When mingling at a party (or bash), I try to avoid talking about macronutrients. Despite my obvious passion for the subject, chances are people's eyes would glaze over (though they still would prefer it to me talking about cats). Yet you already know a fair amount about macronutrients: carbohydrates ("carbs"), protein, and fat. These help define the types of foods we eat to provide energy for the body.
There are other purposes for macronutrients, such as providing the necessary components for body growth and repair, but the primary purpose of proteins, fats, and carbohydrates (especially fats and carbs) is to provide energy. Energy for the body is measured in calories. While vitamins and minerals (micronutrients) are required in small quantities, macronutrients are needed in large supplies. Our bodies use lots of energy every day (even when we're not particularly active) and we get that energy from food.
Most foods are labeled at a minimum with this breakdown of fats, proteins, and carbohydrates. The total calorie content is simply determined by the weight of each element in the food. Both one gram of protein and one gram of carbohydrates produce approximately 4 calories of energy each while 1 gram of fat produces 9 calories. So a granola bar containing 12 grams of carbohydrates, 8 grams of protein and 2 grams of fat would have an approximate total of 98 calories (12x4 + 8x4 + 2x9). Ain't arithmetic fun?
Since fat has more than twice the calorie content of either carbohydrates or protein, gram for gram, it may suggest the need to avoid fats. However, the balance of macronutrients play an important role in the health and the maintenance of the weight of an individual. Each macronutrient also has other purposes besides providing energy and there are optimal daily amounts of each macronutrient; hence the need for a balanced diet. These optimal daily amounts vary depending on the individual, activity levels, and goals.
Carbohydrates
In addition to providing energy to the body, there are a few specialized uses for carbohydrates. The primary source of energy for the brain comes from carbohydrates. They are used for the construction of organ tissue and nerve cells. Carbohydrates play a pivotal role in maintaining body weight and the right balance of carbs in your diet can help considerably in keeping off excess pounds. A subgroup of carbohydrates known as dietary fiber also aids in the proper functioning of the bowels.
Carbohydrates come in various forms from simple sugars to complex carbohydrates. Of the simple sugars, glucose and fructose are the most well known. These cannot be broken down into simpler sugars and both can be absorbed directly through the intestine walls. Glucose, however, is the form of carbohydrate most used in the body and maintained in the blood. Fructose although a simple sugar cannot be used directly by the body and must first be processed by the liver.
The more complex carbohydrates must be broken down. Some of the common complex carbohydrates are lactose, sucrose, maltose, maltodextrin and starch. They can quickly be broken down by enzymes into simple sugars and then converted to glucose. Compared to proteins and fats, carbohydrates are the fastest source of energy and even the complex carbohydrates can be converted to energy much faster than the two other macronutrients: fats and proteins.
In terms of food sources, carbs come in a number of forms starting with the simple, such as table sugar and high-fructose corn syrup (which seems to be in just about every processed food). Then there are the increasingly complex carbohydrates such as those found in milk, wine, beer (and alcohol in general), vegetables, cereal and grains, and the starchy roots such as potatoes.
Dietary fiber, an important form of carbohydrate, normally consists of the the cellulose of plants, which is indigestible. As mentioned earlier, dietary fiber plays a crucial role in digestion and although it adds bulk to food, it provides very few calories.
Excess carbohydrates are converted to fat and stored in the body.
Proteins
Proteins also have other functions besides providing energy to the body. Proteins are required for growth and tissue repair. This is especially crucial for pregnant women, children, and teenagers (and bodybuilders). In addition, proteins play a pivotal role in the maintenance of the immune system and is used in the production of enzymes and hormones and even hemoglobin. Likewise, proteins are required for cell production and are the major component of many of the body's features, such as nails, hair, tendons, and ligaments. Muscles also are primarily comprised of protein.
Proteins are complex molecules that are made up of smaller building blocks called amino acids. There are 20 amino acids in all. Every protein consists of amino acids that are linked together in various lengths and order. These amino acid chains that make up the protein are either created by the body or are procured from the breakdown of other proteins from the diet. It is useful to note that there are nine amino acids that cannot be synthesized by the body. These are known as the essential amino acids and must be consumed in the form of food in order to maintain health.
Some sources of protein, such as animal proteins, contain all the essential amino acids and therefore are called complete proteins. Proteins from plants, however, must be eaten in combination in order to provide all the essential amino acids. Rice by itself is incomplete. The same applies to beans. However, rice and beans eaten together produce all the essential building blocks for the production of proteins for the body, although in much lower quantity than most meat or dairy products. (Or eggs. It's funny how many people think eggs are "dairy" because they are often found near dairy products in the supermarket.)
Proteins, being complex molecules, take time to digest. As such, the energy released from eating protein takes place over a longer period of time. Foods high in protein are meat, eggs, and fish. Foods with moderate amounts of protein are milk, nuts, and quinoa.
Excess proteins are converted to fat and stored in the body.
Fats
Fats are the most dense form of the macronutrients. As stated previously, it contains more than twice the calories per gram of either proteins or carbohydrates. Fat is also used for other functions including the formation of a protective barrier for the inner organs. And it is used in the production of hormones. Fat is an important part of a balanced diet. The types and amounts of fats consumed, though, can contribute significantly to a person’s health.
Fats, also known as lipids, come in 2 main types, saturated and unsaturated. The unsaturated fats are then sub-categorized in 2 different ways, mono and polyunsaturated and trans and non-trans-fatty. Unfortunately, the people who named these types were interested in the chemical composition of fats and so we have names such as saturated and unsaturated fats, which refer to the status of the hydrogen and carbon bonds in fats. For our purpose, we need to get past the names and understand the benefits and possible harm of each type.
Saturated fats are normally of animal origin, such as butter, cheese and lard. They are solid at room temperature. These fats are used in the production of cell walls and the formation of various hormones. Eaten to excess though, saturated fats can raise the cholesterol level in the blood.
Unsaturated fats are liquid at room temperature and come in two forms, monounsaturated and polyunsaturated and both are generally considered a better source of fats and much healthier for the heart. Examples of monounsaturated fats are olive, peanut and canola oil. Polyunsaturated examples are corn and safflower oils and are found in fatty fish, such as salmon, herring and mackerel. Polyunsaturated fat are further subdivided into the omega 3 and omega 6 families of oils.
Along a completely different line, unsaturated fats can come in two different structures, straight and bent. The bent form is known as trans fatty acids which are considered bad for the body. These forms are generally found in processed foods to give them shelf life and special characteristics and textures (such as spread ability). Partially hydrogenated vegetable oils are prime examples of such processed food. The process of hydrogenation is used to make these liquid oils into solids. Margarine, commercial baked goods (donuts!), and many fried foods have been known to contain these trans fatty acids which are considered harmful and contribute to heart disease. In fact, they're so bad, they're being legislated away. Yay!
While macronutrients may not be the most exciting topic you'll read about, it may be one of the most useful to understand. But you might want to to avoid talking about them at parties.