For illustrative purposes, let us take apart an example recipe. The recipe is a generic 2,000-calorie recipe, based on the DRI standards. It may be found here. Let us break down the ingredients:
150g waxy maize starch.
A source of carbohydrates. WMS is a low GI, easily digestible carbohydrate.
A source of carbohydrates. Maltodextrin is a moderately high GI carbohydrate which is inexpensive, is slightly sweet, and dissolves completely in water. The reason we use a mix of maltodextrin and WMS is to provide relatively immediate energy (from the maltodextrin) followed by slow-burning energy (from the WMS). It also reduces the cost a bit.
10g whey protein isolate.
The primary source of protein. Whey protein has a complete amino acid profile; it is a good source of all essential amino acids.
60ml canola oil.
The primary source of fat. It has a good fat profile, being mostly unsaturated and providing adequate amounts of omega-3 fatty acids.
The primary source of soluble fiber. Dextrin is tasteless and dissolves completely in water.
The primary source of insoluble fiber.
Lecithin plays several important roles. It is an emulsifier, which means that it keeps the mix from separating. It is a source of phosphorus, and the primary source of choline. It is also a source of fat.
2 pills Optimum Nutrition Opti-Women Multivitamin.
The multivitamin serves to provide adequate amounts of all vitamins except choline, and many minerals.
20g potassium gluconate.
A source of potassium. Like gluconates in general, potassium gluconate is an especially well-absorbed form of potassium.
8g magnesium gluconate.
A source of magnesium.
1g calcium phosphate.
A source of calcium and phosphate.
1g calcium carbonate.
A source of calcium.
Salt, being sodium chloride, is a source of sodium and chloride.
This recipe does not contain any flavorings. One flavoring option would be to add 1tsp cinnamon and 1tsp vanilla. Another option would be to add 20g cocoa powder.