Nutrition bars fit into one of four basic categories which include meal replacement bars, protein bars, energy bars and weight loss bars. For the most part, the bars are pretty similar with a couple of specific differences. These bars can vary significantly in their ingredients.

An energy bar that focuses on whole grains will be high in fiber, usually five grams or so which means the total carbs will be higher (maybe close to 40 grams per bar). The protein level will be lower, probably under five grams with around 200 calories per bar.

Other energy bars will also contain close to 200 calories as that seems to be a common thread. Other energy bars may focus more on protein than carbs and contain up to15 grams of protein and less carbs at around 20 grams. Many energy bars average around 5 grams of fat.

In comparison, meal replacement bars are designed to nutritionally replace a low calorie meal of about 200 to 400 calories so this bar is more calorie dense than the other three types. It will usually have 15 to 20 grams of protein, around 30 grams of carbs and five to ten grams of fat. A variety of vitamins and minerals are included as well.

The third type of nutrition bar is the protein bar. A protein bar is an energy bar with the same calories of around 200 or so and 20 grams of carbs but with an extra boost of protein, typically in the range of 15 to 35 grams.

Weight Loss Bars vary from diet plan to diet plan in the nutrition that they contain. They might be high protein, low carb; high fiber, high carb; or more moderate in protein and fat. It all depends on the diet they are designed to go with.