Macronutrients
Macronutrients are abundant in food and they were discovered very early on by scientists. They can be used for energy. With enough supply of food, it is impossible to be deficient in macronutrients.
Carbohydrates
Carbohydrates are the result of photosynthesis so they are mostly found in plant foods. They provide the body as its main source of energy. The brain can only utilize glucose so it is critical for the body to maintain a steady level of blood glucose by storing enough carbohydrates and releasing them over time.
Carbohydrates can be further divided into simple carbohydrates and complex carbohydrates. Simple carbohydrates are also know as sugars. They are the sweetness we usually taste in food. We have a natural craving for sweetness because they usually signal the presence of carbohydrates which the body needs for survival. However, simple carbohydrates are absorbed too quickly in the body and can cause a spike in blood glucose level which over a long time can lead to metabolic illnesses such as diabetes. American currently consume way too much sugar and mostly from drinks like soda.
Complex carbohydrates are long-chained sugars. They take a long time to break down and provide the body with a steady supply of glucose. Therefore ingesting complex carbohydrates is much preferred over simple carbohydrates. Complex carbohydrates are usually found in grains as well as starchy food.
Fats
Fats are a caloric-denser form of energy storage than carbohydrate. They are not as common as carbohydrates in nature, so people have an instinct to seek them. Fats also have other properties that makes them attractive. Flavor of foods are mostly in the form of volatile oils. Therefore they are best released by dissolving in fats. So adding fats makes food more flavorful.
Another property of fat is that they allow a higher cooking temperature, such as frying and stir-frying. At high cooking temperature, food will undergo a process known as browning effect, which makes the flavor more complex and intense. Cooks in both East and West have known the properties of fats in food and have used them extensively in cooking. As a result, restaurants and processed foods will contain much more fat than home-cooked meals. Since Americans eat very little home-cooked meals, most people eat way too much fats.
Fats can be further classified into saturated and unsaturated fats. Basically unsaturated fats have at least one double bond. This chemical structure makes unsaturated fats less dense and less viscous than saturated fats. The more viscous saturated fat are more likely to clog your blood vessels and cause cardiovascular disorders. So not only do people need to reduce total fat intake, they should also avoid eating saturated fats.
Proteins
Proteins is scarce in nature because protein contains nitrogen, and nitrogen fixing is energy intensive. The scarcity of protein means people must actively look for it, suggesting people have a built-in desire for protein. It is the savory taste in a “good”, heavy meal that people look for. Historically, and currently in poor countries, protein deficiency is a very real danger. However, employing nitrogen-rich fertilizers, we are able to produce unimagined abundance in food. Now not only were we not in risk of protein deficiency, we are actually in risk of over-consuming protein.
What is worse is our society has developed a fascination with protein. We have an overkill mentality in America. People are always looking for the car with the most horsepower. People are buying professional stove and cookware despite the fact that as a society we cook very little home-cooked meal. A subset of our society is in danger of overeating proteins due to the mistaken believe that this is the single most important indicator of nutrition. Such false notion was imprinted by early scientists because they saw the relative rarity of protein and its function as the body’s building block. However, the body cannot store protein. Excessive protein intake is not only unnecessary, the body must actively eliminate them, putting unnecessary burden on the body.
Traditionally protein are classified according to their rate of absorption. “High quality” proteins, similar to human body’s composition, are absorbed faster. They come mostly from animal source. “Low quality” proteins, on the other hand, unlike human body and are absorbed slower. Early scientists assumed that faster absorption is better but that was never proven. It may very well be that like carbohydrate, slower absorption is preferred.
Another danger of high protein diet is that some proteins may not break down completely into amino acids during digestion. They may enter the body as peptides. Peptides are small protein chunks. They have wide range of bodily functions. Some peptides act as neurotransmitters by stimulating neurons. Some act as immune signals. Ingesting large amount of protein may trigger unknown immunological and neurological effects. Early studies have shown the connection of diet to brain scans as well as autoimmune diseases. Therefore people should limit their protein intake to adequately cover their daily need.