Carbs still can become fat

A few weeks ago, we covered some of the more common diet myths and misconceptions. Here's a bonus myth that's not quite as widespread, but has contributed to a wide spread for many:

You can eat as much carbohydrates (pasta, potatoes, fruits, vegetables, etc...) as you want, because your body won't convert carbohydrates into fat.While it's true our bodies have to work harder to convert carbohydrates into body fat, it still happens. "Fat free" on the label doesn't mean it's a free food.

"Given the choice, your body burns carbohydrates before it burns fat, and it's easier for the body to store [dietary] fat as body fat," said Jeannine Phillip, patient education dietitian at Copley Memorial Hospital in Aurora, "but if you eat a low fat diet and still eat more calories than your body burns, your body will still take those extra calories and go through the process that's more difficult and store those extra calories as body fat."

According to Richard Wolff, RD and director of the Center for Nutrition at Elgin Nautilus, the reason dietary fat is easier to store as body fat is because it has about a 97 percent efficiency rate, while carbohydrates have about a 75 percent efficiency rate.

Simplifying the numbers just a little, Wolff explained it this way:

"Let's say you eat 100 calories above what your body needs," he said. "If you eat fat, say a pat of butter, there's not much the body needs to do to convert it to body fat-structurally, dietary fat is almost exactly the same as body fat. It has about a 97 percent efficiency rate, which means only about three percent of the 100 calories are burned off in the conversion process.

"Now let's say you eat 100 calories of carbohydrates-say, a banana," Wolff continued. "Structurally speaking, the glucose (carbohydrate) molecules don't resemble body fat at all. In order for the body to rearrange the molecules, there is a lot of energy that has to be spent, so your body tends to resist doing it. If it does choose to convert the carbohydrates to body fat, it'll do it at about 75 percent efficiency rate, meaning 25 percent of those 100 calories will be burned off in the conversion process. So if you look at 100 calories, roughly 25 calories will be utilized in the conversion and you'll have a net storage of 75 calories as fat."

And that's where people have been led down the wrong path, Phillip said. "Our bodies are made to store excess calories as fat," regardless of whether the calories come from pure lard or apples. "People have been focusing on counting fat grams and kind of losing site of the calories, and the fact that excess calories will still lead to weight gain."

"Usually most people, if all they did was decrease dietary fat, they'll tend to lose weight...because in most cases, when you reduce fat, calories naturally go down," Wolff added. "But if you really want to fine tune, you need to be cognizant of both calories and fat, and not just one."

� Copyright 1994 Paula Lauer