Protein

So we talked about fat last week. It seems like the natural next step is to discuss protein. Or to me it does. And since I’m the one driving this ship, you get to follow my instincts.

Most of us probably associate protein with muscle and working out and body building. But I want you to keep in mind that protein also makes up our hair and nails, our skin, most of our internal organs, bones, hormones, transport proteins in our blood… basically every cell in our body uses protein. It’s not just athletes who need it.

Protein itself can be broken down into chains of individual amino acids. We can make a lot of the amino acids ourselves, but there are a handful that we can’t make and HAVE to get from our diet – the essential amino acids. This is where debates about plant-based proteins and animal-based proteins come in. Animal sources of protein (meat, cheese, eggs) are a complete protein source. They have all the amino acids we need. Plant proteins (tofu, beans, textured vegetable protein, etc) will be lacking in at least one essential amino acid. It used to be that vegetarians and vegans were told that they had to worry about food combining, such as eating rice with their black beans, because if they ate two different foods with different amino acid contents the entire meal would form a complete protein and they could get all the amino acids they need. Now research is showing that as long as they eat a varied diet they’ll be fine. You can eat your beans at lunch and save your rice for your dinner and be completely healthy.

beans-and-veg

(And no, quinoa is not a complete protein. It contains very low levels of tyrosine and phenylalanine.)


Official Recommendations

The Recommended Dietary Allowance (RDA) for protein is 0.8 g/kg body weight. But that’s the amount considered sufficient to meet the protein needs of 98% of the population. Basically the amount most people need to prevent malnutrition.

But that’s just a starting point. It’s likely fine for sedentary people.

Many of us are moving around throughout the day and need a little bit more than that. The International Society of Sports Nutrition (ISSN) recommends 1.4-2.0 g/kg body weight for physically active people. This helps repair and maintain lean muscle tissue. After we workout (whether resistance training, endurance training, or anaerobic HIIT-style workouts) the rate of muscle breakdown actually increases to a level higher than muscle synthesis. This is why we’re told to eat a post-workout meal that contains protein. If we workout and don’t eat protein then we’re just breaking down our muscle. If we workout and then eat protein, we’ll have those building block amino acids available from our meal to help rebuild our muscle. (If you don’t eat until a few hours after a hard workout, your muscles will still benefit from the dietary protein but because that muscle breakdown and synthesis has slowed down, the benefit won’t be as great.)

Once we reach the age of 65 the recommended protein intake actually increases to 2.0 g/kg of body weight. Due to a variety of reasons, our appetites tend to start decreasing as we age and if we aren’t eating enough over all, we don’t get enough dietary protein to support normal body functions and our bodies end up plundering protein from places like our muscles and bones. And age-related loss of lean body tissues is associated with higher morbidity and mortality. So it’s really important to focus on eating more protein as we age.

I actually heard a story recently about an 89 year old lady whose doctor told her to start eating eggs. She said she couldn’t because she has high cholesterol. Her doctor responded that if she doesn’t increase her protein intake she’ll die of a broken hip long before she’ll die of a heart attack. Not only will eating higher amounts of protein help us maintain our muscle mass as we age, which helps our strength, balance, and coordination to prevent falls, but women with higher protein intake have higher bone density. So often when an older person falls and breaks a hip, we don’t actually know whether they fell and the hip broke because of the fall, or whether their bone density has decreased so much that the hip breaks, causing the fall.


More Benefits

So protein helps us maintain our lean body mass – yay! There are a few other benefits as well.

Dietary protein has a higher thermic effect in the body, meaning it takes a lot more energy to actually breakdown the protein we eat and use it compared to carbs or fat. The thermic effect of protein may be as high as 30%. That means 30% of the energy we’d get from a protein-rich food is used just to break it down and absorb it. In comparison, the thermic effect of carbohydrates is less than 10% and fat is less than 5%. So protein foods help us burn calories!

(Kind of. We’re still able to use that other 70% of the calories in the protein for energy or storage as fat.)

Protein foods also stimulate the release of satiety hormones when we eat them – we’ll feel full sooner and potentially take in fewer calories.

So these, plus the preservation of lean body mass are all really important benefits of protein when trying to lose weight. It can provide it’s own calorie burn, it’ll make us feel full so we can eat less over all, and it’ll maintain our muscles, which help us keep a higher calorie burn in their own right.

And because protein is used throughout the body we can maintain normal bodily function, hormonal signaling, and even immune function. A study in Marine recruits actually found that those who received a protein supplement after exercise had 33% fewer medical visits over all and 28% fewer visits related to bacterial and viral infections compared to recruits who didn’t get the supplement.


Can We Eat Too Much?

Yes.

Though maybe not for the reasons that immediately come to mind.

