This is a common question that I get asked almost everyday. Protein intake varies depending on the individual and a plethora of other factors such as age, activity level, type of activity, and how much lean mass you have. Individuals with higher activity levels or who engage in intense, heavy lifting and/or high volume endurance training or who have a high amount of lean mass obviously need to eat more protein. All individuals need to intake a minimum amount of protein for normal bodily needs and functions.
A general rule of thumb is to intake protein based on body weight. The majority of textbooks and research that I have come across state that individuals need anywhere from .37-.50 grams/lb of body weight. Since I am a 130 lbs (129.9 lbs to be exact) I need to intake anywhere from 48-65g of protein per day just to maintain normal health and function. This method is not exact at all, however, due to the fact that it does not take into consideration activity level or lean body mass.
Why is it important to consider lean body mass?
A more specific method of calculating how much protein you need is using your lean body mass. Lean body mass is defined as all the tissue in your body other than fat (bones, muscles, water, organs). Lean body mass requires more protein because, unlike fat mass, it is metabolically active. To calculate this you need to have your body fat measured either through bio-electrical impedance or skin folds calipers. Once you know your body fat you can calculate how much lean tissue you have. I am 130 lbs and 15.4% body fat. This means that of the 130 lbs that I currently weigh I am storing 20.02lbs of fat and the other 109.98 lbs are lean mass. This is the number you will use to calculate your protein needs based off activity level.
Why is activity level important?
During activity and exercise we stress the skeletal muscle of our body. In fact we actually damage the tissue by causing small micro-tears in the contractile proteins. Skeletal muscle is comprised mostly of protein and we need dietary protein to repair and rebuild existing skeletal muscle or even build new muscle mass if this is part of your goal. Use the amount of lean tissue you have to calculate protein requirements:
Sedentary – multiple lean body mass by .5
Light activity (e.g. walking) – multiply by .6
Moderate (30 minutes of vigorous activity 3 days per week) – .7
Active (1 hour per day 5 days per week) – .8
Very Active (10 hours of vigorous activity per week – .9
Athlete – multiply by 1.0
Since I have 109.98 lbs of lean body mass and I am considered to be Very Active during a normal week of exercise and daily activity I need to be eating roughly 99g of protein per day. This is more than double the minimum 48g of protein recommended prior to considering lean body mass and activity. So you can see why it is extremely important to take these additional factors into consideration to ensure that you are getting adequate protein. Lack of protein can leave your body unable to repair and recover from exercise. Rather than constantly being consumed with counting grams of protein, focus on adding protein to every meal and snack. In taking even a small amount of protein will help to reach the levels you need for your body on a daily basis.