How Much Protein Do You Need?

This is a recently contentious topic with a new demographic loudly advocating for very large amounts of protein intake. I think it is worth dissecting what people are saying, what the science says, and trying to figure out what we actually need. The key points are:

• The government recommends 0.8 g/kg of body weight.
• Many people think they need 2.2g/kg of body weight per day (or 1 g/lb as its commonly stated). We'll call this the high protein diet or HP.
• Most elite athletes need 1.3-1.8 g/kg of body weight per day according to studies.
• Some body builders and weightlifters will go up to 2 g/kg of body weight per day when going through a period of cutting weight while attempting to keep as much muscle mass as possible.
• Most people train at a level far below that of the athletes in these studies, and it is unlikely they would benefit from more than 1.8 g/kg of protein.

Who cares?

Why does it matter if people eat too much protein? There are a few personal reasons, and a few public health reasons.

The personal downfalls to eating too much protein are:

• Unless you are running a caloric surplus, you are likely not getting enough carbs in general, and definitely not enough to support cardio or endurance training.
• Much of the protein needed to reach such high levels will likely be high in cholesterol and as a result your cholesterol levels may become elevated.
• Meat and eggs are how most people meet such high protein goals, and they are both expensive compared to plant protein and carbs.
• Consuming too much protein creates a nitrogen rich environment in the blood and forces the kidneys to work harder to filter it out, leading to chronic kidney disease in advanced cases.^[1][2][3]

The public downfalls are:

• Excess nitrogen in everyone's urine actually makes wastewater treament harder.^[4][5][6]
• Rich countries like the US and China overconsuming meat products creates an inflated demand leading to: unnecessarily increased prices and excessive deforestation in places like the Amazon to make way for more grazing land for cattle.^[7][8]

What is the RDA?

The government's recommended daily allowance (RDA) is typically cited as 60 grams of protein per day, or 0.8 g/kg of body weight.^[9] The 60 gram RDA is likely enough for some sedentary people, but not anyone that is active or large in any way. The body weight measure is a small improvement since it at least accounts for a person's size, but is still likely not enough for a lot of people.

What does the science say?

There is a lot of supporting research, but perhaps it's best to look at this paper, as it is well written, provides many citations of existing work, and is the most often cited by proponents of a "too high" protein diet, when in fact it does not show that diet to be recommended.^[10]

Novice vs. Elite

First, a technicality before we start looking at studies. Some studies are performed on novice athletes, and some on elite athletes. Our study notes that protein needs can change and even lower among experienced athletes.^[10:1] Additionally, it's worth noting that much of the interested population and readers would be considered novice athletes. Elite athletes typically spend between 10-25 hours per week training. They typically have sponsorships and often do not have a full time job outside of being an athlete. For example, one study qualifies elite endurance athletes as running more than 125 km per week during a maintenance phase of training, and elite body builders as training daily more than 75 minutes.

Additionally, those engaged in bodybuilding or extensive strength training, and those who are endurance athletes, often running or cycling many hours per week have a very different set of dietary needs.

Therefore, we can think of three primary groups:

1. novice athletes or non-elite athletes (most of us)
2. elite endurance athletes
3. elite strength-focused athletes

Notice that endurance and strength are lumped together for novices, as the training load is likely not sufficient to differentiate, although the novice can learn something from the differences between the elite athletes. Some studies we will look at note the difference and find different needs between all three groups.

The Science

When I ask people where they heard they need 1g/lb of protein they often point to this paper, or a blog post that cites this paper.^[10:2] I believe this is because the abstract states:

Elevated protein consumption, as high as 1.8–2.0 g · kg−1 · day−1 depending on the caloric deficit, may be advantageous in preventing lean mass losses during periods of energy restriction to promote fat loss.

What is this saying though? "Periods of energy restriction to promote fat loss" is what bodybuilders commonly call "cutting". These athletes will occasionally have periods where they lower their training volume, induce a caloric deficit, and attempt to lose fat mass (but not muscle mass). In these instances, they found that increasing protein intake can help retain the existing muscle while losing weight.

Clearly this has it's place, but is probably not the normal state that most people are looking for when they point to this study as evidence of the high protein diet.

The paper also states directly in the abstract:

that protein intakes in the range of 1.3–1.8 g · kg−1 · day−1 consumed as 3–4 isonitrogenous meals will maximize muscle protein synthesis

They arrive at this conclusion after reviewing a large number of studies within the paper. This paper is well worth reading in it's entirety.

Another broadly cited study states "The nitrogen balance data revealed that bodybuilders required 1.12 times and endurance athletes required 1.67 times more daily protein than sedentary controls." The study also shows that lean muscle mass was maintained in bodybuilders consuming 1.05 g/kg. ^[11]

Another literature review concludes that daily intakes of 1.0 g/kg, 1.3 g/kg, and 1.6 g/kg are recommended for those engaging in minimal, moderate, and intense physical activity, which more or less falls in line with the 1.3-1.8 g/kg recommendation of the original paper.^[12] It also explicity recommends avoiding more than 2g/kg as it can cause health issues.

Yet another study found that increasing protein for novice bodybuilders from 1.3 g/kg to a high protein diet of 2.6 g/kg showed no increase in protein synthesis, and they found excess amino acid synthesis in the higher protein diet, meaning that more amino acids were being taken in than could be turned into protein. ^[13]

There are many other studies that show similar data to these. The literature widely supports the following conclusions

• 1.3-1.8g/kg maximizes protein synthesis
• in periods of cutting/caloric deficit increased consumption to 1.8-2.0g/kg can help prevent loss of muscle mass

Macro Balance

It's worth pointing out again that if you are eating an excessive amount of protein, you are likely neglecting other important sources of nutrients. Endurance athletes in particular should pay attention here. Endurance sports induce very high carbohydrate requirements on athletes in order to keep muscle glycogen replenished. There is a wide amount of debate on this topic, but as one study points out, the joint position of the Academy of Nutrition and Dietetics, Dieticians of Canada, and the American College of Sports Medicine are to intake carbohydrates as follows:^[14]

• 1 hour of moderate exercise per day requires 5-7 g/kg
• 1-3 hours of moderate to intense exercise per day requires 6-10 g/kg
• 4-5 hours of moderate to intense exercise per day requires 8-12 g/kg

Consider a 75 kg athlete with a basal metabolic rate of 2,000 calories per day. An hour of exercise may raise the calorie needs to 2,400 per day. If the athlete consumes 2g/kg in protein, that is 150 grams of protein and 600 calories. Add on 6g/kg in carbs and thats 450 grams of carbs and 1,800 calories. To hit their caloric needs for the day and not be in a calorie surplus they would have to consume all of that protein and carbs without a single gram of fat, which is impossible. Something has to give!

With the quick example above we can easily see how endurance athletes in particular can end up with chronically depleted glycogen stores while consuming high protein diets.

Conclusion

There is no exact number, but we can be fairly certain that most athlete's (novice and expert alike) protein requirements fall somewhere between 1.3 g/kg and 1.8 g/kg. Not only that, but consuming far in excess of those numbers can be detrimental to health. More is not always better.

Most novice athletes would benefit more from interventions like increased carb intake, creatine supplementation, and more sleep.