Does the Special K Diet Really Work? may earn compensation through affiliate links in this story.
People sometimes replace dinner with Special K cereal during the two week diet.
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The Special K Challenge is a short-term two-week diet plan designed to kick-start weight loss in people with a BMI over 25, which classifies them as overweight. It is not meant to be followed as a long-term diet. The diet revolves around Kellogg's products, such as Special K protein bars, in addition to Special K cereal or Kellogg's protein shakes, along with fruits and vegetables. One regular meal a day is also allowed.

Diet Components

The Special K diet includes one breakfast serving of Special K cereal, any flavor, with 1/2 cup low-fat milk. A serving of cereal equals 1 cup, according to the Kellogg's website. You eat the same meal for either breakfast or dinner; you may substitute a protein shake or meal-replacement protein bar for the cereal at either meal. The plan includes two snacks chosen from Kellogg products, including snack-sized protein bars, crackers, Special K fruit crisps or protein water mixes. You can snack on fruit or vegetables in unlimited quantities as well. Dinner consists of regular food, but it is limited to low-fat, nutritious choices. Beverage intake is listed as unlimited, but presumably does not include large amounts of regular soda.


To read the diet's instructions on the website, you must register and sign in on the Kellogg's website. However, participants in a study conducted by Loughborough University in 2002, which the diet is based upon, consumed an average of 1,590 calories per day. The diet reduced calorie intake by 27 percent and cut fat intake in half.


In the Loughborough study, weight loss ranged from an average of 2.25 lbs. up to a maximum of 5 lbs., 3 oz. over the two-week period. More than 75 percent of the participants lost inches from their waist, hips, arms, thighs or busts; 33 percent lost an inch or more from their waist.


Special K cereals come in different flavors. Two flavors you can choose from are Chocolatey Delight and Low-Fat Granola. Rather surprisingly, Chocolatey Delight actually contains fewer calories per serving. It has 160, compared to 230 for the low-fat granola. The two cereals even contain the same amount of simple sugars, the kind most often associated with blood glucose level swings, 9 g. The granola cereal contains 6 g protein compared to 2 g in the chocolate version. The chocolate version also contains more saturated fat, 2 g compared to 0.5 g in the granola cereal. Saturated fat can raise cholesterol levels. Both list their trans-fat content, the worst type of saturated fat for your heart, as zero.

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