Low-Carb, Aerobic Capacity, and the Metabolic Syndome
Posted Nov 17 2008 9:10pm
It has been interesting to see the results of people experimenting with low-carb diets. Here's one scenario I've read about over and over: went on low-carb, lost weight, fell of the wagon and gained weight. Then a person repeats the cycle.
Usually when people fall off the low-carb wagon, the blame is placed on carbohydrates: carbohdyrates are addicting, carbohydrates are everywhere, etc. And while this may be true to some degree, it doesn't tell the whole story.
Aerobic capacity is a key variable which I believe undelies this whole relationship. Many people talk about a beneficial switch to a more aerobic, "fat-burning" system when they switch to low-carb. This is somewhat true because when carbs are restricted, the body has to rely on protein and fat (or stored carbohydrate) for fuel. But it misses the ultimate point about what fuel an aerobic system truly runs off: oxygen.
There are tons of studies linking aerobic capacity and metabolic syndrome. When a person is in better shape aerobically, they can more efficiently use oxygen/fat to fuel body functions. In effect, they need less carbs to function. I also think the opposite is true: if a person has a low aerobic capacity, they may have a greater desire for carbohydrates. This is because their body runs more on sugar, and they will feel better (at least for a few hours) if they consume more sugar.
Take a person who is elderly and has a low aerobic capacity and put them on a low-carb diet. With no change in exercise levels, I highly doubt you would see any difference in quality of life. But if instead you put them on a program to increase aerobic capacity, they will improve (as studies have shown).
Making the body a better fat-burner requires working both sides of the equation: feeding the body less sugar and exercising in a way that encourages the body to burn fat.