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Wednesday, June 19, 2013

PROTEIN REQUIREMENTS

The current recommendation for protein is to consume .8g/kg of body weight per day. A 150-lb individual adhering to this advice would consume 56 grams of protein per day. As each gram of protein has 4 calories, this equates to roughly 225 calories, or about 11% of calories on a 2,000-calorie per day diet.

Advocates of higher protein intakes argue that this recommendation does not apply to everyone, since the data on which it was based derived from studies involving sedentary individuals, and active folks would seem to need more protein. If athletes (and if you exercise regularly, this means you) do require more protein, reflected as grams per day, how much more depends on the type of exercise you engage in.

Authorities suggest that endurance athletes require additional protein as an auxiliary fuel source, while those who engage in strength training require extra amino acids to serve as building blocks for muscle synthesis. Although both groups (marathoners and muscleheads alike) would seem to require more protein than sedentary individuals, the additional protein requirements in grams per kg per day for endurance aficionados is less than for bodybuilders.

Here are the recommendations for a 150-lb individual:

1. Sedentary individuals: .8g/kg/d or 56g/224 calories, which we've stated is 11% of calories on a 2,000-calorie per day diet.

2. Endurance athletes: 1.3g/kg/d. This is 90 g/protein a day, or 360 calories. Since endurance training typically consumes somewhere between 600 and 1,000 calories per hour depending on intensity, the calorie requirement for runners is higher than for sedentary individuals, and endurance athletes often require 3,000 calories per day to replace glucose and glycogen stores. 90g/day of protein is 12% of calories on a 3,000-calorie per day diet.

3. Strength training: 1.6g/kg/d. This is around 110 grams per day, twice the amount required by sedentary individuals. Strength training burns more calories than sitting but less than swimming, so the caloric requirements for weight lifters are somewhere between the endurance athlete and the couch potato. Let's say 2,500 calories per day for the 150-lb person. Four hundred forty calories is 18% of 2,500. Therefore, our weight lifter should aim to consume around 18% of his calories from protein.

Now the question arises, where to get the extra protein? You don't need to look very far. As most foods contain at least 10% protein - and in the case of beans, seeds, and many vegetables as much as 20 to 40% - simply eating more food will ensure that you meet your daily protein quota.

And remember that choosing complete protein sources is not necessary. This myth, propagated in the 80s, has been roundly dispelled. All foods provide all amino acids, and choosing a variety of fruits, vegetables, beans, and seeds will easily fulfill the protein requirement for individuals of all ages and activity levels. No need for protein bars and fancy powders and other expensive supplements that by taxing the digestion and acidifying the blood do more harm than good. Opt instead to eat more leafy greens, which as the above chart shows are very high in protein. Legumes (beans, peas, lentils) are another good option. One can of kidney beans has 20 grams of protein. Two cans a day (40 grams protein) are what separates the couch potato from the ultramarathoner. Well, that and about 30 miles.

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