re: Thanks for the info

[thorfinn]

One of the things that's fairly clear about fibromyalgia is that there is something distinctly odd going on with metabolic biochemistry. It feels to me (and this is an untested personal opinion) like there is something broken in the glycogen to glucose conversion pathway, resulting in the primary energy pathway being amino acid metabolism (hence the increased nitrogen byproducts of various kinds), instead of more normal glucose metabolism.

The result of that is what you describe - carbohydrate metabolism wouldn't do as much for you as for someone with "normal" biochemistry, because your body mostly isn't burning carbohydrates very well. What also matches is that fast exercise requires glycogen to glucose metabolism, because nothing else produces energy fast enough... Whilst slow exercise can make do with other sorts of metabolism.

What my answer is really boils down to, though, is try it and see. If you genuinely do feel better on a low-GI, higher protein, diet, then it is likely better for you. And definitely stick with gentle

[velvet_wood]

Which is basically the same thing my doctor said. Try it and see, but do so carefully. About the only thing he's said would absolutely be bad is any kind of restricted protein diet. Fibromyalgia is just...strange. There are so many little things that really don't seem like they could possibly be related but are, and treatment is mostly hit and miss. I'm fortunate in having a _very_ good doctor, and having found some things that do actually let me exercise. I've even found a muscle-building supplement, creatine monohydrate, which seems to greatly reduce the amount of pain I'm in afterwards if I take it on a regular basis beforehand. Now if I could find something to improve my memory so I can remember to take it, I'd be doing well.

Thanks,

Velvet

[thorfinn]

Muscle building supplements are generally just powdered amino acids, which is again why I suspect that FM results in primarily amino-acid metabolism being used, rather than glucose metabolism.

And yes, FM is strange... It, and CFS, and a bunch of other things are what I'd class as "chaotic biochemistry" problems. "Normal" biochemistry has lots of swings and feedback loops, and the eventual result of those loops is a relatively stable configuration. What's clear is that something has broken the "normal" biochemistry loops out of the meta-stable configuration, into a "chaotic" configuration, where loops don't quite loop properly... Hence the butterfly-wing tornado effects. Straight out of chaos/complexity theory.

So "treatment", such as it is, is inherently going to be hit and miss, unless you happen across a magic thing which gets rid of whatever strange-attractor is screwing with the biochemistry.

[wildilocks]

Ahhh.. thanks for clarifying there. I'm certainly doing aerobic exercise, and makes more sense now that I'm losing weight very effectively :D