"Diets work if you use them. They all work probably by the same mechanism, which is that they get people to eat fewer calories."
...among those who stuck with their diets for the entire year, results were slightly better, ranging from a 4 percent loss for Atkins to 6 percent for the Ornish group. Both the Weight Watchers and the Zone dieters lost about 5 percent
The Ornish diet is the low fat vegetarian diet. (Both the Atkins and Ornish diets had higher rates of people quitting (50%) than the weight watchers or zone diets (33%)).
My first year was pretty consistent with the Ornish diet results–I lost 7%, though for my second year I've lost 15% (counting from the starting weight for that year), and I only have 10% more to go.
More evidence against the Atkins diet. Since there are other equally effective tools for weight loss, in a world on the brink of real food scarcity this leads me to call it unethical.