Protein: the Macronutrient
Proteins play many roles in the body, from structural support, to acid-base and fluid balance, to enzyme and hormone creation. When we consume proteins in the diet, they enter the body and break down to amino acids which are then absorbed by the blood supply to be used. Dietary protein improves satiety and appetite control in the body. Eating a meal balanced with a good source of protein will leave you satisifed with that feeling of fullness for longer.
Not all Proteins Are Created Equal
The digestability and amino acid profile vary in protein sources. Generally speaking, animal proteins are more digestable (95-99% of protein molecules eaten are absorbed) than plant based proteins (70-90% of protein molecules consumed are absorbed). In terms of amino acid profile; there are 9 essential amino acids (our bodies don't make these, we need to eat them) and 11 non-essential amino acids (we can synthesize these). A protein that contains all 9 essential amino acids and some non-essential amino acids is considered a complete protein.
Complete proteins: animal meats (red meat, poultry, fish), soy products, quinoa, eggs
Incomplete proteins: vegetables, beans, nuts, nut butters, grain products, dairy *This is why incorporating complementing protein sources is important in vegetarian diets to create a complete protein, for example eating rice and beans together.
In the United States, protein is often overconsumed (men average >100 grams daily and women >70 grams daily). The recommendation for adults is 0.8 g/kg/day. This increases with physical activity levels (usually up to about 1.3-1.5 g/kg/day for athletes). Consuming a well-balanced diet usually meets daily protein needs.
Striking the right balance in protein consumption is important. Protein is essential to many bodily functions and plays an improtant role in hunger and satiety. On the other hand, a high-protein diet can increase the risk of heart disease, kidney problems, and calcium loss from bone. Consuming too much protein from animal sources usually causes an increase in saturated fat consumption, which leads to high cholesterol and heart disease.
Overall, balancing protein sources at meals with whole grains, dairy, fruits, and vegetables is important.