Taking Control of Your Dietary Composition Part 8


by Fred DiMenna, Ph.D.

If you want to eat to promote health and achieve a specific body composition (e.g., lose fat, gain muscle or maintain your current levels in the face of passing years), the first step is to take control of your energy balance. This is necessary because inherent mechanisms designed to modulate this equilibrium have been circumvented due to changes in the modern lifestyle. If you know how much energy you ingest each day and consider this in relation to the amount you expend, you can adjust your energy balance according to what you wish to accomplish. For example, you can lose a pound of fat per week by either ingesting 500 kilocalories less each day or expending 500 more. The bottom line is that through trial and error, you can determine the caloric allotment required to attain your goals after which you can choose to 'spend' this quota any way you desire. It is only logical to choose a strategy designed to maximize health.  

It is necessary to take control of your dietary composition once you know how much energy you should take in each day. For example, if you determine that you have 2,000 kilocalories at your disposal (think of this as money left over for discretionary spending), does it make sense to spend 550 of it on a Big Mac? Probably not for a number of reasons not the least of which is that it is an energy source that does not provide optimal nutrition in terms of where its energy is contained. There are three sources of energy in food (the macronutrients; i.e., protein, carbohydrate and fat) and each is required for healthy function. The USDA has determined that a healthy diet should contain 10-35 percent of its energy in the form of protein, 45-65 percent as carbohydrate and 20-35 percent as fat. If you spend over a quarter of your daily allotment on a Big Mac, you'd like to find that its energy distribution falls within these ranges. Unfortunately, this is not the case. A Big Mac contains 25 grams of protein and each gram of protein contributes four kilocalories, which means that 18 percent of the Big Mac's 550 kilocalories is present as protein. Given that this is within the desired range, this food is adequate in this regard. However, carbohydrate (34 percent) and fat (48 percent) are underrepresented and overrepresented, respectively. This is par for the course as carbohydrates have become macronutrient non grata and if you consider the facts, it's hard to figure out why.

Carbohydrates are molecules that contain three elements – carbon, hydrogen and oxygen. Interestingly, fats are made of the same three elements; however, they appear in different proportion as there are more carbon and hydrogen atoms and less oxygen atoms  in fats. Considering that the energy in macronutrients is contained in the chemical bonds that hold their carbon and hydrogen atoms together, this explains why fats are denser sources of energy (nine kilocalories per gram as opposed to four). Carbohydrates can be further classified into simple sugars composed of either one or two sugar units (i.e., monosaccharides and disaccharides, respectively) or complex carbohydrates (starch and fiber) comprising long chains. These distinctions are important because a carbohydrate's structure ultimately dictates what will happen once you eat it (e.g., simple sugars digest quickly, starches digest slowly and fiber does not digest at all). Quite often, broad-brush anti-carb theories fail to take these distinctions into account. Furthermore, once any of the three macronutrients is ingested, if the energy contained within its bonds is not required immediately to perform mechanical work (e.g., to contract your muscles to jog) or synthesize new cells (e.g., to build muscle after resistance training), it will be stored and storage takes place in a number of forms.

When carbohydrates are ingested, they are broken down and absorbed into the bloodstream primarily in their simplest form, which is glucose. When blood passes through the liver, approximately 30 percent of the additional glucose is metabolized while the rest continues its journey around the body. Blood glucose is closely regulated, so if the circulating amount that is in excess of the required level (70-130 milligrams per deciliter) is not needed immediately, it will leave the bloodstream to be stored in a less transient form. Glucose units can be strung together into long-chain molecules called glycogen, which are stored in the liver and muscle. Once this option is maxed out (generally speaking, 100 grams of glycogen are stored in the liver with 200 stored in muscle), the remaining excess is deposited in adipose tissue as fat. However, it's important to note that any extra protein or fat ingested above that which is immediately required will meet the same fate. Consequently, it is extra macronutrient energy per se as opposed to macronutrient energy in a specific form that is responsible for fat gain. This means that contrary to popular belief, a low-carb diet that is high in protein won't necessarily compromise your ability to store excess energy as fat. But a low-carb diet that is high in protein will definitely compromise your ability to store excess energy as glycogen and this can have a negative impact on your health.   

This article was originally published in New Living Magazine, which can be accessed on-line at www.newliving.com.




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