Simplifying the Formula – How Much Protein Do Ultra Endurance Athletes Really Need?
- Sep 15, 2025
- 6 min read
Lauren Callahan is nutrition coach, ultra endurance athlete, and doctoral student. As the founder of Ultra Nutrition, she helps athletes go from injured and tired to resilient and unstoppable through compassionate coaching and plant-forward nutrition.
If you’re anything like me, you can get lost in the numbers. Which is why, as an ultra endurance athlete, my eyes roll to the back of my head when I hear something like, You need 1.2 grams of protein per kg of body weight per day for optimal protein synthesis. I don’t usually use kilograms, and 1.2 doesn’t make for easy math. Do I just need to go have a protein shake and hope it’s working like the ad says it will?
The key to athletic recovery
Knowing what you need as an athlete to properly fuel your training, health, recovery, immunity, and mood can be confusing. Protein in particular is often treated like the holy grail of sports nutrition. But how much do ultra endurance athletes actually need, and how and when should they get it? We’ll break this down in a simple, practical way. But first, let’s remind ourselves why this macronutrient is so important in the first place.
Beyond muscle protein synthesis
While carbohydrates are truly our body’s preferred energy source, protein is still the building block of our muscles, tissues, and enzymes. Most athletes are familiar with the stress and microdamage to muscles after a hard training session, with a subsequent need for repair and recovery. But even beyond that, protein is important for proper immune support and resilience, especially as high-intensity training can temporarily suppress the immune system. Furthermore, proteins play a major role in hormone and enzyme production. In fact, most enzymes are proteins, and they are crucial for energy metabolism, stress response, and overall performance.
Where should ultra endurance athletes get their protein from?
Good marketing antics can lead us to believe that protein shakes, protein bars, and even ultra-processed foods with added protein are exactly what athletes need to supply every protein requirement. But there is a cost to this. The more obvious one is that ultra-processed foods lack the nutrient quality and healthfulness that whole foods offer. While the convenience of a protein-fortified granola bar may be tempting, it simply does not have the “food matrix” of micronutrients, fiber, and healthy carbs and fats that support overall health. And they are often riddled with refined sugars and additives that work against our pursuit of optimal health and performance.
But there is a less obvious cost as well. Protein shakes, which involve isolating protein from that healthy “food matrix,” cause certain amino acids to get lost in the shuffle. Amino acids are the building blocks of protein, and studies show that some, such as the amino acid tryptophan, do not get absorbed as well when we rely on protein shakes for our protein needs. Why is this a problem? Tryptophan is actually a precursor to serotonin (the neurotransmitter associated with a happy mood), melatonin (a hormone responsible for your ability to fall asleep), and the initiation of digestion (which ultimately leads to your ability to efficiently use food for energy).
Another way to say this is that relying on too many protein shakes can make you moody, tired, and slow. Protein shakes have their place, and can be a great way to fill in the gaps occasionally, but they shouldn’t be a primary source of protein.
The meat vs. Plant debate
If you’re getting protein from whole foods, should you focus on animal or plant protein sources? Can plants even provide enough protein for an athlete’s demanding training schedule?
Meat and animal-based products, including eggs, chicken, beef, and dairy, do provide a more concentrated, easily absorbable source of protein. However, plant-based protein sources, including beans, lentils, tofu, whole grains, nuts, and seeds, can still provide more than enough protein for athletes’ needs, while also being less inflammatory, supporting lower cortisol levels, and promoting resilience and recovery. And as long as you eat a variety of plant proteins throughout the day, you should easily be able to obtain a complete amino acid profile. Whether you choose to follow an exclusively plant-based diet or simply a more plant-forward diet, leaning on plant-based sources of protein can lead to greater health and performance outcomes.
So how do I know how much protein I need?
