Does Slim Fast Work Quickly?

Slim-Fast is a commercial liquid diet. The company also sells small snacks and foods, such as meal bars and instant soups, but its shakes are the most important part of its weight loss program.

Slim Fast made in different flavors. Credit: margouillatphotos/iStock/Getty Images

How It Works

The Slim-Fast diet plan recommends eating three meals plus two or three snacks a day. Two of your meals should be Slim-Fast shakes or bars. For snacks, choose fruits and vegetables or a small snack bar from the selection. Your third meal of the day -- which can be breakfast, lunch or dinner, depending on your preferences -- should consist of "real food," such as lean protein and a salad. You should start noticing results by the end of the first week.

Recommended Weight Loss

Slim-Fast recommends a weight loss of 1 to 2 pounds per week. This is the same amount medical experts such as the Centers for Disease Control and Prevention recommend. Slow weight loss is best because it's more likely to be fat loss rather than water or muscle loss. If you are severely overweight, a 2-pound weight loss might not be immediately noticeable to the naked eye, so check your weight on a scale once a week.


Slim-Fast recommends an exercise program to go along with your dieting efforts. If you implement this, your weight loss will speed up significantly. Everybody following the program should do at least 30 minutes of walking on most days of the week. If you want faster weight loss, aim for 60 minutes a day.


You might lose more than 2 pounds during the first couple of weeks on Slim-Fast, especially if you were eating large amounts of food before and now are drinking the shakes in its place. If you continue to lose more than 3 pounds per week after the first two weeks, you will need to adjust your food intake to slow it down to the ideal 1 to 2 pounds per week.

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