Fats, carbohydrates and proteins are a group of nutrients known as the macronutrients. Macronutrients are the body's source of energy (calories) fueling daily activities, exercise and recovery from injuries. Protein is a special macronutrient because unlike fats and carbs, it provides the building blocks for all tissue within the body. The body uses protein to build new tissues and repair damages ones. The gym-community sees protein as a muscle building miracle food; more protein=more muscle. Unfortunately this isn't always the case. Many people eat way too much protein leading to excessive increases in body fat rather than faster muscle growth.
What is Protein?
Protein is a macronutrient providing four calories of energy per gram. Proteins are made up of amino acids: the building blocks of all tissue within the body. In addition to providing energy, proteins are also used to build and repair tissue; a unique ability fats and carbs cannot fill.
Protein is the nutrient at the center of the muscle building universe. More protein leads to more muscle, at least that's what the gym-scientists say. Natural (steroid-free) muscle growth is limited to about 10-15 pounds of gains per year for most people. There are a few factors limiting muscle growth, some of them we can influence and others, we can't. The amount of strength training you engage in and calories you consume speed up muscle growth to a certain point, but genetics and limitations of the human body are the main reasons we can't build muscle any faster.
Building muscle requires energy. Muscle growth can only happen when you combine a calorie surplus (a state in which you consume more calories than you burn) with more exercise. If you burn 2,500 calories per day, muscle growth happens when you consume more than 2,500 calories and engage in some sort of exercise. This extra energy combined with stimulus in the form of physical activity, leads to muscle growth.
Increasing calorie and protein intake speeds muscle growth to a certain point. Once the body is building muscle as quickly as possible (10-15 pounds per year), any extra calories (protein included) get stored as body fat. A calorie surplus can cause weight gain in the form of muscle and/or body fat. Eating more does not always lead to faster muscle growth, but it frequently leads to excessive increases in body fat.
How Much Protein
A quick Google search on how much protein is appropriate for muscle growth reveals a wide array of opinions ranging from adequate to excessive.
Many gym articles, blogs and forums geared towards casual exercisers, recommend 2-4 grams of protein per pound of body weight. This recommendation is not an appropriate intake level for the average person who visits the gym few times per week and only hopes to burn some body fat and run a mile in 10 minutes. As the evidence below suggests, an intake of 2-4 grams of protein per pound of body weight is excessive even for serious athletes.
There are a few places we can look to for protein intake guidance: 1) the Institute of Medicine's (IOM) Acceptable Macronutrient Distribution Ranges (AMDR) and, 2) studies looking at protein requirements for athletes.
Acceptable Macronutrient Distribution Ranges for Protein
The Institute of Medicine (IOM) sets acceptable macronutrient distribution ranges (AMDR) for each macronutrient (fats, carbs and proteins). The AMDR for protein is currently set at 10-35% (for adults) of overall calorie intake. In other words, 10-35% of your daily calorie intake should come from protein. For example:
- 3,000 total calories
- 10% of 3,000 calories = 3,000 x .10 = minimum 300 calories from protein
- 35% of 3,000 calories = 3,000 x .35 = maximum 1,050 calories from protein
- 300 / 4 = minimum 75 grams of protein
- 1,050 / 4 = maximum 263 grams of protein
If you're on a 3,000 calorie diet, the AMDR recommends an intake of between 75 and 263 grams of protein per day.
The AMDR was setup to meet the needs of most individuals. Athletes have higher calorie and protein needs than the average person due to increased physical activity levels.
Another recommendation is the RDA or recommended daily allowance. The RDA is defined as, "average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%-98%) healthy people." The RDA for protein is currently set at 0.8 grams of protein per kg of body weight or 0.36 grams of protein per pound of body weight.
Both the AMDR and RDA for protein are much lower than the 2-4 gram/pound recommendation coming from gym blogs and forums.
One study published in the Journal of Sports Sciences recommends an intake of 1.3-1.8 grams of protein per kilogram of bodyweight per day (or 0.59g-0.82g of protein per pound of bodyweight).
A review study published in Clinical Nutrition Insight, found endurance athletes need 1.2-1.6 grams of protein per kilogram (or 0.54-0.73 grams of protein per pound) during low-moderate intensity activities and 1.6 grams per kilogram (or 0.73 grams of protein per pound) for higher intensity activities.
The same review study found resistance trainers need 1.7 grams of protein per kilogram (or 0.77 grams of protein per pound) as beginners, decreasing to 1.2 grams of protein per kilogram (or 0.54 grams of protein per pound) as well trained bodybuilders. Athletes in football, hockey and other power sports require 1.4-1.7 grams of protein per kilogram (or 0.64-0.77 grams of protein per pound).
The general consensus between all the studies is athletes need between 1.2 and 1.8 grams of protein per kilogram of body weight per day (or 0.54-0.82 grams of protein per pound). This recommendation is higher than the IOM's AMDR because athletes are much more physically active than the average person.
Example (0.54-0.82 grams of protein per pound of bodyweight)
- 150 pound athlete
- 81 - 123 grams of protein per day
- 200 pound athlete
- 108 - 164 grams of protein per day
Consequences of too Much Protein
Gym forums and blogs greatly inflate the need for protein. Two-four grams of protein (per day per pound of body weight) is much higher than the average person's need of 0.36 grams and still higher than an athlete's need of 0.54-0.82 grams/pound of body weight/day.
These blogs' and forums' recommendations are getting average people to follow intake levels much higher than what is recommended for highly trained athletes. An average person taking in 2-4 grams of protein per pound of body weight is excessive and unlikely to yield benefits beyond the intake recommended by the IOM's AMDR (10-35% of overall calories) or RDA (0.36g/day). Rather than building muscle, these levels of protein intake will likely lead to excess body fat.
Muscle growth happens very slowly and there is very little we can do to [naturally] speed it up. Sufficient calorie and protein intakes are required to gain muscle, but once these needs are met, simply eating more protein (via food or supplement) does not speed up growth.
A calorie surplus (consuming more than you burn) fuels muscle growth. An ever increasing calorie surplus does not fuel more or faster growth. Once the body is building as much muscle as it can, more calories and/or protein leads to a buildup of body fat.
Body fat is defined as calories eaten above the body's energy needs. The body storing fat is a sign you're eating too much. Fat does nothing to speed up muscle growth and should be avoided. Though protein is a unique nutrient, excessive amounts of any of the three macronutrients are stored as body fat.
The Bottom Line
The recommendation from the IOM's AMDR (10-35% of overall calorie intake) is sufficient to meet the average person's protein requirements. Higher protein recommendations meant for serious athletes provide too much protein for the average person. If you're not running long races, competing in bodybuilding/powerlifting competitions or playing competitive sports, you are probably not considered an athlete as far as these protein recommendations are concerned.
If you are having issues with excessive soreness or declining performance, consider slightly increase protein intake (though the possible causes of excessive soreness and poor performance go beyond just protein). More protein, however, does not always lead to more muscle. If you're gaining body fat along with muscle, the issue is that you're eating too many calories and possibly too much protein.