How Much Protein Do We Really Need?

Every time I watch a documentary on global warming, the idea of cutting down on energy consumption seems to get completely glossed over and the take away is: EAT LESS MEAT. I also hear this from the health community. When I was in school to become a dietitian, the constant message was that people are EATING WAY TOO MUCH meat; we’re getting more than enough protein.

I think the growth of the vegan and vegetarian movement is based primarily on emotions, with cherry-picked data to back it up with “logic.” Meat has long been considered “evil.” In fact, corn flakes were invented by John Harvey Kellogg to stop masturbation. He felt that eating spicy, protein-rich foods lead to increased sexual arousal. The guy was on a mission to end sex all together, which he felt was at the root of many health issues like epilepsy and cancer. In addition to advocating a meatless diet, did all kinds of sick things, especially to kids and women.

Today, eating a plant-based diet is still associated with being “clean” and “pure.” When looking at the “levels of vegetarianism,” eating red meat is considered the “worst,” with no real logic to back this up in my mind. How is eating chicken a “cleaner” choice than beef? If you’ve ever raised chickens, I’m sure you’ll agree that they are NOT clean, pure, or any better of a choice than a cow, sheep, or lamb. Chickens are actually quite dirty and are cannibals; they will peck each other to death if stressed – and CAFOs are pretty stressful on chickens.

Environmentalists say that beef is destroying the environment, and health advisors are saying that it’s killing us. As a “real food” dietitian who lives on a working farm, I understand the importance of properly raised herbivores in helping to sequester carbon. I tend to talk about the benefits of meat in nutrition to environmentalists, and talk about the importance of regenerative agriculture to the nutrition crowd. There doesn’t seem to be a lot of overlap in these two areas. It’s like you can’t possibly be “pro planet” and “pro meat” at the same time. Am I really the only one who thinks this is possible?

There seems to be a big disconnect. I personally don’t think that you have to give up meat if you want to be an environmentalist. I wonder if our assumption that we’re eating “so much protein/meat” is actually a result of feeling guilty about eating meat in general.

“When you assume, you make an ass out of you and me.” – Mr. Mangano, my high school math teacher.

When I attend the environmental conferences, I don’t see any dietitians on the “How Much Meat Should We Eat?” panels. It’s usually a bunch of chefs saying, “Less Meat, Better Meat.” This is a very popular position to take, but is it correct? I don’t see data/studies being referenced on how much meat we’re ACTUALLY eating, or how much protein humans really need.

So, I decided to do some research. How much protein do we actually need? What is this based on? How much protein/meat are we actually eating? Is it really too much, enough, or too low? What are the best sources of protein for vegetarians? Why do women in particular avoid red meat? Originally, I thought this would a simple, maybe 500 word post. I actually opened a big can of worms, so I need to break it into several separate posts. Here’s the answer to the first question, plus a look into what happens when we over or under eat protein.

1. How Much Protein Do We Actually Need?

According to the US Dietary Guidelines, the RDA (Recommended Daily Allowance) of 0.8 grams of protein per kg of bodyweight. In the case of protein, the RDA of 0.8g/kg is the minimum amount to avoid loss of lean muscle mass.

The current RDA for protein intake is explained in the Dietary Reference Intakes by the Institute of Medicine, which based protein intake recommendations on nitrogen balance studies. Nitrogen balance is the difference between nitrogen intake and excreted nitrogen. It’s difficult to measure, and varies greatly between individuals. It’s very easy to underestimate adequate protein levels based on these studies. In fact, here is a direct quote from the paper, “In adults, it is generally presumed that the protein requirement is achieved when an individual is in zero nitrogen balance. To some extent, this assumption poses problems that may lead to under-estimates of the true protein requirement.”

Way before these guidelines were introduced, much higher protein recommendations were proposed. In this 1912 book, nitrogen balance studies were questioned as inaccurate measures of protein requirements, and a recommendation of at least 100 grams of digestible protein (so, not just grams of protein, but the bioavailability of the protein) be consumed.

Translating the RDA of 0.8g protein/kg BW to the public is difficult (some people I’ve talked to don’t even know what protein is), so the folks who put together the US Dietary Guidelines decided to give actual numbers to people. They based the numbers on a “reference” man of 70kg (154lbs) and a “reference” woman at 57kg (125lbs). So, if you look up, “How much protein should I eat?” the numbers you’ll often find are 56 grams a day for men and 46 grams per day for women. These are based on 0.8g protein per kg BW based on those references. The problem is, how many men do you know who are 154lbs and women who are 125lbs? NOT MANY.

