Rather than a quick burst of energy during prolonged workouts, meal replacement bars are designed more for dieting and weight loss. They are meant to provide the complete nutrition of a lunch or breakfast and to fill you up. Nutribars and Balance bars are two examples of energy bars designed to replace, rather than supplement, a meal. Each of these bars provides calories from carbs, proteins and fats in proportions that sate hunger.
Some energy bars, such as protein bars, are designed to help you gain muscle mass. These bars attempt to cram as much protein as possible for recovery from strenuous workouts. Pure Protein bars and most Met-Rx bars fit into this category.
Endurance bars are primarily designed to be eaten before a long workout. They typically have a higher proportion of carbohydrates to provide complex, non-sugary energy that is digested over a long period of time. The most well-known endurance bars include PowerBar and Honey Stinger Bars.
Similar to endurance bars, activity bars focus on prolonging energy. However, they tend to focus on all-day outdoor activities that require both energy and some meal-replacement nutritional features. Clif Bar is perhaps the most prevalent bar in this category. Outdoor bars, Clif Bar included, often focus on organic ingredients and have crunchier, more granola, textures.
There are a new wave of energy bars that focus largely on providing energy in as natural a method as possible. Organic bars reject artificial sweeteners and inserted protein, preferring to have a compact load of simple ingredients. Larabar is particularly popular, with an ingredient list that typically includes only a few items and never adds protein, gluten or soy.