Macronutrients Guide - Dietary Facts About Carbohydrates Protein & Fat

There is almost too much information spinning around on the subject of nutrition, mainly because of the amount of 'diet experts' that perpetuate the world of marketing. Cutting through all of this information and misinformation can be challenging at best. In this article, you will learn foundational nutritional information as well as some specific techniques you can use to help keep you lean and healthy. This article will attempt to align with current food labeling information as well to stay understandable.

For the purpose of this article, we will define a macronutrient as one of a group of food chemical compounds that we as humans consume to provide the bulk of our energy - specifically carbohydrates, proteins, and fats. Understanding the relationship between these macronutrients as well as how the body processes them can give you a big advantage in the quest toward a healthier you. Let's start with carbohydrates.

Carbohydrates
A carbohydrate is just a sugar on a fundamental level. In fact, the word monosaccharide can be literally translated as single sugar. Carbohydrates in nutrition are all types of sugars, and while 'sugar' has earned a bad rep in the health and nutrition circles, it is important to understand that carbohydrates all fit in this classification. How they are structured and how your body processes them changes the impact different saccharides may have on your body, however.

The three main types of carbohydrates to be concerned about are monosaccharides, disaccharides, and polysaccharides. Literally translated, the prefix mono is single, di is double, and poly is many. So a polysaccharide is technically nothing more than a clump of monosaccharides. And a disaccharide is nothing more than two monosaccharides combined together.

Why is this important? Well, you can break the category of carbohydrates down into a more global separation to match with nutritional labels by using the terms simple sugar (mono- or disaccharide) and complex carbohydrate (polysaccharide). It is also important because of the way your body digests carbohydrates.

As food is being digested, your body is looking to break whatever food comes into the digestive system down by reducing it into very manageable blocks. In the case of carbohydrates, your body breaks them down into a simple sugar called glucose (otherwise known as blood sugar). Glucose will be stored in your muscle tissue and liver and held as stored energy (called glycogen). Glucose is also primarily used by your brain - if you've ever noticed how your energy levels can drop after spending a lot of time thinking, this shows you how much blood sugar that computer in your head can eat up. (Interestingly enough, glucose is a monosaccharide and glycogen is a polysaccharide. Glycogen will be broken down into glucose as needed and is stored to keep blood sugar levels relatively steady.)

So if you eat two different carbohydrates, let's say one is table sugar (sucrose, a disaccharide) and the other is a potato (a polysaccharide otherwise known as starch), your body will go to work digesting them. The table sugar is snapped in two and converted over to glucose relatively quickly. After all, there isn't much to do - just break the thing in half, pretty much. The starch, on the other hand, is more of a tangled mess as it consists of multiple glucose molecules jammed together. This takes your body a bit longer to break apart (think of taking confetti off of flypaper). Here's what this means to you: the simple carbohydrate is digested quickly and hits your blood stream rapidly, while the complex carbohydrate takes a bit longer to digest and consequently the glucose molecules are more steadily released into your bloodstream, not to mention the benefit of vitamins and minerals from the potato that the table sugar is lacking.

All of this relates to terms like glycemic index and glycemic load. The nugget of wisdom to get out of all of this is the same kind of things that you've heard before: eat more complex carbohydrates than simple carbohydrates (also referred to as simple sugars).

If we look at the thermic effect of carbohydrates, because it takes energy to digest the very food that is used to obtain energy, it is estimated that carbohydrates will take away about 10% of their calorie value through the digestive process. So, if you ate 50 calories of complex carbohydrates, your body would spend about 5 calories breaking down that carbohydrate into useable glucose. This figure may become more significant as we look at the other macronutrients.

Special Note: While dietary fiber is categorized under the carbohydrate section of nutritional labels, it is technically indigestible by humans as dietary fiber is a non-starch polysaccharide. Fiber is primarily used by the body to absorb toxins and help push food through the digestive system. Fiber is a crucial part of healthy dietary nutrition - look for good sources of both soluble and insoluble fiber.

Fats
One of the most interesting things about fats is the fact that just because you ingest fat doesn't mean that you will end up being fat. Fats are a critical part of healthy dietary intake and are utilized within the body for a variety of purposes, some of which include health of cell walls, storing/transferring fat-soluble vitamins, skin and hair health, and providing energy for your body. Like carbohydrates, there are different types of fats that the body can use.

Saturated fat gets a lot of bad press, like sugar above, and is found primarily in animal meats as well as some oils (coconut, cottonseed, palm kernel, etc.). It is important to note that not all fats labeled as saturate fats are the same. There is a fundamental difference in the fatty acid ratios between coconut oil and butter, for example.

