Plant protein vs. animal protein: Which one is healthier for you?

Increasing your protein intake can provide many health benefits, including weight loss, better body composition, improved blood sugar control, and higher satiety, to name a few.

However, not all protein sources are the same. Animal and plant proteins differ significantly in many ways. Does it matter whether or not you choose animal- or plant-based proteins? In this guide, we will explore that question and the latest available data.

As with all of our guides, Diet Doctor wants to equip you with science-based information and suggestions and then empower you to make your own informed decisions. If you follow our tips and suggestions in this guide, we believe that you will have no trouble meeting your protein needs with either animal or plant proteins, or even a mix of both, depending on your lifestyle.

What is a complete protein?

You may have heard various foods categorized as a “complete protein” or an “incomplete protein.” What exactly does that mean?

After you eat protein-containing foods, your body breaks down the protein into amino acids – the “building blocks” of protein. Of the 20 amino acids found in protein, your body can make 11 of them. The other nine are essential, meaning that they must come from your diet because your body can’t produce them.

Fortunately, protein from animals is “complete,” providing all of the essential amino acids in amounts that your body needs. However, plant proteins (with the exception of soy) are “incomplete” because they lack sufficient amounts of one or more essential amino acids.

That doesn’t mean you can’t meet your protein needs from plants. You simply have to mix and match to make up for the amino acids that are in short supply. For example, you can pair legumes, such as beans or peas (which are high in the amino acid lysine but low in methionine), with grains that are high in methionine but low in lysine. Barley and lentil soup is a popular example of this pairing.

Alternatively, you can combine beans with nuts and seeds, have hummus with whole grain pita, or make the classic rice with beans combination.

Carb-heavy combinations like these aren’t a good fit for a low-carb diet, but if you are less strict with carb intake, they can provide all of the essential amino acids.

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Carb and calorie content

Plant sources of protein tend to be higher in carbohydrates and calories than the equivalent amount of protein from animal sources. If you follow a very low-carb or keto diet, you may find it challenging to meet your dietary goals if you use plants as your only source of protein.

Our protein table shows the number of calories required to obtain 25 grams of protein. As you can see, you can eat 25 grams of protein from beef at a fraction of the calories that you would get from quinoa, peanut butter, or black beans if you ate enough of each to get 25 grams of protein.

Your serving of beef also has zero carbs, whereas your quinoa comes with 126 grams and black beans with 68 grams.

If you want to keep your net carb intake below 20 or 50 grams per day and keep your calorie content as low as possible, plant sources may not be a realistic option. However, if your carb and calorie intake are more liberal, then plant sources may be a good choice.

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Bioavailability/absorption

On average, your body absorbs animal-based protein better than plant-based protein. Soy is once again the exception and is equivalent to animal sources.

The practical implication is that you may need to eat 20-50% more plant proteins to absorb the equivalent amount of amino acids as you would from animal sources.

That doesn’t mean you can’t meet your goals with mostly plant proteins. You absolutely can, particularly if you prioritize soy intake. However, you need to watch the associated carbs and calories that come with the higher-required volume of food if you are trying to lose weight.

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Anabolic or muscle-building benefits