🥙 Nutrition

Animal Food Sources: The Need for Complete Protein in Your Diet

UPDATED ON Jul 12, 2022

The human body needs protein: it forms an essential cornerstone of our diets. Its functions are varied and include the maintenance and repair of the body’s structures (muscle mass, soft tissue, organs, hair and so on) as well as the building of new tissue.

As the human body cannot store protein in the way that it can the other two macronutrients- carbohydrates and fat- we need to take it in regular supply through our diets.

Beautiful fitness girl posing
Our bodies rely on protein for structure. Photo: Etoilestars / Adobe Stock

But where should this protein come from? A debate surrounds protein sources, and I’ll be looking at one particular area today: the necessity of taking in protein from animal sources, rather than relying on plant sources.

different protein food sources
Protein sources come in many shapes and sizes. Photo: nehopelon / Adobe Stock

Appreciating and understanding the differences between animal protein sources and plant ones is vital for anybody looking to optimise their diet, as well as for anybody wanting to maximise their athletic potential. Which is better for recovery after training; which is better for hypertrophy; and which is better for overall health?

I’ll answer all of these below.


Proteins consist of amino acids, and the human body needs a complete complement of all 22 types of amino acid in order to function optimally. As the building blocks of protein, these amino acids play a central role in protein’s dietary use. When the body ingests protein, it breaks it down into these amino acids and will use them at different times, to serve different purposes.

Of these acids, 9 cannot be produced by the human body: these are essential amino acids.

It’s widely believed in fitness circles that your diet should include complete sources of protein, which contain all of these essential amino acids: to maximise athletic performance, hypertrophy, health and recovery, you need to make sure that you’re getting adequate supplies of all of them.

healthy lifestyle, culinary, cooking and diet concept - close up of red meat fillets and boiled eggs on wooden table
Animal sources like eggs and meat give a complete source of protein. Photo: Syda Productions / Adobe Stock

Plant vs. animal protein sources

Barring a couple of poor-quality examples, complete protein sources are only ever derived from animal sources. These include meat, most obviously, alongside eggs and dairy products.

The lack of complete protein from plant based-sources is perhaps the key difference between them and animal protein sources.

Popular sources of complete protein include:

  • fish
  • eggs
  • dairy products like whey, cheese and milk
  • red meat in the form of beef, pork and venison
  • white meat from poultry sources like chicken and turkey
Grilled salmon with spinach, lemon and thyme
Oily fish is one of the best sources of complete protein you can find. Photo: Tiramisu Studio / Adobe Stock

There are a couple of plant-based foods that are complete protein sources. Grains such as quinoa and buckwheat are two of the most popular forms. However, they don’t give great volume, especially compared to foods like meat and whey.

Other plant sources are incomplete. This isn’t an issue in itself, as a mix and match approach to the structuring of your diet can provide complete sources: for this reason, it’s crucial for those on plant-based diets to include a great deal of variety to make sure they’re getting the full array of essential amino acids that they need.

Good quality plant-based protein sources that vegans and vegetarians can mix and match include:

  • grains, pulses and lentils
  • nuts
  • beans and legumes
  • soy
  • hemp
  • rice
  • peas

However, it’s a lot easier and more efficient to take a large portion of your protein intake from animal sources.

Healthy plant vegan food, veggie protein sources: Tofu, vegan milk, beans, lentils, nuts, soy milk, spinach and seeds. Old wooden background copy space
Plant-based protein sources can be combined to give you a full complement of amino acids. Photo: ricka_kinamoto / Adobe Stock

As mentioned above, volume as well as completeness may also be an issue. Compare a regular egg, at 60 calories and 6 grams of protein, with half a tin of baked beans, at 155 calories for 6 grams. You need more than twice the calories from beans to achieve the same protein level as you would get with eggs: the rest is made up of carbohydrates, which may not meet your dietary goals. Similarly, nuts contain a great deal of fat and peas bring a lot of sugar- there are no plant-based foods that really isolate protein, so you will need to eat a high calorie diet (or supplement heavily) in order to meet a high protein demand.

Roasted peanuts in wooden bowl putting on linen and wooden background.
There is more fat than protein here. Photo: thatpichai / Adobe Stock

Plant vs animal sources: which is better for your overall health?

