What is protein? How much protein do we need? Is it possible to eat too
much protein? These are important questions for people following a low
carb way of eating, who usually are replacing part of their
carbohydrate intake with protein.
What is protein?
Protein is one of the basic building blocks
of the human body, being about 16 percent of our total body weight.
Muscle, hair, skin, and connective tissue are mainly made up of
protein. However, protein plays a major role in
all
of the cells and most of the fluids in our bodies. In addition, many of
our bodies' important chemicals -- enzymes, hormones,
neurotransmitters, and even our DNA -- are at least partially made up
of protein. Although our bodies are good at “recycling” protein, we use
up protein constantly, so it is important to continually replace it.
Proteins are made up of smaller units called amino acids. Our bodies
cannot manufacture nine amino acids, so it is important to include all
these amino acids in our diets. Animal proteins such as meat, eggs, and
dairy products have all the amino acids, and many plants have some of
them.
How much protein do we need?
Our protein needs depend on our age, size, and activity level. The
standard method used by nutritionists to estimate our minimum daily
protein requirement is to multiply the body weight in kilograms by .8,
or weight in pounds by .37. This is the number of grams of protein that
should be the daily minimum. According to this method, a person
weighing 150 lbs. should eat 55 grams of protein per day, a 200-pound
person should get 74 grams, and a 250-pound person, 92 grams.
Another way to compute protein needs has to do with lean body mass. This method is discussed in the Zone Diet and Protein Power books.
Do people who exercise need more protein?
Although it is controversial, there is evidence that people engaging in
endurance exercise (such as long distance running) or heavy resistive
exercise (such as body building) can benefit from additional protein in
their diets. One prominent researcher in the field recommends 1.2 to
1.4 grams per kilogram of body weight per day for endurance exercisers
and 1.7 to 1.8 grams per kg per day for heavy strength training.
But shouldn’t protein intake be a percentage of total calories?
Quite
a few programs and nutritionists quote percentage of calories, usually
in the range of 10 percent to 20 percent, as a way to figure out how
much protein a person needs to consume daily. This is a rough estimate
of a person's minimum protein needs. It works because usually larger
and more active people need more calories, so the more calories they
need, the more protein they will get.
Where this falls down is when people are eating diets which are lower
in calories for any reason, conscious or not. People who are ill or
losing weight, for example, do not need less protein just because they
are eating fewer calories.
What happens if we don’t eat enough protein?
Unlike fat and
glucose, our body has little capacity to store protein. If we were to
stop eating protein, our body would start to break down muscle for its
needs within a day or so.
Is it OK to eat a lot more protein than the minimum recommendations?
This is the crucial question for people on diets which are higher in
protein than usual, as low-carb diets tend to be. In a review of the
research, the National Academy of Sciences reported that the only known
danger from high protein diets is for individuals with kidney disease.
After careful study, they recommend that 10 percent to 35 percent of
daily calories come from protein. They point out that increased protein
could be helpful in treating obesity. There is also accumulating
evidence that
extra protein in may prevent osteoporosis
.
Extra protein can be broken down into glucose in a process called gluconeogenesis.
On low carb diets, this happens continually. One benefit of obtaining
glucose from protein is that it is absorbed into the bloodstream very
slowly, so it doesn’t cause a rapid blood sugar increase.
What foods have the most protein?
Meat, fish, eggs, dairy products, legumes, and nuts all have substantial amounts of protein. Helpful information:
Beef
- Hamburger patty, 4 oz – 28 grams protein
- Steak, 6 oz – 42 grams
- Most cuts of beef – 7 grams of protein per ounce
Chicken
- Chicken breast, 3.5 oz - 30 grams protein
- Chicken thigh – 10 grams (for average size)
- Drumstick – 11 grams
- Wing – 6 grams
- Chicken meat, cooked, 4 oz – 35 grams
Fish
- Most fish fillets or steaks are about 22 grams of protein for 3 ½ oz (100 grams) of cooked fish, or 6 grams per ounce
- Tuna, 6 oz can - 40 grams of protein
Pork
- Pork chop, average - 22 grams protein
- Pork loin or tenderloin, 4 oz – 29 grams
- Ham, 3 oz serving – 19 grams
- Ground pork, 1 oz raw – 5 grams; 3 oz cooked – 22 grams
- Bacon, 1 slice – 3 grams
- Canadian-style bacon (back bacon), slice – 5 – 6 grams
Eggs and Dairy
- Egg, large - 6 grams protein
- Milk, 1 cup - 8 grams
- Cottage cheese, ½ cup - 15 grams
- Yogurt, 1 cup – usually 8-12 grams, check label
- Soft cheeses (Mozzarella, Brie, Camembert) – 6 grams per oz
- Medium cheeses (Cheddar, Swiss) – 7 or 8 grams per oz
- Hard cheeses (Parmesan) – 10 grams per oz
Beans (including soy)
- Tofu, ½ cup 20 grams protein
- Tofu, 1 oz, 2.3 grams
- Soy milk, 1 cup - 6 -10 grams
- Most beans (black, pinto, lentils, etc) about 7-10 grams protein per half cup of cooked beans
- Soy beans, ½ cup cooked – 14 grams protein
- Split peas, ½ cup cooked – 8 grams
Nuts and Seeds
- Peanut butter, 2 Tablespoons - 8 grams protein
- Almonds, ¼ cup – 8 grams
- Peanuts, ¼ cup – 9 grams
- Cashews, ¼ cup – 5 grams
- Pecans, ¼ cup – 2.5 grams
- Sunflower seeds, ¼ cup – 6 grams
- Pumpkin seeds, ¼ cup – 8 grams
- Flax seeds – ¼ cup – 8 grams
By Laura Dolson
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