Protein is an essential nutrient that is a part of every cell in your body. It plays a vital role in hormonal processes, the health of your bones, hair, and skin, and promotes fat loss and muscle gain. There is no reason to believe that eating protein will harm your kidneys or other organs (if they are already healthy), and many different sources — from plants to animals — can be a part of a healthy diet without added risk.
While both carbs and fats have spent time as the scapegoat for common health problems like weight gain, no macronutrient has enjoyed a rise to prominence as much as protein.
A favorite in health and beauty, and with bodybuilders, athletes, and just about any fitness enthusiast, protein is used by your body to repair damaged muscle, bone, skin, and hair, among other things. Think of it as the mortar between the bricks; without it, the entire structure of your body begins to break down.
Unlike other nutrients, your body can not assemble protein by combining other nutrients, so prioritizing protein is important if you want to achieve your healthiest (and best looking) body possible.
Protein helps to create an ideal environment for changing the way your body looks (research suggests it’s good for muscle building and helping with fat loss). And it’s a natural “dietary behavior” to follow because protein is in a wide variety of foods, which means that getting enough protein in your is usually a sustainable behavior because it doesn’t require extreme actions.
That said, not all proteins are created equal, and not everyone needs the same amount of protein every day. Here’s everything you need to know about protein, your health goals, and any potential dangers.
There are two categories of protein: complete and incomplete. Protein is comprised of smaller molecules called amino acids. There are twenty-two amino acids that warrant attention, of which nine you need to get from your diet. Your body can manufacture the remainder of the amino acids.
The nine amino acids that you must get from your diet are called essential amino acids. These include:
A complete protein (also known as a whole protein) is one that contains adequate portions of those nine amino acids. By contrast, an incomplete protein is one that is lacking in one or more of those amino acids. Foods that contain all amino acids include fish, poultry, eggs, red meat, and cheese.
In the world of protein powders, whey is a complete protein, as is casein and soy. Most plant-based proteins are not complete, although pea protein (what you'll find Ladder Plant) does contain all of the essential amino acids.
These amino acids also help your body create hormones that help regulate things like blood pressure and blood sugar levels, which are directly responsible for your metabolic rate and muscular growth.
Supports Fat Loss and Muscle Gain
Protein has the distinct reputation of helping both fat loss and muscle gain. On the surface, it doesn’t even make sense how the same foods could support both goals. But, once you understand the many values of protein, it’s easy to see how it can help both.
From a weight loss perspective, protein is very filling. When you are trying to lose weight, your hunger becomes a factor and anything to reduce hunger is valuable.
Your body breaks down protein for energy at a higher rate when losing weight. Unless you want to lose that muscle mass you worked on so hard to build up, you need to increase your protein intake.
Protein has the highest thermic effect of food (TEF), which is the number of calories your body needs to burn to digest the food. So while one 1 gram of protein is four calories, once you factor in TEF, it’s more like three calories. Or, in broader terms, for about every 100 calories from protein you consume, you burn about 30 of those calories during the digestion process.
What’s more, your body is not very good at converting protein into fatty acids (which is stored as body fat). Thus, eating a lot of protein has a greater chance of building muscle or being used for energy, but not for storing body fat.
When it comes to building muscle, weight training causes muscle damage, and protein is needed to stimulate the growth and repair process — something known as muscle protein synthesis (MPS). Protein alone can help promote MPS, but when you combine it with resistance training, that’s when muscle-building magic occurs because MPS helps your muscles adapt, recovery, and reduce muscle protein breakdown (MPB), or the process by which your body uses protein to help fuel the metabolic processes within your body.
Because the process of building muscle requires damage to muscle tissue caused by metabolic and mechanical stress, the process of growth is supporting by a recovery and adaptation process that requires new protein synthesis to repair damaged proteins in your muscle. That’s why eating additional protein is so helpful, and why it can support both fat loss — and muscle gain. It’s not about being bulk; it’s about providing your body with the nutrients it needs to support both processes on a physiological level.
Is Protein Dangerous?
Despite having decades of research, The China Study triggered new skepticism and concern. (It’s important to mention this is a book based on research observations, not a scientifically designed study.) While some of the claims are downright terrifying and could lead anyone to a plant-based, low-protein diet, research tells a different story. [Editor's note: this is not to say there’s anything wrong with a plant-based diet. What you eat is your choice; the goal is to make sure you’re clear on the risks.]
Most protein-fear revolves around a link between protein intake and something called hepatocarcinoma.
