Several factors can affect protein needs
Protein requirements can vary based on age, gender, genetics, health and the quality of the protein. For this reason, we can only define how much protein a person needs by giving general guidelines.
Doing the math
It is generally thought that every day we need about 7 grams of protein for every 20 pounds of body weight. This means that if you weigh 150 pounds, you would need about 52.5 grams of protein each day.
150 ÷ 20 = 7.5 7.5grams x 7 = 52.5grams
Many health experts put it a different way by saying that we should get about 30% of our calories each day from healthy eating protein sources. Protein has about 4 calories per gram, so if you consume 2400 calories a day, about 720 of them should be from protein.
2400 calories x 30% = 720 calories
Selections from the Pyramid
Yet another way of putting it is in reference to the Food Guide Pyramid, which for many years was a way to visualize the amount of food you should eat from each of the five food groups, each day. By this method, depending on your weight, you need two to three 3-ounce servings of meat, fish, poultry or meat analog each day. (A meat analog is a soy or grain based product that is manufactured to look and taste like certain meat products.)
Note - The USDA has introduced a newer concept to replace the pyramid called simply "My Plate." This model provides a visual representation of the variety of foods that should regularly be found on our dinner plates, including protein.
What this means to you
Okay, so you’re not a mathematician, you’re a gourmand, and you don't want to sit around doing equations to find out what you should eat. Suffice it to say, that if you live in a developed country such as the USA, it is more likely that you are getting too much protein than not enough.
When you consider that most foods have some protein and many foods, as listed above, have significant protein, if you are eating three square meals a day, you are probably getting enough protein. However, if you live in an underdeveloped country, protein deficiency may be a real concern. People in poor countries struggle to meet the minimum requirements for protein.
If you have eggs (possibly with bacon or sausage) or cereal with milk or toast with peanut butter for breakfast, a salad with chicken breast or a ham and cheese sandwich or minestrone soup for lunch, and a hamburger or a pork chop or spaghetti and meatballs for dinner, you are most likely getting more than enough protein. Even if you skipped one of those meals, you probably are still getting enough protein.
What makes a serving?
If you misplaced your meat scale, the usual guideline for visualizing meat servings is that the portion should be the size of a standard deck of playing cards. (Just imagine how many servings are represented by that platter-sized prime rib served at your favorite restaurant!)
For non-meat protein sources, a serving, which is 1 large egg, ½ cup cooked beans or rice, or 2 Tablespoons of seeds, nuts or peanut butter, is equivalent to only about 1/3 of the protein in a serving of meat. Tofu can also be included in this group with a serving size of about 4oz.
In addition, most health experts recommend that, whenever possible, choose a leaner or low-fat version of the significant protein sources.
Complete or Incomplete?
Another aspect of protein requirements, is that foods that contain all of the essential amino acids are called “complete proteins.” These complete protein foods are generally animal foods. Plant foods do not, as a rule, have complete proteins, but by eating combinations of plant foods, called “complementary proteins, ” you can obtain a complete protein.
For example, when you eat beans with rice, such as is often found in Mexican cuisine, you are obtaining a complete protein. The beans and rice complement each other, in that each has some of the essential amino acids and when eaten together, they provide all of the essential amino acids. It is generally believed by nutritionists that it is not necessary to eat these complementary proteins at the same meal.
Here is a list of complementary proteins, that is proteins that when eaten together become complete.
Legumes... with Nuts
Legumes... with Grains
Legumes... with Seeds
Legumes... with Dairy
Grains... with Dairy
Nuts/Seeds... with Dairy
Nuts/Seeds... with Legumes
Dairy... with Nuts/Seeds and Legumes
Protein Requirements - In most cases:
Complete Proteins = Animal proteins
Incomplete Proteins = Plant Proteins
Vegetarians and Vegans, in particular, need to be aware of the importance of the essential amino acids.
Protein Requirements: What if you don't get enough?
You probably know that protein is an important nutrient. For that reason, if there is not enough protein in your diet, it will have a noticeable effect on your health, from making you more susceptible to infections to actually causing you to waste away.
Severe protein deficiency is most often associated with starvation and malnutrition and is a major cause for concern in developing nations, especially among children. In developed countries, severe protein deficiency is mostly associated with those in extreme poverty or those suffering with eating disorders, such as anorexia nervosa. Severe protein deficiency can lead to death.
Protein Requirements: What happens if you eat too much?
As with anything, you can get too much of a good thing. If you eat too much protein, your body can convert it to energy, but if that energy is not used, it will be stored as fat, which could lead to obesity. In addition, eating too much protein puts a heavier load on the kidneys to get rid of the by-products of protein metabolism.
There has also been some suggestion of a link between eating large amounts of animal protein (which is usually accompanied by saturated fat), and heart disease, cancer and possibly diabetes. Although protein is good for you,don't overdo it.
Protein Requirements: What to remember
Eat some protein foods at each meal. Eat protein from a variety of sources. In the case of animal protein, concentrate on the leaner or low-fat types. Just for fun, investigate some of the protein foods from plants.