I used the Slim Fast plan for about 6 months. That with vigorous exercise helped me shed 42 pounds. However, there was a LOT of exercise involved! I was biking 15 miles EVERYDAY! Now that I look at that plan, it is nothing more than a reduced calorie diet, however it has LOTS of sugars in it. Atkins Shakes are better with (most) less than 1 g of sugar and readily available off of the shelf. Just my 2 cents worth.