In scientific terms, for protein to cause this problem, there must be aflatoxin toxicity (very rare), and without reaching certain levels of aflatoxin in the body, there is no significant link between protein and liver toxicity.
So what is aflatoxin? In the most basic sense, it’s a toxic mold that can be present in proteins, and it’s one of the central arguments behind the idea that protein can harm kidneys, do liver damage, or even cause cancer.
On paper, it all seemingly makes sense, except for the fact that essential details are left out.
Most importantly, while aflatoxins can indeed be a problem, reaching those dangerous levels through protein is no small task. In fact, for most people, it might not even be realistic.
To quote Dr. Chris Masterjohn, a professor and researcher in health and nutrition sciences,
“If your friend offered you peanut butter sandwiches with 100 grams worth of peanut butter contaminated with the maximum amount of aflatoxin allowed by the FDA, you’d only have to eat 270,000 peanut butter sandwiches for four days to obtain the dose of aflatoxin that produced a ‘barely detectable response’ in Campbell’s study.”
If protein safety is in question, it’s because we’re stretching the truth of the real danger it poses. While the likelihood of protein-related aflatoxin issues is low, there are a few other conditions where you might need to watch your intake. The key being, if you’re healthy, then you’re not in danger if you want to enjoy daily protein shakes and feast on chicken and steak.
Some “experts” would like to have you believe that eating lots of protein will cause all sorts of problems, ranging from kidney stones and gallstones.
If you’re healthy, you are clear to eat protein and not worry about any health problems—because there are none.
For most people, this is not a concern—or rather, it is a moot point. That’s because there’s no research showing any relationship between eating lots of protein and developing kidney problems.
A study in the Journal of Strength and Conditioning Research tested up to 400 grams of protein per day without any negative consequences. Now, if you have a preexisting kidney problem, it’s possible that a higher protein diet could be hard on your body. But if you have a kidney problem, you should be talking to your doctor about your diet anyway.
The only case where both dietary protein and your liver are related is for anyone who suffers from hepatic encephalopathy, a liver condition that alters protein metabolism.
Otherwise, there really is no significant concern for liver damage in a practical setting for an otherwise healthy person.
Some doctors also worry that higher protein diets can lead to greater excretion of calcium, which could cause issues with bone density or osteoporosis.
According to Examine.com, this isn’t correct:
In looking at large survey research, there appears to be no relation between protein intake and bone fracture risk (indicative of bone health) except for when total calcium intake was below 400mg per 1000kcal daily.
One intervention study noted that protein intake was actually positively associated with bone mineral density, but this correlation only was shown when the acidic effects of sulfate.
In other words, if you have any concern, make sure you have enough calcium in your diet, and there should be no concern.
What About BCAAs?
Branched-chain amino acids or the BCAAs are three amino acids (leucine, isoleucine, and valine) that play a crucial role in muscle growth, and might support fat loss as well. However, while these amino acids are great, you don’t need to supplement them if you ingest enough daily protein. You don't need extra BCAAs because when you consume enough complete protein, that protein will convert into its metabolites (BCAAs) in your body. Not to mention, newer research shows that taking BCAAs alone — without other essential amino acids — has little-to-no impact on muscle protein synthesis or muscle protein breakdown.
How Much Protein Do You Need?
If you’re looking for a very general guideline, you should eat about .5 to 1 gram per body of your goal body weight. In simple terms: if you want to weight 150 pounds, then you’d aim for anywhere between 75-150 grams of protein per day. How do you differentiate between the lower and higher end? If you’re very active, you can veer slightly upward, and if you’re less active, then eat less.
Want a more detailed approach? Protein recommendations are usually given relative to your body weight, instead of in absolute terms. Unless you are morbidly obese (calculate protein usage based on your target weight), the rough guidelines are
0.5g/kg body weight: This is the Recommended Daily Allowance (RDA) for protein. It’ll keep you alive and in general health. This is the minimum, and by no means should be considered the only level that is safe. (Research shows you can consume much more if you desire or it benefits your goals)
0.5-1.0g/kg body weight: This is a higher range mostly used by health-conscious people or people who are new to exercise and are trying to build some muscle.
1.0-1.5g/kg body weight: This is the typical recommendation for building muscle and reaching your athletic goals.
1.5-2.2g/kg (1g/lb) body weight: This is mostly recommended based on anecdotal evidence, but more research is beginning to support this recommendation as an upper threshold.