Low-Carb Vs. Low-Fat Diets

July 19 -- In the fight against fat, Noreen Hunter is a battle-scarred veteran. For most of her life she has struggled to lose weight with one low-fat diet after another.

Hunter, 46, did lose weight, but she always gained it back. In the past year alone she has regained 50 pounds. No wonder she's thrown in the towel and is now trying a diet that seems sinful. It's high in fat and low in carbohydrates.

But to do this, she's had to get over years of brainwashing that says fat is bad. "You have to de-program yourself to thinking in a different way, that maybe something else is going to work."

Hunter is part of a diet revolution that is sweeping the country. That's because for the past 20 years, while Americans have been religiously following low-fat diets, they've actually been getting fatter.

But "What If Fat Doesn't Make You Fat?" asks science writer Gary Taubes in a recent New York Times article in which he addresses what he considers the bad science that's lured millions to low-fat diets.

"What we believe to be true with such certainty could just be a sort of mass delusion, wishful thinking that the medical establishment inflicted on us, and it just snowballed," Taubes told 20/20 in an interview with ABCNEWS medical editor Dr. Timothy Johnson.

A Myth in the Making

"The theory was that a low-fat/high-carb diet would control weight and help prevent killer diseases. But most of the studies that followed actually failed to show a direct link between fat in the diet and heart disease and cancer. But by then it was too late — even science couldn't shake the prevailing wisdom that all fats are bad, and all carbs are good," explained Johnson.

By investigating the genesis of this theory, Taubes found that the government's initial decision 30 years ago to promote low-fat diets was not based on recommendations from doctors or scientists, but rather from lawyers who worked for Sen. George McGovern in the mid-1970s.

"They come out with this document and it just sets this ball rolling where finally some government body is telling Americans to eat less fat and eat more carbohydrates," Taubes said.