Personal trainer Wendy Chant's "Crack the Fat Loss Code" diet is relatively healthy for a commercial diet plan. She encourages lifestyle change over temporary deprivation, and she teaches dieters how to choose healthy foods instead of eliminating entire food groups. That said, there are a few aspects of the plan that may make adherence difficult for some people, and adherence is a big part of any diet plan. Unless you stick to it, you won't lose weight.
Unlike typical fad diets that keep you on a static calorie intake and macronutrient ratio for the duration, the CFLC diet consists of four separate phases, each with a distinct eating pattern. Your day-to-day diet varies even within each cycle, which can lead to confusion. This constant variation is the mechanism behind the weight loss and the philosophy around the whole diet, so there is not much wiggle room. Fortunately, the plan is well laid-out in the book, but it would require daily consultation to keep track of what you're supposed to eat.
One of the main tenets of the CFLC diet is that there is no calorie counting. This can be a relief to frustrated dieters weary of weighing and measuring everything they eat, but it can be just as pedantic. Chant's solution to the calorie and macronutrient confusion is a series of pre-planned menus. Having your exact meals planned for the entire diet may seem convenient, but you'll run into trouble if you don't like one of the foods. If you can't stand mushrooms, you must figure out how to replace that exact same number of calories and nutrients for that meal without wrecking the balance. The diet cannot consider any individual food allergies, as well. Like most pre-planned menus, there is little guidance in this respect, and DietsinReview.com notes that the meal plans do not accommodate vegetarians.
Requires Frequent Meals
Chant requires dieters to eat four to six small meals per day to keep the metabolism and thyroid stoked. However, thyroid function does not depend on meal frequency -- either your thyroid functions properly or it doesn't, and changing your meal habits won't affect it. Eating several times per day can help you keep your blood sugar levels steady and avoid "crashes" that occur between meals, but it doesn't affect fat loss. Additionally, many people have daily schedules that don't allow them to take time out to eat every two or three hours, which may affect their ability to stick to the plan.
Not Scientifically Proven
The diet is based on macronutrient cycling, which although it is an interesting concept, has not been proven effective for weight loss. The cycling aspect focuses mainly on carbohydrates, allowing a high carb day, a low carb day and a very low carb day, repeated in succession. In theory, this allows you to periodically restock your glycogen stores, then deplete them, forcing your body to burn fat for fuel. Because your glycogen stores last about 72 hours, your first day of majority fat burning would occur the same day as your next high carb cycle, which would replace your glycogen. Because glycogen binds with water in the body, you'll likely notice water weight gain followed by water weight loss, but any permanent fat loss is likely the result of the healthier food choices. There is simply no evidence as of 2011 to suggest that macronutrient cycling is effective for permanent fat loss.