I always say that the term “healthy diet” is a political term. After all, the USDA Food Pyramid is nothing but politics. Whoever lobbies the hardest, or pumps the most research into biased “scientific” studies gets their desired place on the pyramid. Of course, things are getting better (in my opinion), in regard to the pyramid, but we still have a long way to go when it comes to promoting quality and strategy.
Without going into another rant about denatured “bastardized” foods available on the market, I’d like to write about the roles of macronutrients in the diet, and how they should be a part of every meal.
A macronutrient is an essential substance required in relatively large amounts by a living organism. A micronutrient, on the other hand, is a substance required in relatively small amounts–like vitamins and minerals.
What qualifies as a human macronutrient varies according to who’s talking about it, but the list looks something like this: fat, carbohydrates, protein, fiber, and water. In this article, I will focus mostly on the first three. By focusing your attention on the first four, and eating them from quality sources, as few people need a better understanding of water.
Fats/lipids are a group of compounds that are generally soluble in organic solvents and generally insoluble in water. The include triglycerides, phospholipids, and sterols. In the diet, 95% of lipids are fats and oils (in the body, 99% of stored lipids are triglycerides, that is, three fatty acids attached to a glycerol backbone.
Fatty acids come in three forms: saturated, monounsaturated, and polyunsaturated. These levels of “saturation” are determined by how many hydrogen atoms are attached to the chain of a particular fat–and chains vary in length as well.
No need to concern yourself with the chemistry. Think of it this way: saturated fats are solid at room temperature, unsaturated fats are liquid. Keep it simple.
Lipids are the most concentrated source of energy, packing 9 calories per gram (because of this, many people try to avoid fat in order to lose weight, since it is easy to overeat on certain types of fat). Fats are involved in the following:
- Cellular membrane structure and function
- Precursors to hormones
- Surrounding, holding, and protecting organs
- Regulation and secretion of nutrients in cells
- Insulating the body from environmental temperatures and preserving body heat
- Initiating the release of the hormone cholecystokinin (CCK), which contributes to feelings of satiety*
- Prolonging the digestive process by slowing the stomach’s secretion of hydrochloric acid*
*Fat is digested and absorbed quite slowly (by without great digestive effort), and therefore remains in the stomach longer than carbohydrates or proteins. For this reason, it leaves you feeling fuller, longer. When you eat fat, it’s like throwing a big log on the fire–it is slow to burn, and gives you hours of lasting, consistent heat (energy).
Proteins are polymer chains of amino acids linked together by peptide bonds. They must be broken down into their separate amino acids before the body can make use of them. Of the 20 essential and nonessential amino acids, only 8 essential amino acids (ones the body cannot make on its own) are necessarily derived from the diet.
A “complete” protein is any protein source that contains all 8 essential amino acids. Animal sources of protein are complete–plant sources are often incomplete (or low) in some amino acids.
Amino acids from protein are needed for the following:
- Synthesizing body-tissue protein
- Providing glucose for energy (if needed)
- Contributing to fat stores (not always)
- There is not enough available energy from carbohydrate or fat
- If essential amino acids are lacking or consistently too low
- There is an excess of too much necessary protein (and they will be excreted from the body instead)
- Calcium depletion
- Fluid imbalance
- Slower metabolism (due to insufficient fat and carbohydrates)
- Energy loss
With each meal, be sure to have a variety of foods, to ensure sufficient amino acid consumption.
- It provides bulk in the diet, thus increasing satiety (some fibers delay the emptying of the stomach, subduing a potent hunger hormone, ghrelin)
- Prevents constipation
- Maintains good intestinal mobility
- Aids in prevention of bacterial infections
- Reduces risk for heart disease by lowering blood cholesterol (certain fibers bind with cholesterol compounds and sweep them out of the body; may also inhibit production of bad cholesterol)
- Regulates body’s absorption of glucose (sugar)
Every meal should be eaten in balance. Carbohydrates, fat, and protein should be eaten with every meal. This ensures slow, consistent digestion and energy throughout the day. Carbohydrates should not be avoided, as they are the body’s primary fuel source. Avoid carbohydrates that have been stripped of their fiber. Fat should accompany the meal, to slow the digestive process and increase levels of satiety. Protein is present in most foods, but it is important to eat a variety of foods, so that all essential amino acids can be obtained (as well as vitamins and minerals).