Written by As I noted in my previous post, I am starting a new series on this blog pertaining to our health and how to optimize it through understanding what we eat. If you missed my last post, you can view it here. In order to fully understand some of the other important concepts relative to nutrition, we must first understand how different diets are generally broken down. The are three macro-nutrients commonly referred to in most diets- carbohydrates, protein, and fat. In general, 100% of your daily intake of food is a combination of these three things. The percentage of each that a person eats can vary depending on his/her diet. One thing that I consider to be crucial to understanding how to be healthy, is the role of our metabolism, and how different variations of the macro-nutrients can effect how our metabolism operates. Here is the nitty-gritty science of it all- most of which I have grabbed from handy sites such as Wikipedia (no sense in re-inventing the wheel here).
- In food science and in many informal contexts, the term carbohydrate often means any food that is particularly rich in starch (such as cereals, bread and pasta) or sugar (such as candy, jams and desserts). There are simple carbohydrates such as white bread, pasta, and candy and there are complex carbs which are generally whole-grain products and things like vegetables. Carbohydrates are a superior short-term fuel for organisms because they are simpler to metabolize than fats or those amino acid portions of proteins that are used for fuel. The most important carbohydrate for animals is glucose; so much so, that the level of glucose is used as the main control for the central metabolic hormone, insulin. Insulin is a hormone that is central to regulating energy and glucose metabolism in the body. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle. See Wikipedia if you want to learn more about this. Note: while insulin comes into play during times when our blood sugar is raised, Glucagon performs the opposite function: it will raise our blood sugar levels when they are too low. Insulin stops the use of fat as an energy source (and therefore during times of Glucagon use, our bodies utilize fat as an energy source). It stands to reason then, that too many carbohydrates equates to a constant elevated level of blood sugar, which in turn tells the body to provide a constant supply of insulin. If we are always utilizing insulin, then we are never using fat as our energy source. However, when insulin is absent, glucose is not taken up by body cells and the body begins to use fat as an energy source, for example, by transfer of lipids from adipose tissue to the liver for mobilization as an energy source. There are 4 calories in one gram of carbohydrate. Based on the effects on risk of heart disease and obesity, the Institute of Medicine recommends that American and Canadian adults get between 45–65% of dietary energy from carbohydrates. The Food and Agriculture Organization and World Health Organization jointly recommend that national dietary guidelines set a goal of 55–75% of total energy from carbohydrates, but only 10% directly from sugars (their term for simple carbohydrates).
- Protein is essential to the human body, providing the building blocks of muscle and tissue synthesis. Proteins are broken down in the stomach during digestion by enzymes known as proteases into smaller polypeptides to provide amino acids for the organism, including the essential amino acids that the organism cannot biosynthesize itself. The indispensable amino acids are leucine, isoleucine, valine, lysine, threonine, tryptophan, methionine, phenylalanine and histidine. Most animal sources and certain vegetable sources have the complete complement of all the essential amino acids in adequate proportions. Unlike carbohydrates, protein has almost no effect on blood sugar levels, therefore, it does not contribute to elevated insulin levels in the body like carbohydrate do. There are 4 calories in one gram of protein. According to US & Canadian Dietary Reference Intake guidelines, women aged 19–70 need to consume 46 grams of protein per day, while men aged 19–70 need to consume 56 grams of protein per day to avoid a deficiency. Several studies have concluded that active people and athletes may require elevated protein intake- as much as 1-2 grams per pound of lean body mass (muscle).
- Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. Chemically, fats are generally triesters of glycerol and fatty acids. Fats may be either solid or liquid at room temperature, depending on their structure and composition. Although the words “oils”, “fats”, and “lipids” are all used to refer to fats, “oils” is usually used to refer to fats that are liquids at normal room temperature, while “fats” is usually used to refer to fats that are solids at normal room temperature. “Lipids” is used to refer to both liquid and solid fats, along with other related substances. Fats form a category of lipid, distinguished from other lipids by their chemical structure and physical properties. This category of molecules is important for many forms of life, serving both structural and metabolic functions. They are an important part of the diet for humans. Fats or lipids are broken down in the body by enzymes called lipases produced in the pancreas. Vitamins A, D, E, and K are fat-soluble, meaning they can only be digested, absorbed, and transported in conjunction with fats. Fats are also sources of essential fatty acids, an important dietary requirement. Fats play a vital role in maintaining healthy skin and hair, insulating body organs against shock, maintaining body temperature, and promoting healthy cell function. Fats also serve as energy stores for the body, containing about 9 Calories per gram of fat. They are broken down in the body to release glycerol and free fatty acids. The glycerol can be converted to glucose by the liver and thus used as a source of energy. In general, it recommended that fat not exceed 30% of your daily calories. Often, less than 25% is recommended. Remember there are good and bad fats… generally speaking just stay away from anything that is saturated fat or contains trans-fatty acids and you’ll be okay.
Now that we have that out of the way, one important take away from this is that carbohydrates are the primary effectors of the insulin levels in your bloodstream. The more of them you eat, the more insulin your body needs. Note: there are ways to keep this in check, such as eating fat or protein along with your carbs). The other important message here is that carbs are not essential nutrients in humans: the body can obtain all its energy from protein and fats. The brain and neurons generally cannot burn fat for energy, but can use glucose or ketones; the body can also synthesize some glucose from a few of the amino acids in protein and also from the glycerol backbone in triglycerides. Current guidelines for food sources suggest that carbohydrates make up the majority of our diet… while that works for some, it doesn’t work for everyone. If this macro-nutrient is not essential, then we can control how much we consume without any threat to our health (and likely the opposite will occur- improved health). I happen to believe that the modern-day carbohydrate recommendations are too high. Americans eat too many of them, keeping their blood sugar continuously elevated. We end up with continually elevated levels of insulin in the bloodstream to bring glucose levels down, and ultimately storing, rather than burning, fat.
Insulin levels in the body cause more problems than just diabetes. Too much insulin in the body will result in insulin resistance (a precursor to diabetes), a physiological condition where insulin becomes less effective at lowering blood sugars. The resulting increase in blood glucose may raise levels outside the normal range and cause adverse health effects. In an insulin-resistant person, normal levels of insulin do not have the same effect in controlling blood glucose levels. During the compensated phase on insulin resistance insulin levels are higher, and blood glucose levels are still maintained. The elevated insulin levels have additional effects that cause further abnormal biological effects throughout the body including high blood pressure, heart disease, obesity, excess fluid retention, elevated blood fats, and other degenerative diseases.
The first thing each of us should look at is how much of each macro-nutrient do we eat each day? Are we carb junkies? If so, what kind of carbs are we eating- simple or complex? How much protein are we getting, and is it all coming from animal products, or does some of it come from healthy vegetable, nuts, and seeds? Ask yourself the same question about the fats in your diet. One of the biggest fallacies in the American diet is that fat is bad. The fat that is clogging your arteries is not coming from the fat in your diet. It’s coming from the excess glucose being stored as fat because insulin levels are too high.
Most of us eat too much sugar. When I say sugar, I don’t just mean candy and cookies. I am talking about the sugars in your bread, your baked beans, your fruit salad, your salad dressing, crackers, and everything else. Keep track, and look at the carton/box of everything you eat. You’ll be surprised at how much hidden sugar there is in the food we eat. I would say that most Americans are likely consuming too much carbohydrates, too many of the bad fats, and too little protein.
Macro-nutrient breakdowns are going to be specific for everyone. I typically consider a healthy range of carbohydrates to around 30%, protein around 40% and fat around 30%. More than 30% carbohydrates and I believe the body is robbed of protein it needs and flooded with insulin it doesn’t. The trick is knowing what to get your carbs, protein, and fats from! They are not all created equal. We will dive into this in the next post, Organic vs. Conventional foods, and Grain-fed vs. Grass finished. Here are some links to additional resources for understanding macro-nutrients.
- Wikipedia has a list of macro-nutrients further broken down for additional information.
- Here’s a great calculator which shows many different schools of thought for macro-nutrient percentages.
- Here’s another macro-nutrient summary.
Recent Comments