Are "fad diets" weight-losing diets?

Are “fad diets” weight-losing diets?

My dictionary says fad mean fashion. But judging from the context of the articles I read, fad diets don’t seem to mean fashionable diets…

A fad is something that is wildly in fashion for a short time and then quickly disappears. Fad diets are weight-loss schemes that become wildly popular for a short time, and the lose popularity when people find out they don’t work very well.

One of the most recent fads was the Atkins diet. That had been a fad decades ago, but scientists didn’t believe in it. A few years ago it was found that the Atkins diet really could make people lose weight, and suddenly it seemed as if half the population of the United States was on it. Then, a few months later, just as quickly, most of those people stopped following the diet, because they realized it wasn’t balanced enough for people to live on for their whole lives.