The 3 Macronutrients
CARBOHYDRATES
Carbohydrates get a bad wrap. There are a lot of diets out there that restrict carb intake. But here's the thing about carbs: THEY ARE NOT THE ENEMY. Your body needs carbs for immediate fuel. In the absence of carbs, your body has to create them from non-carbohydrate sources (which is sort of the theory behind carb restricted diets, like Keto) but this isn't the best or most efficient way to fuel your body. The brain requires glucose to function and will do whatever it takes to make glucose from non glucose sources. The presence of adequate carbohydrates can spare the body’s need to catabolize (break down) muscle tissue. You worked so hard to build lean muscle tissue. Don't force your body to break this tissue down because you are not giving it carbs.
Fiber is also a carbohydrate. There are two types of fiber. Soluble and Insoluble. Both can aid weight loss, enhance digestive health, and reduce cancer risks. Fiber is an important part of our diet, and most people do not get enough daily. Daily recommended intakes are 38g for men and 25g for women.
Carbohydrates are 4 calories per gram. This is the macronutrient most affected by training volume. As intensity/duration of workouts increases, your body will need more carbohydrates.
FATS
Fats have several functions in the human body. They provide heat insulation, aid in the digestion of fat soluble vitamins (A, D, E, and K), help to regulate hormones, and provide energy to the body.
There are several different types of fats you may have heard of, including Omega-3's, Omega-6's, saturated, unsaturated, cholesterol, and triglycerides. However, you may not know the differences between them or which ones our body needs and which ones can be harmful in larger quantities.
Let's start with saturated fats. Saturated fats are usually solid at room temperature. They are mostly found in animal products such as butter, cheese, and meat as well as coconut oil, and margarine. According to the "Dietary Guidelines for Americans", saturated fats should be limited to 10% of total calories per day.
Unsaturated fats are typically liquid at room temperature, and are chemically more unstable than saturated fats. These are found primarily in plant sources such as nuts, avocados, olives, and flax. These are part of a heart healthy diet, and you will see these foods feature prominently in the Mediterranean Diet. Current guidelines are currently set at consuming 20%-35% of daily calories in fats, preferably polyunsaturated fats, as these encompass Omega-3 and Omega-6 fatty acids.
Omega-3 Fatty acids are not produced by the body and must be obtained in the diet. They have anti-inflammatory properties and may help decrease the risk of developing cardiovascular disease. Research is also going in to possible benefits for lowering depression and protecting against Alzheimer's and dementia. Omega-3 fatty acids can be found in cold water fatty fish and shellfish, as well as chia seeds and flaxseed oil. Most people do not get enough of these in their diet.
Omega-6 fatty acids are also derived from the food we eat as they are not synthesized in the body. These can be found in nuts and seeds such as walnuts, pecans, sesame seeds, and sunflower seeds. A large number of processed foods also contain Omega-6 fatty acids, as they contain canola oil or soybean oil. Especially in the western diet, there is an excessive intake of omega-6 fatty acids, and not enough omega-3 fatty acids.
Fats contain 9 calories per gram, making them the most energy dense of the macronutrients. The best sources for fats in the diet include dairy, nuts, seeds, fish, and some oils.
PROTEIN
All proteins are made up of amino acids. Out of the hundreds of amino acids in nature, there are just 20 that the body needs to perform its various functions. 9 of these cannot be synthesized in the body and must be obtained through the diet. These are the Essential Amino Acids.
When protein is consumed, it is first broken down into amino acids and absorbed by the body. From here they can be recombined to form new proteins such as collagen, elastin, keratin and hemoglobin. The process by which amino acids are joined together to form proteins such as lean tissue (muscle) is called protein synthesis. The human body is constantly forming and breaking down proteins simultaneously. Protein synthesis is an anabolic reaction and protein breakdown is a catabolic reaction.
The maximum amount of protein that can be absorbed in one meal is not yet determined. 85% of plant protein is absorbed, and 95% of animal protein is absorbed. Unlike carbohydrates and fats, there is no storage system for excess protein in the body. It is used to make muscles and bones. Protein is not a primary source of energy like carbohydrates and fats, but rather a structural and functional macronutrient.
Protein contains 4 calories per gram, like carbohydrates. The RDA for protein is .8g per kg of bodyweight. This number, really depends on the individual--their body composition, activity level, and goals. People typically need between .8-2.2 g per kg of bodyweight per day. More protein is needed for active individuals than sedentary ones, and more is required for recovery from strength training than from cardio/endurance training.