Status: I spent about 30 minutes on this, and looked for authoritative mainstream sources. I would be excited to be proved substantially wrong, but it seems unlikely to me.
There are two factors here: how much do you need, and how much is in typical foods. I think most people have only a hazy idea of the first, and vastly underestimate the latter.
So I need 50 - 100 grams of protein per day. As an active runner and cyclist, but not a lifter and very far from an elite body builder, I plausibly need somewhere in the middle of that range. More likely around 60 grams per day.
Takeaway: depending on your activity level, you can probably multiply your weight in kg by 1, and that’s how many grams of protein you need. If you’re very, very active, multiply it by 1.5. If you’re a lifter and trying to gain a lot of muscle mass, multiply it by 1.8.
I’m not vegetarian, but I am a little-tarian. I eat no beef or pork unless it’s about to be thrown away, and very little chicken or fish. Anyone on this side of the carnivore scale will be familiar with having to defend their ability to survive without the blessing of protein-packed animal flesh.
I downloaded an app called Calorie Counter. Given my vital stats, it said I need around 2150 calories per day, which seems about right.
I entered my meals from today[1] , which was pretty typical:
This came to about 2100 calories. And… drumroll… 68 grams of protein! So on a day where I didn’t eat anything particularly interesting, and didn’t even eat quite enough calories, I still got enough protein to achieve maximum performance as an elite endurance athlete.
I tried entering a super boring day of food, 2150 calories worth of:
And it still came to 52 grams of protein. Comfortably over the RDA, though not quite up to the athlete-y numbers. In reality, I would sprinkle some cheese on the potatoes, have some peanut butter at some point in the day, etc. It only takes two slices of peanut butter on toast to get this day into elite athlete territory.
Takeaway: There’s protein all around us. If you eat a healthy diet that contains interesting (i.e. includes some amount of dairy, or dairy substitutes, or nuts or eggs or beans or…) vegetarian-ish food, or any amount of meaty food, you’re probably getting enough.
The key points are that you don’t need that much protein, and that most foods already have a lot. And because calorie requirements and protein requirements are basically functions of the same thing (age, weight, activity), we can combine these two observations into some simple numbers.
For my specific age (32) and activity level (active), I have the following:
From which it follows that my food should, on average, have 2.6 grams of protein per 100 calories.
If, instead, you’re 25, 180cm tall, weigh 75 kg, and are trying to become a pro body builder, your numbers above would be:
Resulting in a requirement of 4 grams protein per 100 calories.
So how much protein is in 100 calories of some typical foods?
Takeaway: in a very narrow sense, pasta is sufficiently proteiny for all but the gainiest of gains.
[1] go back Actually some day in March that I had recorded.