Slashdot Mirror
Geeks and Weight-loss?
WideLoad asks: "A decade or so spent at a desk in the IT industry
has left me with a physique that can best be described as looking like
a half melted wax Buddha figurine. It seems to be a common problem for
those of us whose career and hobby tends to promote a sendentary
lifestyle. With the holiday gorging season upon us and in need of
inspiration and/or motivation I thought I'd ask: what are other geeks
doing about their health?"
It's not true that the body uses up available carbohydrate before starting to burn fat. Different tissues use different sources of energy, regardless of how much is available.
The heart doesn't use carbohydrate for energy. It only burns fat. This means that aerobic exercise, in addition to being good for the heart, has extra benefits for the waist.
The brain, conversely, doesn't normally use fat at all, since fat has trouble crossing the blood-brain barrier. The human brain requires a lot of metabolic energy, so the amount of carbohydrate burned in a day can be fairly significant. Since you use up this energy even if you have your but parked in a chair, this is part of your basal metabolic rate.
Normal muscle (except in the heart) uses either fat or carbohydrate. Of course, this assumes some measure of physical activity. Muscle stores a certain amount of carbohydrate, after which it has to draw carbohydrate from the blood, which gets it from a small reserve of carbohydrate which is stored in the liver after you eat.
The metabolic effect of a very low carbohydrate diet is similar in some ways to untreated Type I diabetes. The brain needs carbohydrate, so the body tries to find a way. Fat is normally stored by the body in a form that connects three fatty acids together with a small carbohydrate molecule. The body breaks up the stored fat into the carbohydrate, which goes to the brain, and the fatty acids, which ends up being waste material. It's not normal for the body to have stray fatty acids around like this, and the fatty acids get shunted through some unintended metabolic pathways, eventually breaking down into acetone and similar substances, which evaporate from the lungs. This type of metabolism is called ketosis, and the resulting sweet-smelling breath (smelling of nail polish remover) was a classic symptom of late stage Type I diabetes in the days before insulin therapy. The diabetes analogy breaks down in that the blood sugar isn't actually elevated.
The whole point of very low carbohydrate diets is to put the body into ketosis, in which fat is broken down into nail polish remover, which is exhaled. This is faster, easier, and less hunger-inducing than exercise. I remain unconvinced that it's healthy.
Low-carbohydrate diets can also be low in water soluble vitamins, since they rely primarily on meat, eggs, and dairy at the expense of grains, legumes, and vegetables.
The excess protein in a low-carbohydrate diet, assuming you're eating meat rather than butter, gets burned up, since there's no good way to make it into fat. This places an extra burden on the kidneys.
If you're heavy because you eat from habit rather than hunger, reducing caloric intake is a good place to start. It's better to start by reducing fat intake, though, since your body already has that in excess. If you're heavy because your appetite exceeds your metabolism, your best recourse is a combination of exercise and reduced caloric intake. Again, the best recourse is to reduce fat intake.