Tuesday, September 22, 2009

Threshold Nutrition

There is a threshold level for glucose, below which insulin is benevolent. Insulin has a vast host of problems, when it is present as a vast host. It will make you a vast host, diabetic, heart diseased, obese. But at an optimal glucose level, all its necessary uses will be met -- brain and organ energy, and whatever else. You ate it, so it’s there, at the right level.

Glycerol is the inevitable waste product of glucose metabolism, and has two functions -- as energy, reconverted into glucose, and as the substrate, the glue of blubber-making triglycerides. If there is no excess glucose in the blood, merely sufficient, or optimal, the resulting glycerol will be used as energy, with a minimal but necessary, optimal, amount left over to formulate triglycerides. We do after all need triglycerides. Bodyfat has a purpose too. Just not so much. Tubby. Sheesh. Go for a walk.

Likewise with protein, amino acids. There is an optimal amount, that lies between an upper and a lower threshold. Too little dietary protein and, well, it’s too damn little. Didn’t you know that? Too much and it just gets turned into glucose, in a very wasteful and expensive process. If that’s the case, why not just eat the carbs? You need as much protein as you need. Any more is redundant and, frankly, stupid.

The constant then should be protein, with focus on the essential amino acids. All other necessary amino acids can be synthesized within the body. The general amount of protein you need to eat can be determined from the nitrogen in urine, and the ideal is to achieve a nitrogen equilibrium. Without references, I recall that the balanced dietary protein level is around five percent of total caloric intake. Obviously athletes would need more, since there is more muscle breakdown. Likewise perhaps with those who are sick or under stress or other exceptional circumstances. What should not happen is that amino acids be wasted by being turned into blood sugar.

The next constant should be glucose. It turns out that the brain uses about 20% of the body’s energy. (My brain would of course use far more than that of ordinary people.) Logically, more than twenty percent of your calories should be from glucose, since there are other needs for bloodsugar. The brain can also use ketone bodies, but that's a backup system. It will always use glucose, even if it has to steal protein from muscles and catabolize it into glucose. Dietary glucose is technically not necessary. Glucose is -- there is a lower threshold. Of course, too much glucose is more than a problem. It is the health problem of the modern age. So there is a huge upper threshold -- let’s turn it into a barrier.

Then there’s fat. Essential fats are essential. The only shortage is in omega 3, and that’s easy to remedy. Of course there are poisonous fats, as excessive carbs are poisonous, and as I say animal proteins are. Poisonous. Transfats. Too much omega 6. But that’s easy to remedy as well. Generally though there are very real health benefits to other fats -- lauric acid, say, or oleic -- and those that are not specifically beneficial are just neutral sources of energy.

Too many calories are a problem because, aside from potential obesity, they get burned off as body heat, and that process creates free radicals, which are damaging and mutagenic and aging and bad. The body can and does regulate its weight homeostatically. It should have to do that as little as possible. Don’t race your engine.

What then is optimal for the macronutrients? Something over 20% for carbs -- brain plus CNS plus organs. Something equilibrated for protein. These seem very much to be not technically constants, but limited to a range. The independent variable, after a few essential grams, is fat. If you’re trying to lose fat you’ve stored, eat it less, so that what you have will be used rather than crowding your blood, even as free fatty acids. If you don’t have a weight issue, it’s all about health and performance. Where are you putting your energy? Lots of thinking? Eat a bit more glucose -- as good carbs. Lots of exercise? A bit more protein, and more fat to supply the muscles. What you don't want to be doing is wasting your energy with digesting more than you needed in the first place.

We do need some common sense. I just finished ch. 19 in Taubes' book. He tells about how good an all meat diet is. Well, I knew it was coming. Hardly anyone is always right. You are very lucky to know me.


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