With companies keen on selling you their protein powders and protein shakes, it is often difficult to know whether nutrition advice on the Internet is grounded in solid research or just a ploy to get more sales. We take a look at the research into using protein for recovery after running and to speed up injury healing. And we weigh in on the debate about natural foods vs. supplements as a source of protein.
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In this article:
How much protein is needed after exercise to best stimulate muscle growth?
Is there any benefit in taking protein supplements during exercise?
Is there a “best time” to ingest protein to help build muscle?
Should you have a high-protein diet when trying to lose weight?
When you're recovering from injury, can a high-protein diet prevent loss of muscle mass?
Are protein supplements better than food sources of protein?
How much protein is needed after exercise to best stimulate muscle growth?
We know that exercise is a potent stimulus to build muscle, but this can only happen if you have the right nutrients available. Your muscles first go through a breakdown phase after exercise and then has to use the proteins that you have eaten during the day to rebuild themselves stronger.
It turns out that the average person only needs about 20 g to 25 g of high-quality protein after an exercise session, but this should be consumed within two hours after exercise to get the most benefit.
If you are a masters athlete (above 50 years of age), you may have to take higher doses of protein to allow your muscles to recover at the same rate as those of your younger self.
This does not have to be in the form of a protein shake or bar. It can simply be whatever protein you are eating with your next meal (see the list below for natural protein sources). This is good news for me, since I really struggle with consuming anything with the word "supplement" in it – I think my brain files it in the same category as medicine 🙃.
The more the better, right? Well, actually no. Researchers have not found any extra benefit if you take greater amounts of protein supplements within that period of time (see the following section for more details on how to use protein supplements throughout the day).
Endurance athletes may be interested to know that protein intake after exercise can also help to increase mitochondrial proteins. Your mitochondria can be seen as the battery boxes of your cells. Eating enough protein after exercise may allow your muscles to become better at using the oxygen that is available to them during your next exercise bout.
Foods and beverages providing 20 g of high-quality protein
You can check the protein content of different food sources on the USDA website. I've calculated the most obvious ones below.
Fluid 1% low-fat milk (plain or flavoured) - 591 ml
Low-fat yogurt (plain) - 454 g
Low-fat Greek style yogurt (plain) - 227 g
Soy milk, plain - 680 ml
Lean beef or pork - 85 g
Lean ground beef patty - 85 g
Poultry - 85 g
Eggs, whole - 3 large
Eggs, white - 6 large
Cheese, cheddar - 85 g
Cheese, low-fat string cheese - 85 g
Cottage cheese - 43 g
Tuna, light canned in water - 85 g
Salmon, farm-raised - 85 g
Broadbeans (raw) - 80 g
Red Kidney beans (raw) - 80 g
Lentils (raw) - 85 g
Is there any benefit in taking protein supplements during exercise?
Not unless you are an endurance athlete! Research has shown that athletes are unlikely to experience performance benefits from consuming protein during events. However, they may recover better if they consume protein during events that are longer than three to five hours.
Ultra-endurance athletes may be less able to digest and absorb protein after exercise of this duration, because of the blood being shunted away from the gut to the muscles. Taking on some protein during endurance events can help them reach the optimal levels within the right time frame and may thus hold an advantage for their recovery, especially in multi-day events.
Protein supplements may be a better choice in these situations, because they are easier to digest.
Is there a “best time” to ingest protein to help build muscle?
The current research seems to suggest that:
The average person should aim to consume about 30 g of high-quality protein in five small meals,
or if you're not average size, 2.5 g per kilogram of bodyweight, divided by 5,
spaced evenly throughout the day to get the most benefit.
💡Researchers have also found that consuming an additional 40 g of protein before bedtime allows your body to continue building muscle while you sleep.
If you are over the age of 55, you may have to follow a slightly different approach. Older athletes require more protein and should take it at different times to get the same benefits as younger athletes.
What is the best source of protein for athletes?
When you eat protein, your stomach and gut break it down into various amino acids (the basic building blocks of protein). Your body then uses these amino acids to form your own muscle proteins.
So, it makes sense that the best protein to eat is that which provides all the essential amino acids.
The research has shown that:
Milk protein may have the advantage over single-source proteins, like soy, because milk contains both whey and casein.
Whey protein appears to be more effective than casein alone.
Soy is slightly less effective than whey.
