Trick For Evaluating Protein Content

The Rule Of Protein Grams Times Ten

In a recent conversation with my sister, she mentioned to me that a useful rule of thumb for finding if a food was truly helpful to a high-protein diet is to look at the label, take the number of grams of protein in one serving of the food, multiply it by ten, and compare it to the calories per serving.

\[\boxed{\text{grams of protein} \ast 10 \ge \text{calories}?}\]

If the number is greater than or equal to the calories in a serving, that’s a good sign¹, i.e. that food will help you meet your protein target for the day. If it’s lower, that’s a reject.

In the moment, I did some incorrect mental calculations as I tried to figure out why the one number (protein grams) should be in a 1:10 ratio with total calories. This blog post is my effort to untangle my thinking and record why I think this rule of thumb exists.

I want to make it clear that I am not doing a whole diet analysis. I’m trying to evaluate a specific rule of thumb to see whether, why, and when it might make sense. And, as a shortcut, what does it buy me? And I am not citing an authoritative source on this rule of thumb. You may have come across it yourself online, or on social media. I did some searches and found it quoted in some places, and challenged in other places.

I also want to acknowledge that a rule of thumb isn’t meant for precision; it’s meant for speed. Like, when you’re shopping and you pick up a food that claims to be a high-protein snack. It would be nice to be able to evaluate that quickly.

What I Noticed

I happened to notice that my daily protein target was in about a 1:12 ratio with my daily calorie target, and closer to a 1:11 ratio of my recent caloric intake. That made me think “this rule of thumb would probably help me stay on track, at least with what I’ve been eating lately.” Ballparking sometimes tells you whether it’s worth following up on a thought.

So, back to some simple arithmetic.

Hypothetically, let’s assume you’re looking at the label on a 100 calorie snack pack of something. You want to apply the rule of thumb, so you look at the protein grams. It’s got 10 grams of protein. 10 * 10 is 100. It passes the rule of thumb, since 100 is greater than or equal to 100 (total calories per serving in the snack pack).

10g of protein at four calories per gram of protein² means that 40 of those 100 total calories is from protein. In other words, the food is 40% protein calories. So, here we’ve revealed that the rule of thumb is judging a food on whether at least 40% of its energy is coming from protein calories. Interesting!

For myself, I noticed that 40% is above, but not too far from, the the 33% that comes up for my target protein intake based on how I have my tracking app set up. YMMV ³. That makes sense for a diet where I’m trying to make sure I hit my protein total as a priority, and am less concerned about my other macronutrients. In an earlier post I described hitting the protein target like a video game, and I referred to the possibility of eating every meal or food such that you hit your protein target perfectly as you creep up to your calorie target. While it’s unrealistic to expect every food to be perfectly on track (I’m eating veggies and bread, not just meat, fish, and eggs) eating more foods that are at least 40% are going to help me stay ahead of my 33% rate of protein-eating.

You can think of it this way: if I’m trying to scooter from Boston to NYC and I’ve been asked (for some reason) to make the trip at an average pace of 33 MPH, but I have a max speed of 40 MPH, I should travel at that max speed a lot early in the trip, anticipating that I might have to slow down or stop later on. And if I’m ahead of the average rate, I can always voluntarily slow down late in the trip.

This is one way that the rule of thumb made sense to me. In my specific case. It could help keep me ahead of my protein goal.

Should You Use This Rule of Thumb?

This post isn’t about diet advice. I just needed to think aloud about this one rule of thumb. Resolved: this particular rule is helpful for me, a moderately-active person over the age of 50 who has to be concerned with protein intake while cutting calories because of the fear of muscle loss, and the desire to add muscle if possible. The math works out.

If you want to figure out what you should be eating, you should talk to a doctor or nutritionist or dietitian and/or “do your own research.” You can look to recommendations on protein intake from reputable sources. What you might notice is that there is huge variation in the range of healthy protein percentage. The range of 10%-35% is thrown around. Everyone is a little different. And situations are different as well. Apparently different enough that some people are going to need or want more than twice the percentage of protein calories than some other people.

And that’s why the multiply-protein-by-ten rule of thumb isn’t the only one out there. In some places you’ll see people recommending a 1:20 ratio. Quick math: 1:20 is the same relationship as 10:200 and 5:100. That’s only five grams of protein in your 100 calorie snack pack. 5g * 4 cal/gram = 20 calories, which is 20% of 100. Unsurprisingly, that’s half of the rule of thumb from earlier (20% instead of 40%). This tells us that if a person is on the low end of the range of healthy variation of protein intake, for them a helpful guide for a high-protein food could be to multiply the grams by 20. See – it’s going to depend on you.

My sister got her recommendations from a professional, and professionals can give advice that applies to their client or patient’s particular circumstances. Professionals have credentials that help you know they’re trustworthy in their field. Now that I’ve thought about these rules of thumb, I see how they can help me in my current situation. The multiply-protein-by-10 rule is going to help me know “if I eat this food am I getting ahead in my protein goals, or will I have to make up for falling behind?”

As an aside, don’t be afraid to do some arithmetic to verify things you hear, no matter what the source is. That’s why they decided to teach you math!

AI Disclosure: AI results in Google search helped me verify details. Always follow up on sources when a result has any AI involved. All writing on this post is my own.

1. Why would you eat a high-protein diet? It is one way to avoid losing muscle when you happen to be eating a calorie deficit. Like when your are trying to lose weight, for example. Or maintain a healthy weight. Some diets specify hitting a certain number of grams of protein by the end of the day, not just a certain number of calories. ↩

2. Protein supplies four calories of energy per gram. Carbohydrates supply four calories per gram. Fat supplies nine calories per gram. Alcohol supplies seven grams of energy per gram. So be careful with the booze, too. It’s not just the sugar in beer that’ll getcha. ↩

3. You don’t need a tracking app to estimate how many grams of protein you should eat in a day. There are rough guidelines endorsed by reputable sources. ↩