Science-Backed Answers to Four Common Questions About Protein Intake
If you lift, you know you need protein to build muscle (as well as water and calories). But how much protein? Or when? What type of protein?
If you look around the Web, you’ll find all sorts of different answers to those questions. Some are backed by science, others backed by “bro-science.” In this article, we’ll talk about priorities when it comes to protein, and break down each priority with the strongest evidence available.
Let’s begin with the hierarchy of protein needs:
At the bottom of the pyramid is the most important (total daily protein intake), and at the top is the least important (peri-workout protein intake). This means you should prioritize the lower levels of the pyramid before attempting to optimize the higher levels of the pyramid.
Now that’s out of the way, we’ll break down each part of the pyramid by answering the following common questions:
How much protein should I eat per day?
How much protein should I eat on a diet?
What kind of protein should I eat?
How should I break up my protein?
How much protein should I eat per day?
The USDA protein recommendation for strength trainees is 1.2-1.7g/kg (or 98-139g/day for a 180 lb person). I know what you’re thinking: “That’s way too low! It goes against the bro-science of 1g/lb of bodyweight.” But there’s actually some research to back this up where they compare high intakes of protein with lower ones. In one key study,1 they compared 0.77g/lb (1.7g/kg) of protein to 1g/lb (2.2g/kg) and found no significant differences in body composition, strength or hormonal concentrations over a three-month period.
At the top of the hierarchy of research, we have a meta-analysis2 that looked at 49 studies and concluded protein intakes beyond 0.7g/lb posed no benefit in gains in fat-free mass (muscle). It’s important to note that these studies were done with subjects at maintenance or surplus level of calories. If that is you, I’d recommend 0.8g/lb of bodyweight, just a little bit above the cut-off point in studies just for some extra cushion. You can choose to go above this for your preference if your calorie intake is very high and you have the “budget” for it. But if you don’t have a large calorie budget, it could potentially hamper performance, since you’d be taking away calories from carbohydrates.
How much protein should I eat on a diet?
During a diet that restricts calories, protein intake should increase for a few reasons:
Protein is the most satiating macronutrient, meaning it helps keep you satisfied and full after eating
Protein helps retain lean body mass, which will help maintain metabolic rate
Although the benefits are very small, protein has the highest thermic effect of all macronutrients, meaning its energy demands to digest are higher (burns more calories)
Calories are protein-sparing, so lower calories mean a greater likelihood of using protein for energy
How much protein should you eat while on such a diet? One informative review3 looked at several studies and concluded that 1.0-1.4g/lb of lean body mass is sufficient, scaling upwards for lower body fat levels and steeper caloric deficits. This amount of protein intake, coupled with a slow rate of weight loss (<0.7% of body weight loss per week), should be sufficient to minimize or negate any losses in lean body mass.
What kind of protein should I eat?
One of the big reasons why we want protein is to accrue new muscle tissue growth. That comes from muscle protein synthesis exceeding the rate of breakdown. Simply put, muscle protein synthesis is spiked from consuming all the essential amino acids (EAAs), largely due to leucine. Animal products (meat and dairy) cover all the essential amino acids, so consuming animal proteins is an easy way to make sure you’re getting in quality protein. If you are vegetarian or vegan, you’ll probably have to be more strategic in getting in all your EAAs. It’s possible, but it’s harder.
As for the science, one interesting study4 compared milk protein vs soy protein after a workout in young, trained weightlifters. It found the soy protein group gained less lean body mass. Another study5 compared whey protein vs soy protein in trained individuals and found lean body mass gains to be 45% less in the soy protein group over a 36-week period.
Soy is actually a complete protein source with a strong leucine content for being plant-based, yet it still does not hold up as well as animal proteins (e.g. whey). The point of sharing those two studies, then, is to show that ingesting a higher quality protein (i.e. richer in leucine) can yield better results. It doesn’t necessarily have to be whey protein. Pretty much any meat or dairy product will have all essential amino acids with a high leucine content. Just don’t get your protein from incomplete or lower-quality protein sources.
How should I break up my protein?
To answer this question about protein distribution throughout the day, resarches in one study6 compared an evenly distributed protein intake across three meals with a “skewed intake” (low protein breakfast, moderate lunch, high dinner) in resistance-trained men. They found that the evenly distributed protein group had better results for muscle hypertrophy.
In another key paper7 (by friends of IronQuest Brad Schoenfeld and Alan Aragon), researchers investigated the maximum amount of protein that can be consumed to be used towards anabolism, or fully saturating muscle protein synthesis. Any protein consumed beyond this amount may not be used for building new tissue as it could be oxidized for energy or used for other bodily processes in which protein plays a role. The number they came to in the end was 0.4g/kg (0.18g/lb) per meal, for four meals a day (1.6g/kg or 0.72g/lb of protein per day, in line with my above recommendation).
In summary
Here’s an easy way to figure out your protein needs in a calorie surplus/maintenance situation:
Bodyweight (lbs) x 0.8 = grams of protein per day
(grams of protein per day) / number of meals (3-5) = protein per meal
And here’s the formula for when you’re in a calorie deficit:
Lean body mass (lbs) x 1-1.4 = grams of protein per day
Also remember to focus on high-quality protein sources from animal products — meats, whey and other dairy products (yogurt, cheese, milk) — and you’ll be good to go.
James Pak is a nutrition expert with multiple certifications from the National Academy of Sports Medicine and the Clean Health Fitness Institute. He is also a competitive powerlifter holding national and state records in the Southern Powerlifting Federation. You can find out more about James and his coaching services by clicking here.