Why does the FDA recommend only 50g of protein for an adult male?

Question

I have seen in a number of places that in order to maintain muscle mass you should eat something like 0.8-1g of protein per pound per day. Like the person in this question, I'm finding that I really have to focus on protein in order to get 160-180g of protein every day - for a 2500 calorie diet, since it's easy for carbs to take up a lot of calories and providing very little in the way of protein (this is not terribly difficult to do, mind you — two scoops of protein powder and a 16 oz container of low-fat cottage cheese gets me 92g of protein in 560 calories, so I just need to average 18% protein for the remaining 2000 calories, I just need to make sure to eat that or some equivalent every day).

However, I noticed the other day that for a 2000 calorie diet the FDA only recommends 50 g of protein! This seems like a huge gap, considering that very few people eating a 2000 calorie diet would weigh only 100 pounds. Is the 0.8-1g/lb recommendation only for people specifically doing weight training? Does the FDA dramatically underestimate the amount of protein people need? Is there some non-linearity here where your muscle mass won't fall below a certain threshold even if you have quite low protein intake?

I'll note that I found this page which seems to point towards a saturation effect where 0.8g/lb is the maximum amount of protein that has any effect on muscle synthesis¹:

I am not quite sure how to interpret this chart, however, since it seems to be gross muscle synthetic rate, not net (though I would guess based on the chart for "sedentary individual" that the baseline muscle protein loss is 20?).

1. Chart from Lemon, P. W., Tarnopolsky, M. A., MacDougall, J. D., & Atkinson, S. A. (1992). Protein requirements and muscle mass/strength changes during intensive training in novice bodybuilders. Journal of applied physiology, 73(2), 767–775. https://doi.org/10.1152/jappl.1992.73.2.767

Answer 1

50 grams of protein is the minimum amount of protein your body needs to not be deficient. These shouldn't be the goals you shoot for. 100 grams is more an appropriate amount to stay healthy. 30g of protein per meal and a snack or two will get you there. A cup of milk can be 8-13g alone, so really as long as you eat cheese, small amounts of meat, eggs, and drink a cup or two of milk a day, you're fine. Eating healthy is actually a lot harder than it looks, whether you're thin or not. For a bodybuilder, add a casein shake at night along with whey protein supplements for working out, and that'll easily add another 90+, giving you the bodybuilder 1G/lb amount. As far as saturation, there was a study I read once (I can't recall the source but I believe Arnold Schwarzenegger cited it) that after eating steak in different amounts, the group that had 30grams of protein had just as much saturation, leading to the already prevalent notion that 30g of protein at once is as much as your body can absorb at a time. That isn't to say if you include the complexity of slow digestion such as casein that takes a lot longer to digest, you can consume more.

Just a side fact, but unless you are working out, you shouldn't rely on protein shakes for your daily needs. You need to get as much protein from your diet as possible. Cottage cheese is a great casein protein to take. Protein supplements are really just for bodybuilding/strength training, they will help on a day when you don't get enough protein in your meals but you should really strive to just include protein from foods in your diet.

Answer 2

The FDA recommendations are a very general guide and refer to the general population, not athletes or anyone doing large amounts of exercise.

The IAAF have recently released some updated nutritional guidelines, the recommendations regarding protein intake are given below, note point 4 in particular:

1. The optimum daily protein intake for weight stable Athletes exceeds the protein RDA (0.8–1.0 g/kg BM/day) set for the general adult population.
2. The optimum daily protein intake for Athletes who have a goal of weight maintenance or weight gain ranges from 1.3 to 1.7 g/kg BM/day.
3. The optimum per meal/serving of protein for Athletes who have a goal of weight maintenance or weight gain ranges from 0.3 to 0.4 g/kg BM/meal.
4. Very high protein intakes of >2.5 g/kg BM/day offer no adaptive advantage.
5. The optimum daily protein intake for Athletes who are undertaking high-quality weight loss exceeds 1.6 g/kg BM/day and may be as high as 2.4 g/kg BM/day.
6. Athletes who consume a high-protein diet (e.g., 2.4 g/kg BM/day) during weight loss are not at increased risk of kidney problems or poor bone health.

Answer 3

Like the person in this question, I'm finding that I really have to focus on protein in order to get 160-180g of protein every day.

You will find that many things in the fitness world are about optimizing everything. It is not essential to consume 160g-180g of protein every day, but reaching your upper level of protein synthesis rate is what will produce the fastest/best results when training. I believe the reason people say .8-1 g/lb is simply because they heard it was slightly above .8 for strength athletes and they believe it is better to get too much than not enough. It doesn't do any harm consuming too much protein for the vast majority of adults (There are a few super rare metabolic disorders that make consuming too much protein dangerous). Every time you eat protein, the liver converts its nitrogen into the compound urea, which the kidneys then process and allow you to excrete from your body through urine. Basically you pee out the excess protein.

I am not quite sure how to interpret this chart

That chart shows the point at which additional protein intake ceases to yield any benefits for different athletes/levels of fitness. As you can see 1.8g/kg (0.82 g/lb) is that point for strength athletes. Endurance athletes are a bit lower at around 1.35 g/kg (0.61 g/lb). Sedentary people are sitting at around 0.9g/kg (0.41 g/lb).

Does the FDA dramatically underestimate the amount of protein people need?

No. As @JustSnilloc and @Ace Cabbie mention, it is how much they are recommending so people remain healthy. It really is a super general number that should be more specific to include weight, sex, and activity levels. The issue is that if advice starts getting complicated, people stop listening so most fitness advice is super generalized. The 0.82 g/lb is for strength athletes who are looking to build muscle. The body will synthesize more protein if you are building muscle.

Answer 4

Everybody above has covered how the FDA only provides guidelines to prevent illness, but in addition to that, remember that "protein" is a very generic category. Proteins are made of amino acids and different proteins have different component amino acids and different ratios of those. Depending on why you need to consume more protein, the type as well as the amount is important. To cover the average case dieticians will take the 'average' protein and average it over the population, but if you need a specific type of amino acid and are eating 'average' protein, your overall protein requirement may be higher than if you are eating targeted proteins.

A good example of this is leucine, an amino acid important for muscle synthesis. The specifics are a popular subject of ongoing investigations, so paying attention to what's going on on Google scholar will give you some information for targeting (as well as samping anecdotal evidence from fitness forums).

You may need a lower overall protein amount if you are eating the optimal type of protein for your needs (and vice-versa).