When I start working with a client on their nutrition, one of the first things I commonly tell them is that their number one priority each day should be staying within their daily calorie allotment, and their number two priority should be hitting their daily protein goal. Why is this? What makes protein so special that the only dietary goal that supersedes it is total caloric intake?
First, we need to understand what protein is for. If you’re not already familiar, the three macronutrients in our diet are protein, carbohydrate, and fat.
Although each macronutrient plays some unique roles in the body, carbohydrates and fats are primarily just fuel sources. Proteins, on the other hand, or more specifically the amino acids that make up proteins, are the building blocks your body uses to make all of your living tissues; muscles, organs, bones, nerves, skin, even hair and finger nails are all made up of proteins.
Antibodies are also made of protein, which means insufficient protein intake can actually lead to a weakened immune system. For these reasons, along with many others, getting the right amount of protein is essential to good health.
How much protein do I need?
Figuring out how much protein you need shouldn’t be that difficult, but you may get some conflicting advice on the subject. If you go to your doctor, they’re likely to quote you the old Recommended Dietary Allowance (RDA) of 46 grams of protein for women and 54 grams of protein for men, but there are a few major problems with these numbers.
The first issue with these numbers is that they are based on calculations for a 127 pound woman and a 154 pound man, so if you don’t fit either of those descriptions, you’re already starting off on the wrong foot. The other problem with these numbers is that they are based on achieving a level of sufficiency, rather than optimal health.
This is actually a problem with many of the RDA numbers. They are essentially the minimum amount you need of a given nutrient just to avoid getting sick, not to live your best life. For the RDA of protein, the basis of this calculation is an intake .8 grams of protein per kilogram of mass.
A few years ago, the Institute of Medicine (IOM) came out with what they call the Acceptable Macronutrient Distribution Range (AMDR). In releasing these ranges, the IOM acknowledged that macronutrient requirements vary greatly between individuals, based on a wide variety of factors. For protein, they said intake should be between 10-35% of total caloric intake. That is a huge range.
For our 127 pound woman and 154 pound man, from the RDA calculations, assuming they are both of average height and average age, their ranges would be anywhere from 30-105 grams for the woman and 40-138 grams for the man.
I should also add that those numbers are based on our man and woman eating only enough calories to satisfy their Base Metabolic Rate (BMR), which is the amount of calories needed to maintain your current weight at essentially zero physical activity.
Now, if those ranges seem insanely broad, don’t worry, the same AMDR recommendations state that protein intake should fall between 1.2-1.8 grams per kilogram of mass. That would narrow the range for our 127 pound woman to 68-102 grams per day, and our 154 pound man would have a range of 84-126 grams.
There are two things you should immediately notice about that last set of numbers. First, the bottom end of those ranges are still well above the old RDA numbers; in fact, they are a full 50% higher than the numbers we mentioned your doctor might be quoting to you as adequate amounts of protein.
The other thing you should notice about those refined numbers is that they are in the upper end of the initial 10-35% ranges we calculated. As we mentioned, the numbers we’ve been using are based on caloric loads at BMR, or the bare minimum amount of food necessary to maintain your current mass. What that should indicate to you is that the fewer calories you are consuming, the higher your protein intake should be as a percentage of total calories.
Many people are under the impression that higher protein intakes are something only bodybuilders or athletes require; this is actually far from the truth. While an athlete or bodybuilder will likely require more protein than a less active person, it won’t be that significant of an increase.
Remember that we said all of the living tissues in your body are made up of proteins, including the antibodies in your immune system. The overwhelming majority of the protein you eat goes to maintaining these tissues and systems, not supporting extraneous physical activity.
The biggest difference in the dietary requirements of an athlete versus an average individual of the same weight will be in the amount of fuel they require, the carbohydrates and fats, not the protein. An elite athlete may require up to two times the total calories of a sedentary person of similar size, but they will likely require no more than maybe a third more protein in most cases.
This means the more calories you require, relative to bodyweight, the lower your protein intake will be as a percentage of total calories. Individuals who are less active, or who are restricting calories in order to lose weight, will need to eat protein at a higher percentage of total calories than similar individuals who require higher caloric loads.
Another thing to keep in mind about the numbers we have been discussing is that these are still all based around our 127 pound female and 154 pound male, from the old RDA numbers, eating a minimal amount of calories. If you are closer to the US national average of 170 pounds for women or 197 pounds for men, and you have an even moderately active lifestyle, your protein requirements will be significantly higher.
But where’s the magic?
One of the other big differences in the three macronutrients, aside from their uses in the body, is their thermic effect. The digestion of food is a complex chemical process, and there is a certain amount of energy either used or lost, as your food is moved through the digestive tract and broken down into its usable components. The more the food has to be processed, the more energy is lost.
Fats and carbohydrates are relatively good to go, with only minor breaking down from their ingested forms, so the thermic effect of their digestion is fairly minimal, being about 4% for fats and 6% for carbohydrates. Proteins, on the other hand, have to be broken down into their base amino acids, then collected by the liver, which functions as a sort of project manager for amino acids, to be repackaged for various purposes in the body. This is a very expensive process, and it results in a thermic effect of almost 25%.
What this means is, while almost 100% of the calories you consume from carbohydrates and fats result in a net energy gain in the body, which must then be either used or stored, only about three quarters of the calories you consume from protein are metabolically impactful. That means eating higher percentages of total calories as protein can be highly beneficial for weight loss.
Protein also stimulates the release of cholecystokinin (CCK), a hormone that slows the emptying of the stomach, which allows more time for dense proteins to be broken down. This means a meal high in protein will leave you feeling full for a longer period of time. If you have trouble with nervous eating, increasing your protein intake can have a profound effect on your level of satiety between meals, making it much easier to avoid mindless snacking.
Despite all of these things, the most magical aspect of increasing your protein consumption has to be its impact on body composition. Whether you are trying to lose weight, gain weight, or just maintain your current mass, study after study shows that increased protein intake, as a percentage of total calories, will result in more muscle and less fat.
What does it all mean?
Your takeaway from all of this should be that getting enough protein in your diet is vital for optimal health and body composition. Daily intake of protein for the majority of individuals should be between 1.2-1.8 g/kg of bodyweight, and unless you are consuming calories at a very high rate, it should make up at least 25-30% of your total caloric intake.
by Coach Chris Woods