Monounsaturated and polyunsaturated fats tends to be liquids at room temperature, due to the nature of the chemical bonds that prevent them from easily being 'stacked' on top of one another. You can think of saturated fat as a straight wire and polyunsaturated fats more like steel wool. If you try to stack a couple of wires on top of one another, you can make a pretty dense little metal structure. If you try and mash steel wool into the same kind of shape, it will spring back and refuse to flatten out.

However, these polyunsaturated fats can be chemically straightened by changing the nature of the bond in the fats. Chemically speaking, the double bond that is in a formation called 'cis' is changed to 'trans'. This takes some of the bends out of the unsaturated fat and allows it to better stack against itself. So much so, in fact, that you can force this chemically treated oil to become somewhat solid at room temperature. Thus we have 'trans fat' which was originally marketed as margarine, ironically labeled a 'healthier alternative to butter.' I tend to stick with the Nature Knows Best philosophy with food, even though I have a chemistry degree.

So, if eating fat doesn't necessarily make you fat, then what do you need to know about it? You should first know that fats help make you feel full. They are packed with energy - over twice that of carbohydrates and proteins on average - and should not be the mainstay of your nutritional uptake, but are very important nonetheless. In a meal of mixed macronutrients, a recommended manner of eating, fats will help to slow down the absorption of foods with a higher glycemic index. This will help the energy from carbohydrates be more evenly distributed into the bloodstream, preventing blood sugar spikes and corresponding fat storage responses in your body. Fats also help you feel full, so if eating a healthy slower pace, your body should send signals of fullness earlier than if eating just carbohydrates, for example.

The thermic effect of fats is depressed from other foods - if carbohydrates were somewhere around a 10% thermic effect, fats are sitting in at 5% or less. In essence, fats are long chains of molecules. In order to digest these chains, your body just goes along snipping them into smaller chains. This doesn't take as much work as breaking apart the component sugar molecules of carbohydrates, for example.

With fats, it's a good idea to stick with mono- and polyunsaturated fat sources as the primary source of fat in your dietary intake. Foods that are rich in omega-3 (and omega-9) fatty acids are a good bet, and stay away from foods that use trans fats. Remember - you can turn a good fat into a trans fat if you cook it at high enough temperature - become knowledgeable about the heat sensitivity of different oils that you may be cooking with.

Proteins
If you get down to the meat of it all, proteins are another critical building block of a healthy dietary intake. In fact, meats are one of the main sources of proteins, although different vegetables will have them as well. Proteins are essentially tangles of amino acid molecules. There are twenty different types of nutritional amino acids, some of which are labeled as 'essential amino acids' because our bodies cannot produce them on their own - we must get them from our nutritional intake.

If a protein contains all of the essential amino acids, it is considered a 'complete' protein. An incomplete protein is therefore a protein that does not contain all of the essential amino acids. Does this mean that incomplete proteins are bad? Of course not. In fact, many vegetables fit into this category and by eating two vegetables that compliment the 'missing' amino acids in each other's profile, your dietary intake will then have a complete amino acid profile.

Proteins are used in our cells for a variety of functions. One of the more publicized functions is the building of muscle tissue. Without proper protein intake, your body will be unable to maintain all of those tiny muscle fibers that make up your muscles which keep you strong, toned, muscular, etc. So protein is a pretty important macronutrient when it comes to staying lean and healthy. After all, if our base metabolism is primarily determined by how much living tissue we have in our bodies (muscle, bone, etc.), then we might as well keep as much as we reasonably can.

The thermic food effect of proteins is a little different than fats and carbohydrates. Remember how proteins are a tangled knot of amino acids? Well it takes a lot more work to break these things down for your body to use them. So much so, in fact, that it's estimated that your body may spend as much as 30% of the energy available in the protein just to access the amino acids. Even if we go with a more conservative 20% number, it's easy to see that 50 calories of proteins may end up with only 40 calories actually getting into your body when everything is said and done. Combine that with the fact they are generally slower digesting (your body has to untie all those knots) and they keep you feeling full longer and it's easy to see why proteins are a very important part of a balanced dietary intake.

Wrapping Up
The phrases 'you get what you pay for' and 'garbage in, garbage out' really hit home in relation to macronutrients. Use the guideline of eating the best quality of food that you can on a regular basis. If an entire meal costs a dollar or two, you can likely bet that the quality is matching the price and you'll be paying for this later. Since we exercise a couple of times a week but we eat a couple of times a day, it makes sense to become knowledgeable about the different macronutrients and their roles in your body. Eat healthy, live well, and have fun discovering food that treats your body right.

By Jim Cook