Whey protein’s superior effect is thought to be due to the amino acid leucine (1.8 g of leucine post-exercise appears to get the best results). Do take care when you buy whey protein, since not all preparations contain the same amount of protein.
Milk is a good natural source if you don't like supplements — 600 ml of the white liquid not only contains 20 g of protein (whey and casein) and plenty of leucine, but also other vitamins and minerals that your body needs.
But maybe you do prefer taking supplements instead. I've rummaged around on Amazon and found these protein supplement options from brands that look trustworthy. Of course, you are responsible for what you buy in the final instance.
Should you have a high-protein diet when trying to lose weight?
The short answer is yes, but as usual, it is a bit more complicated than that. It may really be worth discussing your diet and exercise volume with a dietitian to get the best results.
If you want to preserve your lean muscle mass while enhancing fat loss, the research suggests the following regime:
A 500 calorie deficit per day. This means that you should work out how many calories you burn with exercise and normal activities per day, and your total daily intake should be 500 less.
Eat 1.8 g to 2.7 g of protein per kilogram of bodyweight per day (or at the higher end of the Acceptable Macronutrient Distribution range of 30% to 35%).
30% of your calories should come from fat and the remainder from carbohydrates (total calories minus calories from protein minus calories from fat = how much carbs you should eat).
And finally, combine this diet with resistance training.
When you're recovering from injury, can a high-protein diet prevent loss of muscle mass?
Remember that you need a combination of exercise and enough protein in your diet to gain muscle mass.
Exercise + Protein = More Muscle
Unfortunately, this means that you will lose muscle mass if you cannot exercise that muscle, despite eating adequate amounts of protein.
You may be worried about getting fat when you can’t train and therefore restrict your calories during injury. Your body can, however, only repair if you actually provide it with all the nutrients it requires to get the job done.
While consuming protein will not prevent muscle loss, it still plays an important role in your healing and recovery. The research suggests that you should aim for 1.6 g to 2.5 g protein per kilogram of bodyweight, spaced evenly throughout 4 to 6 feedings a day.
And all is not lost! There may be a way of getting the "exercise" component done without causing further harm. Neuromuscular electrical stimulation (NMES) is a very effective tool that we use in practice to exercise muscles when the joints, ligaments, or tendons do not allow us to do traditional strength training.
Many clinics use the Compex machines. They are small and portable and stimulate strong muscle contractions that produce the same results you get from lifting weights, but with no pressure or force in the joints or ligaments.
👉 If you are worried about losing muscle mass while injured, my advice would be to:
Eat adequate amounts of protein.
Get a Compex machine to exercise the muscles around your injured body part.
Continue your strength training programme for the rest of your body as normal.
Here's a selection of NMES units on Amazon. Or you can go to the Compex Store.
Protein intake and your immune system
A high-protein diet (3 g per kilogram of bodyweight per day) for athletes has been shown to help restore their immune systems after training.
Athletes who undergo high volumes / intense training programmes reported fewer upper respiratory illnesses (head colds, coughs, and sinus infections) when they ate high amounts of protein daily.
Are protein supplements better than food sources of protein?
There is no evidence that protein supplements are superior to food sources.
Using protein powders and bars may be more convenient than lugging food around, but it is important to realise that protein supplements are not regulated by the likes of the US Food and Drug Administration.
Some of these products have been shown to:
not contain the active ingredients stated on the label;
contain harmful substances, including toxic agents and prescription-only pharmaceuticals;
In 2021 and 2022, a group of Spanish researchers bought 47 different whey protein supplements online and from pharmacies, gyms, sports stores, and supermarkets. They compared the actual protein content of each and compared this to what was claimed on the label. The average actual protein content was 70.9% and the average claimed content was 74.3%. However, eight of these supplements had more protein than what the label said. (Unfortunately, the authors didn't name and shame the products in their report.)
Another advantage of getting your proteins through regular food is that many foods also contain other essential nutrients that aren't present in supplements. Eggs, for instance, contain Vitamin D, which is essential for healthy bones and muscles.
My advice would be to eat whole foods most of the time, and if you do buy protein supplements, shakes, and bars, go for reputable brands.
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About the Author
Maryke Louw is a chartered physiotherapist with more than 15 years' experience and a Masters Degree in Sports Injury Management. Follow her on LinkedIn and ResearchGate.