One can look at any nutrition label and get a pretty good estimate of how that particular food fits in with your daily calorie, carbohydrate, and fat intake needs. However, it is not so clear with protein. While the grams are listed, there is no indication of what percentage of our daily recommended intake that represents. Surprisingly, this is in part because the FDA knows that very few people in the US are protein deficient, and in fact most exceed what they actually need. Keep that in the back of your mind when you are worrying if you are getting enough protein. The fact is, you probably are, especially if your primary concern is just being healthy.
However, healthy does not necessarily equal optimal performance. If the latter is your goal, this is when we need to start considering some formulas. Stay with me, because I want to make this easy on you.
If you live in the US and are used to thinking of your own weight in pounds as opposed to kilograms, then the simplest way to accurately assess your protein needs is the following:
70% of your body weight in grams = your daily protein needs
Let’s say you weigh 150 lbs. Calculate 70% of that, which is 105. So you need about 105g of protein each day. Simple.
Lauren, you say, did you just make that formula up? Yes, I did. But I want to explain how I got there. For most people (i.e., the “general population”), 0.8g of protein per kg of body weight is sufficient to keep us healthy and serve all the muscle protein synthesis, immunity, hormone, and enzyme production needs we have. However, endurance athletes put a certain amount of stress on their bodies and muscles, resulting in a higher need, about 1.2 to 1.6 grams per kg of body weight. Ultra endurance athletes, with their extended training hours and miles, have a little extra work to do in getting adequate protein, with the general recommendation being 1.6 to 2 grams of protein per kg of body weight.
In a typical day of nutrition coaching with my own clients at Ultra Nutrition, I normally don’t recommend going much more than 1.6g (that number right in the middle), even for ultra endurance athletes. Why? Because your body has other needs besides protein. It needs carbohydrates for proper energy and protein sparing, healthy fats for heart, brain, and cellular health, vitamins and minerals for immunity, energy production, and recovery, and fiber for gut and metabolic health. Once you start stuffing yourself with excessive amounts of protein, it’s too easy to neglect the other important elements of your diet.
So what’s an easy way to remember this? If you do the math, 1.6 grams of protein per kilogram of body weight is the same thing as saying 70% of your body weight in grams.
As an ultra endurance athlete, that is plenty to support your training, as well as your health, recovery, performance, immunity, mood, and hormones, without sacrificing other important nutrients in your diet.
When should I get my protein?
Timing when you get your protein is almost as important as how much you get overall. While it might be easier to eat light before your workout, grab a quick recovery snack or protein drink afterward, eat something that seems healthy later in the day, and then stuff yourself with protein-rich foods for dinner, you’re really not doing your body any favors.
The fact is, your body loves consistency. It would much rather have its protein spaced evenly throughout the day. In fact, your body even has a sort of “minimum threshold” of roughly 20-30 grams of protein for initiating muscle protein synthesis. Getting about 25-30 grams of protein at four different meals throughout the day will keep your energy levels stable and more consistently promote that coveted muscle protein synthesis.
Keeping it in perspective
If you’re not a numbers person, never fear. Remember that most people are getting enough protein to be healthy. However, if you want to push the limits of what you are capable of as an athlete, you will need to support that with a little extra attention to your protein needs. Get it mostly from plants, get it throughout the day, and make sure you’re getting enough at each meal to keep your training and recovery strong. And if you really want to hone in on your nutrition as an athlete, get science-based, compassionate nutrition coaching with me at Ultra Nutrition to help you go from tired and injured to resilient and unstoppable.
Read more from Lauren Callahan
Lauren Callahan, Ultra Endurance Athlete Nutrition Coach
Ultra endurance athlete, nutrition coach, and doctoral student, Lauren Callahan is using science-based nutrition, compassionate coaching, and plant-forward strategies to transform endurance athletes from injured and tired to resilient and unstoppable. Passionate about gut health, plants, and pushing the edges of our limits, she guides endurance athletes to use nutrition to improve their health, mood, performance, hormones, and recovery.