I then checked out what the CDC says for the average American man: 88.6kg (195.5lbs) and the average woman is 75.6kg (166.2lbs). That’s a big difference from the above “ideal” man and woman! According to the 0.8 grams of protein calculation, that the average American man needs 71 grams of protein per day and the average American woman needs 60 grams, at a minimum. This still represents a relatively low protein intake in my opinion, so I kept looking around for more information.

There’s this other protein guideline called the Acceptable Macronutrient Distribution Range (AMDR). The AMDR is defined as “a range of intakes for a particular energy source that is associated with reduced risk of chronic diseases while providing adequate intakes of essential nutrients.” The recommended range for protein according to the ADMR is 10% – 35% of caloric intake. (In the 1977 guidelines, the recommendation was only 10% – 14%)

The USDA Estimated Caloric Needs Per Day recommends about 2000 calories per day diet for average, moderately active women and about 2600 calories per day for moderately active men. The “reference” woman is 5 feet 4 inches tall and weighs 126 pounds and the “reference” man is 5 feet 10 inches tall and weighs 154 pounds. Again, these are not “average” weights for Americans. Using 10%-35% of calories from protein, the reference woman would need 50 – 175 grams of protein per day, and the reference man needs 65 – 228 grams of protein per day. This is a very large range! This makes the RDA of 0.8g/kg at below the ADMR range. So, given this context, are we still eating too much protein?

Interestingly, I found a post published by the US Library of Medicine, recommending a person on a 2,000 calorie diet get 20% of their calories from protein. This means a target of 100 grams per day. This number is about DOUBLE what the US Dietary Guidelines recommend.

I was also wondering if the US Military had slightly different recommendations. There is a Military Recommended Daily Allowance (MRDA) for rations. MRDA for protein are based, in part, on an estimated nutritional requirement of 0.8 gm/day/kg of body weight. (See table 2–1.)

“Protein allowance is based on an estimated protein requirement of 0.8 gm/kilograms (kg) desirable body weight. Using the reference body weight ranges for males of 60 to 79 kilograms (132 – 173lbs) and for females of 46 to 63 kilograms (101 – 138lbs), the protein requirement is approximately 48 to 64 grams for males and 37 to 51 grams for females. These amounts have been approximately doubled to reflect the usual protein consumption levels of Americans and to enhance diet acceptability.”

When you see the table, the protein recommendation is 100grams. Why would the army just go ahead and DOUBLE the protein recommendations, if they were based on any kind of science?

And if things were’t confusing enough, I looked at “My Plate” recommendations, which are intended to be how the US Dietary Guidelines are broken down into “simple” terms, to used as a mass teaching tool. Here is what they recommend for intake from “protein” foods:

You’ll see that the protein recommendations are listed as ounce “equivalents”. My Plate says, “In general, 1 ounce of meat, poultry or fish, ¼ cup cooked beans, 1 egg, 1 tablespoon of peanut butter, or ½ ounce of nuts or seeds can be considered as 1 ounce-equivalent from the Protein Foods Group.”

The problem is that the ounce equivalents really aren’t equal if you look up the grams of protein they have. One ounce chicken or roasted beef equals about 8-9 grams of protein, 1 oz of fish is about 6, and 1 egg has 6 grams. For the non-meat options, 1 tablespoon of peanut butter has 4g protein and 1/4 cup of cooked beans has 4.2 grams of protein. So, if a woman following the above guidelines ate the recommended 5 ounce equivalents of protein they would get about 6 grams per ounce, for about 45 grams per day.

Now, My Plate also recommends 3 cups of milk for men and women. It also offers other options to drinking milk, “In general, 1 cup of milk, yogurt, or soymilk (soy beverage), 1 ½ ounces of natural cheese, or 2 ounces of processed cheese can be considered as 1 cup from the Dairy Group.”

1 cup of 1% milk has 8g of protein. 1 cup of low fat yogurt has about 11g of protein, 8 grams in a cup of soy milk, and 1.5 oz of natural cheese has 10g of protein, so when you add the dairy in, the average woman is getting about 27 more grams of protein from the milk group, on top of the protein foods group. However, many people in the world are lactose intolerant, and milk is not part of the dietary guidelines of most countries. Three cups of milk/servings of dairy is a lot in my opinion. 

