What Is in Slim Fast?

Slim-Fast is the brand name of a meal replacement shake manufactured by Unilever. This milk-based, calorie-controlled beverage is designed to encourage weight loss. Slim-Fast comes in a ready-to-drink can or in powder form in a variety of flavors. Like other meal replacement products, Slim-Fast contains one or more sources of protein, carbohydrate and fat, vitamins and minerals, as well as flavorings, emulsifiers and other ingredients.

Protein Sources

All ready-to-drink meal replacement beverages contain protein, typically a "complete" protein source, either soy- or animal-based, that provides all of the amino acids essential for human health. Slim-Fast contains fat-free milk as the first ingredient, thus, the protein source is whey and casein. In addition to that, Slim-Fast shakes contain additional protein in the form of milk protein concentrate and soy protein isolate. Depending on the variety, Slim-Fast shakes offer between 10 g to 20 g of protein per 325 ml serving.


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Slim-Fast shakes, on average, contain about 25 g of carbohydrates (18g sugars, or 4.5 tsp.). The carbohydrate, as well as the sugars, comes from milk as well as regular sugar. Sugar is the third ingredient after fat-free milk and water. Another source of carbohydrate in Slim-Fast is maltodextrin. Maltodextrin is a digestible carbohydrate that is absorbed by the body as rapidly as glucose. It is made from corn or rice starch and is often used as a food additive and/or a source of carbohydrate in sports drinks. It is typically mildly sweet or flavorless.


Each serving of Slim-Fast provides about 6 g of fat (1.5 g saturated). Half of the fat in Slim-Fast is heart-healthy monounsaturated fat that comes from canola oil, which is the fourth ingredient. Slim-Fast shakes also contain mono- and diglycerides. These are fats, made from oil, that act as emulsifiers. Emulsifiers give a product a consistent texture and prevent separation. They enhance creaminess and stabilize a product to improve the consistency. Slim-Fast also contains soy lecithin, which is another emulsifier that keeps cocoa and cocoa butter from separating in confectionary items.

Vitamins and Minerals

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Slim-Fast is fortified with 23 essential vitamins and minerals to enhance its nutritive value. On average, each drink meets about 30 percent of the Recommended Daily Value (DV) for most of these nutrients. It is particularly rich in vitamin C, E, phosphorus and calcium, meeting 50 percent to 100 percent of the DV for these nutrients. Except for nutrients naturally found in milk, such as calcium, vitamins A, D, B12, potassium and riboflavin, other vitamins added to Slim-Fast are in synthetic form. Some synthetic nutrients are better absorbed than naturally occurring vitamins and minerals, such as folic acid, but others are less well absorbed in synthetic form, such as vitamin E.

Other Ingredients

Other ingredients in Slim-Fast have various purposes that have more to do with the consistency, appearance and flavor of the beverage than the nutrition. Gum Arabic is high on the list of ingredients. It is used in the food industry as a stabilizer. It is also used in the textile and cosmetic industries—even in glue. Sodium, preservatives and flavorings, both natural and artificial, are additional ingredients in Slim-Fast. Some ingredients vary by flavor. For example, the Cappuccino Delight flavor has both cocoa and coffee powder added.