In the twenty-first century, many of us have been trained to have an aversion to carbs or fat, but most people regard protein foods as safe foods. They absolutely are. But a lot of the things we are told about protein just aren't true.
Exaggerations About the Body's Need for Protein
Chances are you have heard at least one of these "facts" about protein:
- Everybody needs to eat protein every 2 or 3 hours, about an ounce (30 g) the ideal serving size.
- You have to eat protein after you work out so your muscles can rebuild and reshape themselves into a stronger, firm, larger form.
- If you don't eat protein several times a day, you'll lose muscle mass.
- Vegans and vegetarians can't build muscle mass.
And, of course, we have all heard that the more protein you eat, the more muscle you'll build, even while you lose fat mass, or so some experts tell you. But what is the truth about protein?
Amino Acids Are Like Lego Blocks
The hundreds of thousands of different proteins in the human body, and in our food, are assembled from just 22 amino acids. These amino acids have to be linked together in an exact sequence for the protein they are used to make to function properly in the body. Your body assembles amino acids to make muscle, red blood cells, white blood cells, nerves, brain cells, inner organs, skin, hair, fingernails, toenails, and hormones. Every cell contains some protein.
The process of digestion, however, doesn't break down long chains of amino acids in food into 100% single amino acids. Instead, protein digestion, which mostly takes place in the stomach, breaks food proteins down into double, triple, and longer chains of amino acids, along with some of the single, amino acids. This means your body has to fit the right blocks in the right places. And the body can transform an amino acid it does not need into an amino acid it does need, with nine exceptions:
These are the essential amino acids. There are also some amino acids that are conditionally essential, meaning that the body can make them only when their source amino acids aren't needed for something else. These amino acids are:
Your body can make the other amino acids as they are needed. Meat, fish, eggs, and milk provide all 22 of the amino acids that the body needs to make protein. Certain plant foods provide almost all the 22 amino acids the body needs to make its own proteins:
- Beans, peas, and lentils other than soy may be deficient in cysteine, methionine, and tryptophan.
- Corn doesn't provide lysine and tryptophan.
- Rice and wheat don't provide lysine.
- Soy is usually deficient in methionine.
It's not hard to get complete protein from plant foods, however. Rice and wheat and don't provide lysine, so eat them with beans, peas, lentils, or soy, which do. Corn (the grain and the vegetable, not the high-fructose corn syrup) is a little more problematic, but it is still very useful when you eat a lot of different plant foods. You can get all the amino acids your body needs by eating a variety of plant foods. Amaranth, buckwheat, hempseed, and quinoa, by the way, provide almost complete protein. So what's not to love about plant foods as your source of protein?
The body not only can transform proteins into each other, it can also transform proteins into sugar and fat. When you eat a complete protein food, your body tends to process it into amino acids. When you eat an incomplete protein source, your body tends to process it into sugar and fat. Your body can't store amino acids. If you eat too many grains, your body will store them in your fat cells. The solution is not to eat too many grains, especially if you are eating other sources of protein.
What about green vegetables as a source of protein?
You may have heard that spinach, for example, provides more protein that steak. And the claim is not a complete fabrication. If you desiccate a piece of sirloin steak in a drying oven in the lab, protein analysis will find 26 grams of protein in 30 grams of your sirloin steak jerky. If you desiccate a serving of spinach in the same drying over, the analysis will show 10 grams of protein in 30 grams of dried spinach. It's an exaggeration only by about a factor of two.
However, if you cook the steak, you'll get 26 grams of protein in 100 grams of steak. And you'll get 2 grams of protein in 100 grams of raw spinach, or 4 grams of protein in a nice, big bowl of spinach salad. The real question is, how much protein does your body really need?
Protein requirements vary dramatically from person to person.
Some vegans survive, and even thrive, on just 20 grams of protein a day. Some bodybuilders consume 500 grams of protein a day, the amount of protein in nearly 4 pounds (1750 g) of meat. Adult bodybuilders are never 25 times a big as adult vegans, so where does all the extra protein go?
Once your body has all 22 of the amino acids it needs in the amount it needs for one day, more protein you eat, the greater the proportion that is converted to sugars and burned for energy or stored as fat. And in addition to the protein you get from the food you eat, your body "recycles" about 100 grams of protein a day. This means that even if you are the vegan who consumes just 20 grams of protein a day, your body actually processes six times that much, just to be sure you have all the amino acids you need in the right amounts and the right sequences. These proteins come from saliva, pancreatic juices, and red blood cells that have leaked into the small intestine.
And just 100 grams of protein a day is about all your body can use to make muscle, no matter how hard you exercise. (Ironically, research sponsored by a protein powder maker found that consuming additional protein does not result in additional muscle mass.) You can eat more without harming your health, but you are just providing your body with a very slow and steady source of sugar, digested far more slowly than the sugars in carbohydrate foods.
How often do diabetics need to eat protein? And how much?
In 2007, a paper published in the American Journal of Clinical Nutrition reported the results of an experiment in which volunteers were asked to eat one meal a day, or three meals a day, either diet providing the same amount of protein. At the end of eight weeks, the researchers found no difference in muscle mass.
The scientific evidence is that we do not need to eat protein every three hours to prevent protein deficiency. Once a day is definitely enough. Once every three days may be enough, because our bodies recycle our own proteins from saliva and digestive juices.
This means that you could live without meat as long as as you don't eat too many carbs. As a practical matter, most type 2 diabetics do eat meat, but a lot of the meat they eat actually gets turned into sugar because the body cannot use all the amino acids. A single serving of meat, the size of a deck of playing cards, usually provides more than enough protein for nutritional needs.
Everything else is about your taste preferences. As long as you are not consuming vastly more protein than your body can use, and you do not have diabetes-related kidney disease, we don't see a lot of harm in eating meat, eggs, fish, and dairy at every meal. It's simply not necessary.