Most people are under the impression that eating a high protein diet is hard on the kidneys because the kidneys then have a lot more protein byproducts to filter out of our blood. But that’s true during the muscle breakdown after exercise too. Eating a high protein diet doesn’t damage our kidneys if they’re already healthy. It can exacerbate damage that is already there though, which is why individuals in the early stages of kidney disease are told to limit their protein intake.

What about cancer? The China Study said that people who eat diets higher in protein are going to get cancer. Well you can’t believe everything you read. Researchers, particularly those who are simplifying their research to appeal to the masses, can put emphasis on things that they find important. Different scientists might interpret the exact same results in different ways. Don’t take everything at face value.

For example, the China Study used correlational research. Correlation is not the same as causation. It just happens to be that people who eat more protein make lifestyle choices that seem to lead to higher rates of cancer. Maybe they also tend to drink more alcohol, have a history of smoking, and lead sedentary lifestyles. It’s probably not the protein itself that causes the cancer. Because it’s only correlative we can’t know for sure.

Also, people in studies like these are asked to describe how much protein they’ve eaten for the past 10, 15, 20 years. Can you even remember what you had for lunch 3 days ago? Human dietary recall has been proven to be very poor, which makes the results of these studies unreliable.

When it comes to meat intake and cancer, the strongest links have been found to processed meats (i.e. hot dogs, pepperoni) and to charred meats. So those slightly blackened hot dogs off the grill during your summer barbeque? The charring causes carcinogens to develop. Carcinogens cause cancer. At low-levels they might not be dangerous, but after repeated, frequent exposure they become a greater and greater risk.

hot-dog

So maybe lay off the charbroiled hamburgers at your favorite fast food restaurants.

One last thing – if we eat too much protein our bodies will convert it to glucose to be used for energy. And if we have enough energy from the rest of our meal, it will end up getting stored as body fat. So please don’t use this information to decide to shift to a high protein diet. Unless you’re a weight lifter or bodybuilder, you really don’t need it.

 


So what do those recommendations really look like?

How do you know that you’re getting enough? If you eat a standard American diet it’s easy to get 0.8 g/kg of body weight a day.

If you find yourself hungry between meals, try adding a little more protein (or a little more fat) to your meals and see if that helps.

If you’re working out and find that it’s taking you longer to recover after a workout than it used to (prolonged fatigue or muscle soreness), maybe add an extra serving of protein to your day and see if it helps.

Your doctor can also run a few different lab tests to tell you whether you’re getting enough or eating too much.

So what do those recommendations above look like in real life? Let’s use me as an example. I’m a 59 kg, healthy, 31 year old female. I workout 5-6 days a week (mostly free weights with 1-2 days of HIIT style cardio) and on my ‘rest’ day I work a rather physical job kneading loaves of bread and lifting heavy pans and racks at a bakery.

Last week my diet consisted of:

  • 2 scrambled eggs + 1/4 cup of egg whites at breakfast (20 grams of protein)
  • 1/2 cup of tofu + 1/4 cup of beans + 1 hard boiled egg on a salad at lunch (17.5 grams of protein)
  • Chicken tortilla soup (let’s say 1 breast per serving) + 1/4 cup plain Greek yogurt (31 grams of protein)

So on an average day I was eating 65 grams of protein from major protein sources. That’s about 1.1 g of protein per kg body weight. But because all food contains at least a little bit of protein, I was actually getting more. MyFitnessPal estimates that I get closer to 95 grams of protein per day, but I use a lot of estimates and approximations when I log my food so it’s not a very reliable source. But 95 g of protein is actually more like 1.6 g/kg body weight and a better fit for my needs on days that I workout and get in a couple of walks with the dogs.

Does that help you at all? I focus on eating protein from a variety of source (both plant and animal-based) and I’m not eating crazy large portions of each item, but it’s enough to keep me full between meals and I don’t find myself horribly sore after workouts. As a result I’m happy with how I’m eating and don’t feel the need to change anything about my protein intake. That might change as the weather grows warmer, my daily schedule changes, and I start running more and lifting weight less and if it does I’ll change my diet to reflect it.

It doesn’t need to be an exact science. I actually think this is the first time that I’ve analyzed how many grams of protein I’m eating and how that falls into the recommendations.

I eat foods that I enjoy (the Greek yogurt in the chicken tortilla soup definitely enhances the flavor) and plan meals that will leave me satisfied. I recommend that you do the same. If I have a few days in a row where I find myself hungry between meals I’ll increase my protein and/or my fat intake and see if that helps.


Resources

Nutritional quality of the protein in quinoa (Chenopodium quinoa, Willd) seeds.

Nutrient Recommendations: Dietary Reference Intakes (DRI)

ISSN position stand: protein and exercise

Postexercise protein supplementation improves health and muscle soreness during basic military training in Marine recruits.

Known and Probable Human Carcinogens

USDA Food Composition Database


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