Most low-carbohydrate diets include a starting phase that dramatically cuts overall carb intake. Since this is also typically a high weight-loss period, many people stick to the early rungs or phases of their diet. The problem is, moving on to later phases is where you learn to incorporate healthy portions of fruits and a greater variety of vegetables, among other things. Sticking to the early phases can lead to boredom, which makes "cheating" more appealing, and you also don't get the benefit of learning how to broaden your food variety.