How Much Weight Can You Lose When Doing the Special K Challenge?

Kellogg's promotes a weight-loss challenge that uses their Special K cereal as a meal replacement. By replacing two meals daily with a bowl of the cereal, the company claims you can lose up to six pounds in two weeks. How much weight you'll really lose depends on your starting weight, your age, gender and activity level. Note that the Special K Challenge is promoted as a temporary weight-loss solution. Before starting this plan, consult with your doctor to determine if you need to lose weight and if it's safe for you to try.

By replacing two meals daily with a bowl of the cereal, Kellogg's claims you can lose up to six pounds in two weeks. (Image: NPHOTOS/Moment/Getty Images)

What Is the Special K Challenge?

When following the Special K Challenge, you consume a 45-gram serving of Special K cereal -- equal to about 1 1/2 cups of the original flavor -- at two meals during the day. The third meal you eat should be well-balanced and of your choosing. The plan also encourages you to exercise modestly on most days, such as dancing to your favorite tunes or walking 10 to 20 minutes at lunchtime.

The company recommends you be at least 18 years old and at a body mass index of 25 before trying the plan. They include a BMI calculator on the website so you can figure out your BMI in seconds. A BMI greater than 25 indicates that you may be overweight, but it's only one of many screenings that your doctor uses to determine the health of your weight. The Special K Challenge also includes warnings to consult your doctor before starting the challenge if you're on medications or if you need to lose 20 percent or more of your body weight.

How the Special K Challenge Leads to Weight Loss

The Special K Challenge uses the principle that, to lose weight, you must eat fewer calories than you burn. By substituting cereal for two meals each day, you'll most likely take in fewer calories than if you ate a complete meal at those sittings.

A 1 1/2-cup serving of the original cereal with a cup of non-fat milk equals about 260 calories, which means your breakfast and lunch combined on the Special K Challenge contain just 520 calories. You're on your own in planning your third meal, which Kellogg's suggests should be "balanced." The Special K Challenge doesn't give you a specific calorie allotment for the meal or specifications for its makeup; however, the website suggests you consume lean proteins and beans or legumes at meals. The amount of calories in this third meal determines how many pounds you'll lose over the two-week plan.

Figuring Your Weight Loss on the Special K Challenge

To help figure out how many calories you'll lose during the Special K Challenge, use an online calculator to determine your daily calorie needs. This calculator should take into account your activity level, age, gender and your current weight.

Once you know this number, subtract from it the 520 calories from your two cereal meals as well as the calories from your third meal, determined using an online calorie-counting program. Use the remaining number to estimate your rate of loss.

For example, say the online calculator figured you need 2,000 calories to sustain your weight. If your non-cereal meal contains 600 calories, for example, your total daily intake will be 1,120 calories: 2,000 - 520 in cereal - 600 meal calories = 1,120 total calories eaten. Subtracting 1,120 from 2,000 leaves you with a daily deficit of 880 calories or a weekly deficit of 6,160 calories: 880 x 7 = 6,160. A pound of fat contains 3,500 calories, so divide 6,160 by 3,500 to get 1.75. So, in this example, you'd lose 1.75 pounds per week -- or 3.5 pounds over the two weeks of following the Special K Challenge -- if your non-cereal meal contained 600 calories every day.

Special K's estimation of a three-pound loss per week is based on a person who consumes fewer calories at the third meal and/or requires a greater number of calories to sustain their current size. Losing weight at a rate faster than 2 pounds per week for an extended period of time is not usually recommended by health organizations, such as the National Institute for Diabetes and Digestive and Kidney Disease, due to the risk of developing gallstones. A gradual weight-loss is more likely to be sustained for the long term, too.

Considerations With the Special K Challenge

The Special K challenge offers sound dietary advice, such as limiting portion sizes, drinking ample water, sticking to foods low in saturated fats, eating plenty of beans to boost your fiber intake, sleeping well and destressing. When followed for just two weeks, the Special K challenge may help you drop pounds for a special occasion, such as your high-school reunion. The challenge can also help you jump start a long-term weight-loss plan.

But, consuming just cereal for two meals per day for the long term may leave you without the fiber, protein and many of the vitamins and minerals you need for proper growth, energy and optimal wellness. The original cereal, for example, provides no dietary fiber -- which helps you feel full and supports healthy digestion -- and only 9 grams of protein per 1 1/2-cup serving. Even with the milk, you'll get about 17 grams of protein per meal. When trying to lose weight, you want 0.55 grams per pound of body weight to preserve lean body mass and keep you feeling satisfied, notes a review published in a 2012 issue of the British Journal of Nutrition, which, for a 150-pound person, this amounts to 83 grams per day. So with 34 grams of total protein from the two cereal meals, this person would need to eat about 50 grams of protein at the other meal, which is a lot for one sitting.

Special K also has no calcium and just 10 percent of the daily value for vitamins A and D. If you add 2 cups of milk to your cereal meals, you do contribute some: 20 percent of the DV for vitamin A, 60 percent for calcium and 40 percent for vitamin D. You'd need to make up the balance of these nutrients in your one "balanced" meal per day. You may also miss out on getting enough of certain B vitamins and vitamin C.

After the two weeks, switch to a long-term weight loss plan that includes a variety of whole foods at all meals. You may still enjoy Special K at one meal, but at the two other meals and snacks, enjoy lots of vegetables, lean proteins and whole grains to provide the nutrients to support a healthy body and help you lose weight.

Eat Enough Calories While Following the Plan

If you use the Special K challenge, make sure you still consume enough calories to support good health and expedient weight loss. Eating fewer than 1,200 calories as a woman or 1,800 calories as a man, even when trying to lose weight, puts you at risk of nutritional deficiencies and a stalled metabolism. For a man to do the Special K challenge and still take in enough calories to prevent muscle loss, he'd have to consume almost 1,300 calories at his "balanced" meal -- which is a lot for one meal. He may want to spread those calories out over the course of the day to manage hunger, energy and digestion. Use the cereal at meals, but include a healthy snack between bowls, such as fruit, a scant handful of nuts or low-fat yogurt, for example.

Although the Special K Challenge does encourage you to exercise, it doesn't provide any substantial guidelines as to how to do so. Exercising when you're trying to lose weight helps you achieve your calorie deficit and promotes the maintenance of muscle mass, which is critical in keeping your metabolism humming and your body healthy. Aim for a minimum of 150 minutes per week of moderate-intensity cardio, such as brisk walking, and two total-body resistance training sessions.