Which Carbohydrates do we need? And why do we need them?

In a recent Harper's Bazaar article entitled "Get A better Body in Two Weeks", I found the following caveat: "Never cut out carbohydrates completely... If you don't have a sustained energy source, your body will burn muscle for energy." (Harper's Bazaar, August 2008, page 104).

Is that true? Will our bodies burn muscle if we don't eat carbs? I've been seeing that statement, worded somewhat differently each time, in a lot of different places. It's meant to motivate people to avoid cutting out complex carbohydrates from their diet. While we do need to eat some carbs, I think the idea that we would burn muscle if we didn't is misleading.

If we don't have any other energy source, our body will burn muscle. But that happens to people who are starving. Most people in the United States who go on a low carb diet are not starving. The problem is usually that they are too well fed, and they want to get rid of excess body fat.

Fat stored in our bodies represents excess energy that we don't need at the moment, but upon which we can draw, should we need it. Our bodies store fat as a way to ensure that we don't starve if the bountiful food we have available today suddenly disappears tomorrow. Like the fat cows and the lean cows in Pharoah's dream, and the grain storage program that they inspired, our body stores fat as an emergency supply of energy against leaner times. In a famine, people with excess body fat survive. People who have none die. Before they die, their bodies consume muscle for energy.

The low carb diet is helpful for those of us living in this affluent society, where even when the economy is bad, there is still plenty for all to eat. When a very low percentage of our caloric intake consists of carbohydrates, the body resorts to burning fat in order to supply us with energy.

So, do we need to consume carbs? Yes, but not for the energy. Fruits and vegetables are an important part of a healthy diet, and, of course, the calories they supply us with do come in the form of carbohydrates. But the reason it is good for us to eat fresh produce is not its caloric value. Fruits and vegetables are an excellent source of vitamins, minerals, fiber and water, all of which we need in order to keep our bodies healthy.

Vegetables in particular are a poor source of energy, in that they contain relatively few calories per volume, but the other nutrients they provide are well worth the trouble.

So eat plenty of fruits and vegetables for the minerals and vitamins, the fiber and the water. But if you are trying to reduce body fat, then stick to protein and fat for the majority of your caloric intake. Fresh produce is a good source of healthy carbs, but it's not in order to avoid starving that we enjoy these foods. They serve other, equally essential functions.

(c) 2008 Aya Katz