How To Get Enough Protein From Plants
It’s easier than you think.
The secret to effortlessly getting enough protein from plants lies in balancing your diet using relative protein content.
What is relative protein content
Relative protein content tells you how much of the energy provided by a food comes from protein (rather than fat or carbohydrates). You can calculate percent of calories from protein using grams of protein and calorie content.
This is a great way to compare foods because it doesn’t depend on serving sizes. Methods that compare different foods using mass (e.g. per 100 grams) or by volume (e.g. per cup cups), penalize foods with high water and fiber content. Methods that use “typical” serving sizes are far too arbitrary.
Example: A protein bar with 20 grams of protein in 240 calories
20 grams protein x 4 calories per gram* = 80 calories; 80 calories / 240 calories = 33%.
Get to know the protein landscape
The chart below shows the protein content by of 20 plant-based foods compared to 5 meats and 5 dairy products.
Foods are compared using protein content relative to total calories. Grams of protein per 100 calories is shown on the left, and percent of calories from protein is shown on the right.
If you’re surprised by the high protein content of plant-based foods, think like a biologist! Every cell in every living organism, whether plant or animal, needs proteins to live. If you are eating a whole organism, it will contain ample relative protein.
It’s a different story when we eat specialized organs. For example, root vegetables, like potatoes and carrots, are energy storage organs for plants (think glycogen in your liver), whereas fruits are the seed-bearing organs of plants (think ovaries!), and are loaded with sugars.
What about processed foods?
Processed foods vary greatly in protein content. Many classical “junk foods” like chips or baked goods are low in protein, and contain mostly refined carbohydrates and fats. Processed foods marketed as “high protein” — like veggie meats and protein bars are an exception (thanks to added protein) and tend to land in the same range as my “above target” veggies. Protein powders, not surprisingly, are very rich in protein, with 80% of calories or more from protein. See Appendix for more examples of processed foods.
Fun fact: Protein bars having nothing on whole foods. An average protein bar has around 33% of calories from protein. This is the same as soy milk, tofu, and edamame.
Group foods relative to your protein target
Once you understand the landscape, you can group foods based on how they fall relative to your protein target.
How much protein do you need?
Protein targets range greatly depending on age, activity and goals. While 10% is enough for most people to meet basic maintenance needs, there are a variety of contexts in which up to double this amount may be better. Personally, I aim for 12–20% of calories from protein depending on my activities and physique goals. To set a protein target for your child, check out this related article.
Since protein goals are often given using grams per kilogram bodyweight, it can be useful to know how to convert this to a percentage.
Example 1: Standard RDA (0.8 grams /kg) for a 60 kg adult.
60 kg adult x 0.8 kg/day = 48 kg protein per day (60 x 0.8 g/kg).
This is 192 calories (48 grams x 4 grams per kg). 192 protein cals/ 1800 cals per day = 11%.
As you can see in this example, the standard RDA works out to about 11% of calories for a 60 kg adult eating a moderate calorie diet. If this same adult wanted to hit 1.6 g/kg (a common target for bodybuilding) they would need to average around 20% of calories from protein.
Use your protein bins
This is how I put my protein bins to use to meet my target of roughly 15%:
- Eat some foods from my “above target” bins:
- Above Target (25%-45%): Beans and legumes (Soy/tofu/edamame, black beans, lentils, peas), cruciferous veggies (cauliflower, broccoli), leafy greens
2. Eat as much as I want from my “on target” bin:
- On Target (12–18%): Nuts, seeds, whole grains (e.g. quinoa, oats, buckwheat)
3. Moderate intake from my below-target bin — balancing this with my “above target” bins:
- Below Target (4–11%): fruits, starchy vegetables (root veg), rice
- Nada (0%): Fats (olive oil, butter)
- High-fat and high-carb processed foods (baked goods, ice cream, fried foods)
Note: The rolling average over multiple days is what matters most, so you can balance a lower protein day with a higher protein day.
Of course, calorie density does matter. Even though leafy greens have a very high percent of protein, it’s impossible to eat enough of them to fuel your body. Thus, it’s the protein content of your heartier foods that matters most.
Closing Thoughts
Plants are surprisingly rich in protein. As long as you balance your intake of those in the low protein bin with the high protein bin, you can meet your target without counting. Soon enough, you’ll naturally build balanced meals.
In general, the higher you go, the slimmer your choices, and the more foods you need to limit. It’s up to you to decide if it’s worth it!
Learn more about the art and science of healthy eating on my website at https://fueledbyscience.com
The viewpoint presented here is my personal perspective based on my review of the scientific literature and should not be seen as medical advice.
Limitations
The protein content figures presented here are not corrected for measures of protein quality including protein absorption. These numbers tend to be higher in animal sources than plant-sources, but not significantly enough to change the overall message. This nuance is on my list of future topics!
Related Articles
- Your Child May Not Need as Much Protein as You Think — shows you how to calculate your child’s protein needs ( in grams and percent of calories)
- Busting the Myth of Incomplete Plant-Based Proteins — compares protein quality between plant and animal proteins.
- Beef Versus Broccoli: Making an Apples-To-Apples Comparison — compares the amount of protein in broccoli and beef using five different method and sheds light on how to be a more critical nutrition research consumer
Appendix
Protein target ranges
- World Health Organization — minimum recommendations fall below 10% of calories in some cases (depending on age and activity level). Tends to be lower for children because of high energy (calorie) needs.
- Health Canada (10–35% of calories)
Protein Content of Whole Food Groups
- Meats (30–60%) — Meats ‘own’ the top spot for protein content but many dairy and plant-based foods aren’t far behind. Note: Some fatty meats punch in much lower than the typical meats — e.g. bacon comes in at about 12% of calories, similar to whole grains.
- Dairy (20–35%) — Most dairy products are high in protein, just behind meats. Ultra fatty versions like cream cheese are an exception.
- Vegetables (20%–35%) — Protein content for veggies is surprisingly high, with the exception of the root vegetables mentioned above. Generous servings are key as these tend to be lower in calories.
Your best veggie bets are beans (black beans, kidney beans) other legumes (tofu, edamame, lentils, peas), leafy greens, brassica vegetables (cauliflower, broccoli).
4. Seeds & Nuts (~15%) — You may be surprised that seeds and nuts are not higher in my scorecard, but their high fat content bumps them down the relative protein meter.
5. Whole grains (~12%) — With the exception of brown rice, most other WHOLE grains boast more than 10% of calories from protein (e.g. quinoa, oats, buckwheat).
6. Starchy vegetables and rice (8–12%) — Carrots, potatoes, yams, white and brown rice.
7. Fruits (3–6%) *— Fruits largely just provide sugars, with no fat and very little protein. Berries score slightly higher than others.
8. Fats (0–2%) — Butter, olive oil, vegetable oil, coconut oil
*Note: I used a culinary definition of fruits (sweet part of a plant), not a botanical one (according to a botanist, seeds, nuts and some veggies are also fruits). Protein levels in these “pseudo-fruits” are a mixed bag (keep reading).
Protein Content of Processed Foods
These examples illustrate the variable protein content of processed foods:
- Protein bars: ~ 20%-35% of calories (e.g. bars from Luna, Kellogg, Clif, Power, Kirkland).
- Granola bars: ~10% of calories (e.g. Nature’s Valley, most Kind bars)
- Crackers: ~6% of calories (e.g. Wheat Thins original)
- Muffins: ~6% of calories (e.g. My husband’s fave: Starbuck’s lowfat blueberry muffin)
- Ice cream:~6% of calories (e.g. Hagen Dazs vanilla)
