All of the food we eat is composed of three basic macros. They are proteins, fats and carbs. All three macros are composed of a carbon back bone, which provides energy, and various molecular side chains, which differentiate the macros from one another. These side chains also determine how the body digests, absorbs and processes the food. It is therefore not enough to just count energy or calories when we eat food. The ratios of macros must be considered, because each of the macros will have a very different effect on the body. For simplicity, the three macros will be discussed individually. However, it is important to note that most foods are composed of some combination of all three macros.
Basics: Proteins have many functions in the body. They help build muscle, the immune system, cell membranes, genetic code, hormones, cells structure, messenger molecules and much more. Protein is primarily found in animal products, although, some plant sources are available.
Structure: The basic unit of protein in known as an amino acid. When many amino acids are combined together, they create a protein.
There are 20 amino acids including: leucine, tyrosine, glycine, tryptophan, proline etc.
Examples: Red meat, fish, eggs, tofu poultry etc. all contain high amounts of protein.
Essentials: There are 9 essential amino acids. These amino acids cannot be created by the body; they must be consumed in the diet.
Digestion and absorption:When protein is consumed, it is broken down into amino acids by the stomach acid. In the small intestine the amino acids are then absorbed into the bloodstream. Once in the blood, they travel to the liver. The liver then shuttles the amino acids to other tissue which require building and repair. If excess protein is consumed, it is recycled by the liver and the carbon backbone is converted into glucose or ketones.
Energy: Protein generates 4kCal per gram
Basics: Fats have many functions in the body and can serve as energy. Fats are required for building cell structure, cellular messaging, hormone production, micronutrient absorption etc. Fats are found in both plant and animal products.
Structure: Fatty acids can be divided into 2 groups: saturated and unsaturated.
Saturated fatty acids are primarily found in animal products, are solid at room temperatures and are less likely to rancidify. This means that they are more shelf and heat stable.
Unsaturated fatty acids are liquid at room temperature and can differ in degree and location of saturation. Monounsaturated fats have only one unsaturated bond. Polyunsaturated fats have more than one unsaturated bond.
Unsaturated fatty acids which are chemically saturated (to help preserve or solidify the fat) are known as trans fatty acids.
When combined together fatty acids can form triglycerides and phospholipids. Triglycerides are the main form of excess energy storage.
Phospholipids help carry out essential processes in the body.
Examples: Butter, lard and coconut oil, are all examples of saturated fats. Olive oil is an example of a monounsaturated fat. Canola and vegetable oil are polyunsaturated fats.
Essentials: There are 2 essential fatty acids. They are omega 3 and omega 6 fatty acids. The number indicates the location of the unsaturated bond.
Digestion and absorption: When fat enters the body, it is broken down and absorbed in the small intestine. Unlike the other macros, which enter the blood, fat is combined into a molecule called a lipoprotein and enters the lymph, bypassing the liver.The fatty acids are distributed to the body. The leftovers make it into the blood and are taken up by the liver for further processing.
Energy: Fat generates 9kCal per gram
Basics: The sole purpose of carbs is to provide energy. Most carbs come from plants.
Structure: Carbs can be divided into 2 groups: simple and complex
Simple carbs include monosaccharides and disaccharides.
Monosaccharides are single unites. They are: glucose, fructose and galactose
Disaccharides are pairs of monosaccharides. They are: Lactose (galactose + glucose) maltose (glucose + glucose) and sucrose (glucose + fructose).
Complex carbs are polysaccharides and include starches, cellulose, gums, pectins etc. These are long chains composed of a combination of simple carb units. Only starches can be fully digested and absorbed by humans. When found in food, the rest of the polysaccharides are collectively called fibre.
Examples: Table sugar, high fructose corn syrup, honey, milk, fruit/juice, pasta, vegetables, rice, bread, pastries, pop, cereals etc.
Essentials: Unlike the other two macronutrients, there are no essential carbohydrates. Therefore decreasing carbohydrate intake does not directly lead to any deficiencies.
Digestion and absorption: When carbs are consumed they begin digestion in the mouth and end in the small intestine where they are also absorbed into the blood. Once in the blood each monosaccharide is processed differently.
Glucose raises blood sugar and immediately requires insulin to be taken up by the fat cells.
Fructose can only be processed by the liver. The liver directly converts fructose into triglycerides for storage. Excess fructose is the main cause of non alcoholic fatty liver.
Galactose is also only processed by the liver, where it is converted into glucose.
Excess glucose and galactose leads to insulin resistance an eventually type 2 diabetes
Energy: Carbs generates 4kCal per gram