Final answer:
Plant-based protein sources typically offer less protein per 100 grams compared to animal-based sources. Rice protein, specifically, is often cited as being low in the essential amino acid lysine, indicating a lower protein density. Therefore, plant proteins like rice are among the protein sources with the lowest density of essential amino acids.
Step-by-step explanation:
When considering which protein source offers the least protein per 100 grams, we must look at the density of essential amino acids in various dietary proteins. Since proteins are composed of amino acids and different foods offer varying amounts of these, the protein content can also vary widely. Generally, plant-based proteins are thought to have lower protein content than animal-based proteins. For example, rice protein is alluded to as being low in the amino acid lysine, making it less protein-dense, and therefore it is often combined with other proteins to improve its amino acid profile.
Among animal proteins, insects are a source of protein in many parts of the world and can vary greatly in protein content. However, insects may not be as commonly consumed or accessible as other protein sources globally. On the other hand, plant foods like legumes and grains are common sources that may offer less protein per 100 grams compared to most animal-derived foods.
Protein sources such as meat, fish, and eggs are known to be complete proteins, providing all essential amino acids in adequate amounts, whereas many plant proteins are classified as incomplete proteins and may lack one or more essential amino acids. Therefore, it is generally the case that plant-based protein sources will offer the least amount of protein per 100 grams compared to animal-based protein sources.