There is also some protein (not much) in grains and vegetables, so this could add on a few more grams. So, when you look at it, the My Plate recommendations actually equal about 75g of protein when you add dairy and other foods to the “protein foods” group for the “average” woman and 81g of protein for “average” men. This is at the lower end of the ADMR of 10% – 35%. For a woman, 75g of protein on a 2,000 calorie diet is only 15% of calories from protein, and it’s an even lower percentage, at 12 % for a man on a 2600 calorie diet. These are the caloric recommendations in the US Dietary Guidelines for men and women with “moderate” activity levels, ages 26 – 45. Also, the guidelines say that we should limit our sugar intake to less than 10% of calories. How is protein basically at the same nutritional status as sugar? No wonder why nobody trusts nutrition advice anymore.

2. Are there dangers of eating too much protein?

According to the Dietary Reference Intakes by the Institute of Medicine, “the current state of the literature does not permit any recommendation of the upper level for protein to be made on the basis of chronic disease risk.” and, “high protein intake had no detrimental effect on protein homeostasis.” This study also showed no harmful effects of a diet of  >3g/kg/d in healthy, resistance-trained men.

In my clinical practice, when I recommend about 100 grams of protein a day, largely from animal sources, I sometimes get push back. Some women tend to think it’s “gross” to eat that much, and they think it’s too “heavy” or they feel bad to be eating so many animals. I address the moral argument here, and am exploring women’s relationship to red meat more in this recent post. I find that most men don’t argue quite as much. When I tell them to eat meat, they are pretty psyched.

Others have heard that meat can cause cancer and is harmful to the kidneys. The fact is, in healthy people, increased protein intake has no harmful effect on the kidneys at all. The kidneys simply adapt. While low protein diets can be therapeutic for those with kidney disease, this does not mean that a high protein diet caused kidney disease. Chris Kresser expands on meat and it’s relation to kidney function, cancer, and IGF-1 (it’s probably the methionine, not the protein) in this post.

There are several hunter gatherer cultures that eat lots of meat, however just because they’re eating meat, doesn’t meat their diet is only protein. One study of an Eskimo population in 1855 found that when they were eating an “all meat” diet, their protein intake was only 44% due to high fat intake. During times of plenty, they would consume 4 to 8 pounds of meat a day, with a daily average food partition of about 280 gm. of protein, 135 gm. of fat, and 54 gm. of carbohydrate of which the bulk is derived from the glycogen of the meat eaten. Early American explorers survived for extended periods of time only on pemmican, a food made of dried lean meat mixed with fat, with a protein content of 20 to 35%.

Protein is the most satiating of the macronutrients, and intakes of 15% – 30% of caloric intake can be quite helpful in regulating appetite by increasing leptin sensitivity and induces weight loss and increase blood sugar control. In this meta-analysis, high protein diets of 25% – 32% of calories compared to the control groups of 15% – 20% (which is still higher than the RDA), showed beneficial effects on weight loss, HbA1C levels and blood pressure in patients with type 2 diabetes. This post shows that increased protein seems to be the key to a hunger-free diet, as weight loss in two studies was successful in both low-carb and low-fat diets when protein was between 22% – 25%.

3. What are the dangers of eating too little protein?

Your body needs protein, and if you don’t get it through diet, your body will start breaking down your muscle and other tissues in order to get protein. This leads to muscle wasting and weakness. Immune function decreases because protein is required for antibodies.  Adequate protein is also required for bone health. You also need protein as enzymes and to carry oxygen to tissues, so low protein can cause lethargy. Low protein is also associated with hair loss, brittle nails and cold hands and feet. Low protein can cause weight gain. B12 deficiency (a vitamin only available in animal protein) has been shown as an independent risk factor for coronary artery disease and serious neurological disorders in infants of vegan mothers.

4. So, how much protein should you eat?

In summary, we are being told to eat 0.8g/kg of protein per kg of bodyweight. We’re also being told by My Plate that nearly 60% of our dietary intake of protein should be in the form of dairy or soy milk products. It’s incredibly confusing to determine how much meat to eat and the recommendations don’t really seem to be based on much science, due to the inaccuracy of nitrogen balance studies and the gigantic ranges from the ADMR.

It seems that 100g of protein on a 2,000 calorie diet is a very reasonable amount, and many of you are eating much more than 2,000 a day, so this means beef up your protein, folks. Most Americans report eating between 1800 and 2500 calories per day (and self-reported data is usually on the low end) so this means, at 20% of calories, intake for Americans should really be between 90 and 125 grams of protein per day. If you’re getting this from meat, that looks like around 12oz – 16oz of meat a day. Break that between three meals, and this is 4-6oz of animal protein per meal. More if you’re eating more calories, or have a need for increased protein. So, the next time someone says to you we need to eat “less meat, better meat,” please share this post with them, and ask them how much protein they’re actually eating.