This is where things get a little more complicated, as plant-based sources of protein do generally bring about a greater range of health benefits than animal ones do.

For example, I mentioned above that plant-based protein sources are rarely that high in protein- they give you a lot else besides in the form of extra carbs and fat. Though this makes them more calorific, it also means that you will often get a healthy dose of fibre. Fibre is crucial for good digestion, healthy stomach bacteria levels, and healthy cholesterol levels.

Healthy couple jogging in nature in good spirit
You need protein sources from both sides for full body, holistic health and peak fitness. Photo: nd3000 / Adobe Stock

Plant-based foods also often bring plant-specific micronutrients. These include phytonutrients and certain antioxidants that are missing in animal proteins. Plant-based proteins are also free from the types of saturated fats often present in some meat products.

Eating more plant- rather than animal-based proteins can also lead to improved signifiers in various forms of health, including a decreased risk of cardiovascular disease, increased LDL (‘good’) cholesterol and decreased HDL (‘bad’) cholesterol, lowered blood pressure and often lowered sodium levels.

Steak (Rindfleisch)
Lean meat alone is perfectly healthy and brings a range of athletic benefits. Photo: karepa / Adobe Stock

However, high meat diets alone often do little to affect health: generally, the ill effects need to be combined with another risk factor, such as increased low-quality fat intake, fatty meat consumption (as opposed to lean meat or oily fish), smoking, drinking, and eating processed, high sugar and high sodium foods.

In addition, some sources of animal protein give high levels of vitamin B-12 and iron, in which plant-based foods and hence vegetarian and vegan diets are often deficient.

Which is better for hypertrophy and athletic performance?

Athletes and barbell aficionados often go for whey protein- it makes up around 40-50% of my daily consumption, in the form of shakes. If you’re looking to efficiently metabolise a good quality, complete protein source, it’s amongst the best: for hypertrophy or recovery, there is a good reason it’s so popular.

Some research points to rice protein isolate as a potential challenger, however. It is likely that it offers similar benefits to whey protein. Of course, it is not a complete protein, and so you will need to plug the gaps with the missing amino acids from elsewhere.

Either way, there are two good options available to you.

You can either take the majority of your protein from animal sources and rest assured that you’re getting a full array of amino acids. It’s easy to do, cheap if you make use of whey powder, and will allow you to structure your diet with ease.

For variety, or for an alternative, then plant-based protein is a viable option. You just need to plan a bit more carefully, supplement a bit more fully, and keep everything varied.

How do I structure my protein intake?

One school of thought that is gaining traction at the moment is that protein total is more important than type: as long as you hit enough (which, for me, is most often somewhere in the top 100s) then the rest shouldn’t be too significant.

This leaves a range of things to take into consideration: amount, variety, other benefits you get with your servings. For this reason, I try to follow a varied, high-protein structure.

For sheer convenience and the efficiency of its use, I drink a lot of whey protein (70-100g daily, of which I drink 40-60g during workouts.) I also eat a lot of eggs, which give me a great deal of complete protein and healthy fat, and make use of high-protein, Skyr yoghurt.

Sports nutrition, fitness diet and food concept - protein shake powder on grey background
Whey shakes are a godsend for convenience and volume. Photo: murziknata / Adobe Stock

To keep my digestive health on point, I also go for high-fibre plant-based protein sources. I eat lots of lentils (Indian dal is one of my favourites) and lots of beans (at 40g of mixed protein, beans on toast with a couple of poached eggs is the king of breakfasts, period!) I also eat lots of green, leafy vegetables. Whilst these are predominantly sources of carbs and fibre, and I treat them as such, up to 15g of protein per day can come from them.

It all adds up. It’s simple enough, healthy to follow, and gives me everything I need to make the gains I want from the gym, keep my energy levels up the rest of the time, and make sure that my health remains intact.

James Dixon
James Dixon
James Dixon is a fully qualified personal trainer, with a decade’s worth of experience under his belt. Throughout his career, he has helped hundreds of people to meet their dietary and fitness goals, writing exercise and nutrition plans to suit any and every requirement.
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James Dixon
James Dixon
James Dixon is a fully qualified personal trainer, with a decade’s worth of experience under his belt. Throughout his career, he has helped hundreds of people to meet their dietary and fitness goals, writing exercise and nutrition plans to suit any and every requirement.
Have a question? Contact us