The Special K diet plan, also known as the Special K Challenge, involves eating Kellogg's Special K cereal or snack products for two meals and two snacks each day, followed by a healthy evening meal of the dieter's choice. As of 2015, the diet plan is no longer available on the Special K website, but consumers can follow their own version of the diet using Special K products and recipes.
The Special K Challenge lasts for 14 days. On each day, the dieter eats the Special K cereal of his choice for breakfast, followed by a Special K cereal bar for a mid-morning snack. Lunch on the plan usually consists of a Special K meal replacement shake or protein bar, and a mid-afternoon snack is composed of another cereal bar, or a serving of whole grain crackers.
Dinner on the Special K Challenge usually consists of a home-prepared meal based on one of the recipes available on the Special K website. On some days, dieters may choose to eat a homemade meal for lunch and have a protein bar for dinner.
Critics of the Special K Challenge note that the diet promotes an excessive caloric deficit that may lead to an unsafe rate of weight loss. Some dieters may also find it difficult to stick to such a low-calorie diet.