South Beach Diet is one of the newer diets and has some sound science behind it. Dr. Agaston, a leading cardiologist in Florida, created the South Beach Diet for his heart patients, but discovered it had the side effect of significant weight loss. He claims that it is neither a low carb or low fat diet, rather focusing on the "right carbs" and fats. It imitates other diets in several ways--like Atkins it cuts carbs severely for the first two weeks--this is designed to give your body a rest from fluctuating blood sugar levels. Then like the GI diet it brings back low glycemic index "good" carbs in gradually. It also swaps saturated fats for unsaturated fats. See our review of the GI diet for more detail on how the South Beach Diet works.
Like the GI diet, this is as much a lifestyle as a diet, and you probably won't see huge, quick weight losses (save for the first two weeks, which, like Atkins, can be dramatic). You may prefer to try a quicker diet initially to jump start losses and switch to this for most of your dieting.
Menu: In Phase 1 South Beach is like Atkins, eating many high protein/fat things like meat, cheese, etc. Then Phase 2 introduce low GI foods like whole grain cereals and breads, low-fat milk, pasta, etc. Finally Phase 3 for maintenance brings in even more foods and is designed to be used indefinitely as a lifestyle rather than a weight-loss diet.
Prices: Dr. Agaston's book costs only ~$10 on Amazon. Prices for the food varies, but isn't too bad compared to some diets.