What can I add to oats to make a complete protein? The definitive guide

October 7, 2025 •

4 min read

A single serving of oats, while rich in fiber and other nutrients, is considered an incomplete protein source, lacking sufficient levels of the essential amino acid lysine. Knowing what can I add to oats to make a complete protein is crucial for building a more balanced and muscle-supporting morning meal.

Quick Summary

Oats, an incomplete protein, can become complete by adding complementary foods containing the missing amino acid, lysine. Dairy, eggs, legumes, nuts, seeds, and protein powders are all effective options for boosting the protein profile of your breakfast.

Key Points

Combine with Dairy: Mixing Greek yogurt, cottage cheese, or milk into oatmeal adds high-quality, complete protein from animal sources.
Use Legumes: For a plant-based solution, add peanut butter or soy milk, which are derived from legumes and help fill the lysine gap in oats.
Add Seeds and Nuts: Hemp seeds are a complete protein, while chia, pumpkin, and almonds also provide essential amino acids to complement oats.
Incorporate Protein Powder: Whey or plant-based protein powders are a fast, effective way to significantly increase the complete protein content of your oats.
Don't Stress about Timing: The body can combine complementary proteins throughout the day, so achieving a complete profile doesn't require all components in a single meal.
Consider Savory Options: Don't limit yourself to sweet preparations; savory oatmeal with eggs and cheese offers a protein-rich and flavorful alternative.

Understanding Complete vs. Incomplete Proteins

Proteins are fundamental building blocks for our bodies, composed of smaller units called amino acids. Of the 20 total amino acids, nine are considered “essential,” meaning our bodies cannot produce them and we must obtain them through our diet. A “complete protein” is a food source that contains all nine essential amino acids in adequate amounts. Oats, like most grains, are an “incomplete protein” because they are relatively low in lysine.

However, it is a common misconception that all essential amino acids must be consumed in the same meal. Instead, health experts emphasize that getting a variety of protein sources throughout the day is what matters most. For those who prefer to complete the protein profile within a single breakfast, there are many simple and delicious additions.

Dairy and Egg Additions for a Complete Protein

Animal-based products are excellent sources of complete protein, making them a straightforward choice for balancing your oatmeal.

Greek Yogurt or Cottage Cheese: Stirring a half-cup of Greek yogurt or cottage cheese into your warm or overnight oats instantly elevates the protein content significantly. Cottage cheese, for example, can add around 12 grams of high-quality protein per serving. This creates a creamy, rich texture reminiscent of cheesecake.
Milk (Dairy): Opting to cook your oats with dairy milk instead of water is an effortless way to increase the protein. A single cup of milk adds around 8 grams of protein.
Eggs: For a savory twist, eggs are a complete protein powerhouse. Whisking an egg or two into your oats while they cook creates a thick, custard-like porridge. To avoid scrambling, keep the heat low and stir constantly. Savory oatmeal with eggs, cheese, and vegetables is a delicious alternative to a sweet breakfast.

Plant-Based Combinations for a Complete Protein

For vegans and vegetarians, combining specific plant-based foods can create a complete protein. The key is to pair grains with legumes, nuts, or seeds.

Nuts and Seeds: A simple sprinkle of nuts or seeds is a popular option. Hemp seeds are a standalone complete protein and offer about 9.45 grams per three tablespoons, while pumpkin seeds pack 10 grams per quarter-cup. Adding nuts like almonds or peanuts provides a lysine boost and healthy fats.
Legumes: Peanut butter, derived from a legume, is a classic partner for oats. Two tablespoons can add around 7-8 grams of protein. For a less common, but effective, approach, white beans can be mashed and stirred into oats for a neutral flavor and significant protein addition. Soy milk is another potent legume-based option, offering similar protein content to dairy milk.
Quinoa: A unique grain that is a complete protein by itself, quinoa can be cooked with oats to naturally create a complete amino acid profile.

Adding Protein Powders

Protein powders offer a convenient and customizable method for boosting the amino acid profile of oatmeal, especially for athletes or those with high protein targets.

Whey Protein: Derived from milk, whey is a complete protein and highly effective for muscle repair. To prevent clumping, stir the powder in after the oats have cooked and slightly cooled, or pre-mix it with a little water or milk.
Plant-Based Protein Powders: Vegan-friendly powders made from pea, hemp, or soy protein are widely available. These are also complete protein sources that can be stirred into cooked oats or added to overnight oats.

Comparison of Common Oatmeal Protein Additions


Protein Addition	Protein per Serving (approx.)	Vegan-Friendly?	Notes/Best For
Greek Yogurt (1/2 cup)	~12g	No	Creamy texture, tangy flavor. Ideal for overnight oats.
Cottage Cheese (1/2 cup)	~12g	No	Smooth texture when blended. Pairs well with sweet or savory.
Protein Powder (1 scoop)	~20-30g	Yes (plant-based) / No (whey)	High protein boost, customizable flavors. Mix carefully to avoid clumps.
Peanut Butter (2 tbsp)	~7-8g	Yes	Adds rich flavor and healthy fats. Good for sweet oats.
Hemp Seeds (3 tbsp)	~9.5g	Yes	Neutral, nutty flavor. Good source of omega-3s.
Quinoa (1/4 cup)	~4g	Yes	Grain addition that completes the protein. Adds texture.
Eggs (2 whole)	~12g	No	Perfect for savory oatmeal. Creates a creamy, custard-like result.

Combining for Culinary Creativity

To keep your meals interesting, mix and match your protein sources. For instance, combine a couple of tablespoons of peanut butter with a sprinkle of chia seeds for a double protein punch and improved amino acid variety. For a creamy and savory bowl, mix in cottage cheese and top with sautéed mushrooms and a fried egg. Experimenting with different combinations ensures you not only get a complete protein but also enjoy a wide range of flavors and textures.

Conclusion

While oats alone are not a complete protein due to their lower lysine content, this is easily remedied with strategic additions. From incorporating dairy products like Greek yogurt or cottage cheese to plant-based options like nuts, seeds, and legumes, achieving a complete protein profile is simple. For maximum protein impact, especially for fitness goals, protein powders offer a convenient boost. The key takeaway is that with a bit of variety, your daily bowl of oatmeal can be transformed from a good breakfast into a nutritionally complete powerhouse.

Visit the Cleveland Clinic's health page for more information on complete vs. incomplete proteins.

Frequently Asked Questions

Yes, oats are considered an incomplete protein. While they contain all nine essential amino acids, they have insufficient levels of lysine, which means they must be complemented with other foods to form a complete protein.

One of the easiest methods is to stir in a scoop of protein powder (whey or plant-based) or a half-cup of Greek yogurt or cottage cheese after cooking.

For a vegan complete protein, combine oats with legumes, seeds, and nuts. Good options include adding peanut butter, soy milk, hemp seeds, chia seeds, or plant-based protein powder.

No, you don't need to combine complementary proteins in the same meal. The body can effectively use amino acids from different foods eaten throughout the day to form complete proteins.

To avoid a clumpy texture, stir the protein powder in after the oats have finished cooking and have cooled slightly. For the smoothest result, mix the powder with a little liquid first to create a paste before adding it to your oatmeal.

Yes, you can add eggs to your oatmeal for a savory, high-protein meal. Whisk one or two eggs into the oats while they cook over low heat, stirring continuously to create a creamy, thick texture.

Overnight oats can be made a complete protein by mixing in high-protein ingredients like Greek yogurt, cottage cheese, protein powder, or seeds like chia and hemp before refrigerating.