Taking Control of Your Dietary Composition Part 6
The first step when setting up an eating program to achieve your body composition objectives is taking control of your energy balance. This involves determining how many kilocalories (a.k.a., dietary calories or Calories with a capital "C") you should ingest each day. Discounting small differences in digestive efficiency, a Calorie is the same regardless of the food that provides it, which means that even if you eat the worst diet imaginable (e.g., junk food galore), you will lose body fat if you take in less Calories than you expend. But if you want to lose your body fat in a healthy manner, simply eating the right amount of Calories and ignoring the source isn't enough. Instead, you must also take control of your dietary composition by making wise decisions regarding the foods you choose to satisfy your caloric allotment.
Energy in food is provided by large molecules (macronutrients) that come in three forms ‒ protein, carbohydrates and fat. Importantly, all of these components are essential for good health, which means that all must be provided by the diet in appropriate amounts. However, some seem to get more respect than others. For example, both low-fat and low-carbohydrate diets have been en vogue in some circles and there is a general belief that high protein intake is important especially for athletes. Unfortunately, the end result is that many people who attempt to eat in a healthy manner wind up doing the exact opposite.
In the last installment, I explained why protein is an important macronutrient. However, this does not mean that the more of it you eat, the better off you will be. Granted, protein is responsible for tissue growth, so if you are training with weights to make your muscles bigger and/or stronger, it's essential to ingest enough. But muscle growth is a gradual process, so the additional amount of protein that is necessary for those engaged in resistance training isn't that much. As a matter of fact, it is endurance training that increases protein requirement to a greater extent because in addition to tissue repair, protein must also be used as a fuel during long bouts of challenging endurance activity (e.g., running a marathon). But even if you are an ultra-endurance athlete or fall into another population that requires more than the normal amount of protein (e.g., pregnant/lactating women and growing children/adolescents), there is no need to take in excessive amounts and, indeed, doing so might even prove unhealthy.
Research regarding whether excessive protein intake is harmful is equivocal. Tsunehara et al. (1990) investigated the dietary intake of second-generation Japanese-American men because they have rates of noninsulin-dependent diabetes mellitus (NIDDM) that are four times higher than men in Japan and found that their diet comprised more animal protein and fat for the same number of calories. What is more, Patti et al. (1998) used cultured muscle cells to demonstrate that amino acids (the building blocks of proteins) act as signalers that change the responsiveness of a variety of target cells to insulin. Importantly, this initiates protein synthesis, which is why it is necessary to ingest protein comprising a full complement of amino acids during the window of opportunity for muscle growth directly following a resistance training workout. However, they also found that insulin's action at multiple levels was blunted by amino acids, which could contribute to insulin resistance. This appears to underscore the need to eschew the typical more-the-better approach and endeavor to ingest precisely the right amount.
Excessive protein intake has also been linked to renal cell cancer (Chow et al., 1994) and increased risk of mortality in individuals suffering from kidney disease (Dwyer et al., 1994). Recognizing these findings, Metges and Barth (2000) recommend not ingesting more than that which is typically consumed by well-nourished populations in technically-advanced nations (e.g., two grams per kilogram bodyweight per day). Conversely, Martin et al. (2005) conclude that while excessive protein intake remains a health concern in individuals with pre-existing renal disease, research demonstrating a link between protein intake and the initiation/progression of renal disease in healthy individuals is lacking. To this end, Bilsborough and Mann (2006) state that from the limited data available on amino acid absorption rates, maximal safe protein intake is ~285 grams per day for an 80-kilogram male. However, they also suggest that to keep energy balance in check, a more practical approach is to limit protein to 1.5 grams per kilogram to ensure that a sufficient amount of the other macronutrients can also be ingested. Specifically, they stress the importance of carbohydrates especially for those involved in physical activity because without an adequate amount, an early onset of fatigue will occur and exercise performance will be compromised. Furthermore, carbohydrates provide glucose, which prevents the body from having to make this fuel by breaking down muscle. The take-home message is that while excessive protein intake (e.g., as much as 3.5 grams per kilogram) might be tolerable by healthy individuals, spending this many Calories on this macronutrient is unnecessary and will make it impossible for you to ingest enough of the other two macronutrients without energy consumption exceeding expenditure (i.e., without setting up the positive energy balance that is the recipe for storing fat).
This article was originally published in New Living Magazine, which can be accessed on-line at www.newliving.com.
