Optifast is a controlled-portion diet plan that requires medical evaluation and frequent follow-up. The diet provides very few calories for the first 12 weeks, usually 800 calories a day. During its first phase, no food is allowed outside of the pre-packaged Optifast meal replacements. After the initial phase, you transition to regular food slowly, under the guidance of a medical team. Weight loss averages 52 pounds in the first 22 weeks, according to the Optifast website.
The Optifast diet includes ready-to-drink shakes as well as powders that contain 160 calories each, for a total of 800 calories in five servings. The shakes come in three flavors: French vanilla, chocolate and strawberry. Each shake supplies 14 g of protein, for a daily total of 70 g, enough to satisfy your daily 60-g protein intake, according to the Merck Manual of Medical Information. Each shake also supplies 20 g of carbohydrate, or 100 g per day. The average daily intake of carbohydrate is between 50 and 55 percent of your daily calorie intake, according to Merck, which would equal 400 to 440 calories on an 800-calorie diet. Since 1 g of carbohydrate contains 4 calories, Optifast supplies 400 calories of carbohydrate, or 50 percent of your daily calorie intake. The shakes contain no fiber and only 3 g of fat each, for a total of 9 g of fat per day, which classifies the diet as low-fat.
The nutrition bars offered on Optifast come in three flavors: chocolate, peanut butter, and chocolate and berry with yogurt coating. The bars, which serve as meal replacements, supply essentially the same number of calories, proteins and carbohydrate but contain 4 g of fiber per bar or 20 g per day if you choose bars for every meal. Fiber in your diet helps prevent constipation and also promotes a feeling of fullness. Men under age 50 require 38 g of fiber per day and women need 25 g, the MayoClinic.com website states.
The Optifast plan includes two soups, garden tomato and chicken. While the soups supply essentially the same calorie, protein, carbohydrate and fat intake as the bars and shakes, they contain considerably more sodium, between 600 and 620 mg per serving. The bars contain between 150 and 190 mg each and the shakes between 220 and 230 mg each. If you consumed all your calories in the form of soup, this would equal over 3,000 mg of sodium per day, well over the 1,500 mg limit recommended by the American Heart Association. High sodium intake can raise blood pressure in some individuals.