In a word No.
The primary ingredient in Slimfast is sugar. A foundation principle of Southbeach is to severly limited processed foods.. and stabilize your blood sugar through eating foods in lower GI and GI loads. Here is an extract on slimfast from http://www.ultimatefatburner.com/rev...fast-diet.html
So what's in a Slim Fast diet shake?
The 4 main ingredients are skim milk, sugar, fructose, and cocoa. In other words, milk, sugar, and sugar. Other ingredients include various vegetable oils, emulsifiers, and a dubious vitamin blend. A 375ml (1.5 cups) shake contains 12 grams of protein -- slightly less than what you'd obtain drinking the same amount of 1% low-fat milk. This same shake contains 38 grams of carbohydrates -- 20 grams more than if you drank the equivalent amount of 1% low-fat milk (with those additional carbs coming from the added sugar). Considering that milk contains significant amounts of vitamins A and D, Riboflavin, Niacin, Vitamin B12, Calcium, Phosphorous, Magnesium and Zinc, I'd suggest that you chuck the Slim Fast shakes (vitamin blend and all), and simply drink milk instead.
OK... that's problem number 1 -- the shakes are little more than an expensive, sugar-laden milk supplement.
What's Wrong with the Slim Fast diet?
The daily caloric limit is set so low as to be detrimental to any long term weight loss success (each shake contains 240 calories. Couple two with a normal dinner consisting of a chicken breast, baked potato and vegetable, add a snack or two a day and you're looking at anywhere between 1000 - 1200 calories per day).
Good luck- Ihope you reconsider your approach and read the SB book or other healthy diet plans - many of us have alot of weight to lose.-but also realize that we have to change our eating habits and lifestyles to continue to lose in a healthy way and maintain that loss