🔑 Key Takeaways
- New research shows athletes can benefit from higher protein intakes—up to 2–3 g/kg/day.
- The body can handle large protein feeds, but total daily intake remains the most critical factor.‍
- Plant-based athletes can match animal protein benefits with more variety and volume.‍
- Women, particularly during menopause, may require higher protein intakes due to anabolic resistance.
- This article is based on the conversation that Scott Tindal and Professor Stuart Phillips had on Fuelin Sessions. (you can listen to it HERE).
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Daily Protein Guidelines for Endurance Athletes: Making It Simple
In this article, we examine new findings in protein metabolism and translate them into practical guidance for endurance athletes. Whether you're plant-based, omnivorous, premenopausal, menopausal, or male, this is what you need to know about optimal protein intake.
🧠Rethinking Protein Dosing: The Case for Larger Feeds
One of the most talked-about recent studies in this space came out of Van Loon’s group and involved a straightforward question: What happens when you consume a significantly larger dose of protein in a single meal? The study involved six healthy, recreationally resistance-trained men between the ages of 18 and 40. Participants consumed either 0g, 25g, or 100g of a milk-based protein drink after a resistance training session. Using amino acid tracers, the researchers monitored muscle protein synthesis over 12 hours, substantially longer than the 4 to 6-hour windows seen in earlier studies.
The results were compelling. The group that consumed 100g of protein showed sustained MPS across the entire 12 hours, whereas the 25g group demonstrated a much shorter response. This suggests that larger single-protein feeds, when consumed after exercise, can deliver prolonged anabolic effects. Importantly, the study did not show that excess protein was simply oxidised or wasted; instead, the body appeared capable of absorbing and utilising a far greater protein load than previously thought.
However, it’s important not to overgeneralize. This was a small study, and the form of protein—a rapidly digested milk-based drink—likely influenced outcomes. Eating the equivalent in whole foods (say, 400g of chicken or beef) presents real-world challenges, including gastrointestinal comfort, nutrient displacement (e.g., reduced carbohydrate intake), and practicality around training schedules. While the findings open the door to flexible intake strategies, they don’t negate the value of spreading protein across the day for most athletes.
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🔢 The New Gold Standard: 2–3 g/kg Bodyweight
At Fuelin, our core recommendation—based on current evidence—is for athletes to target 2 to 3 grams of protein per kilogram of bodyweight per day.
This range supports:
- Enhanced recovery and muscle repair
- Better body composition
- Immune and connective tissue health
- Hormonal stability in female athletes
It is also especially relevant in periods of high training load, low energy availability, or for athletes navigating life stages such as menopause or aging. This intake level provides a solid buffer against the variability of day-to-day training stress and nutrition quality. It also reflects a growing body of research showing that the benefits of protein are dose-dependent to a much greater degree than previously appreciated. While a 1.6g/kg/day intake might suffice for sedentary individuals, it often falls short for highly active populations, especially endurance athletes training 10 to 20 hours per week or more. Ultimately, protein timing matters far less than previously thought. The primary goal is to meet daily protein needs consistently. If that means eating three larger protein-rich meals rather than five smaller ones, that’s perfectly acceptable, so long as the total intake is appropriate.
🌱 Plant vs Animal Protein: Quality and Quantity
Plant-based athletes often ask: can I build and maintain muscle on plants alone? The answer is yes—but it requires effort.
For plant-based athletes, hitting high daily protein targets requires both strategic planning and dietary diversity. Plant proteins tend to be lower in key amino acids like leucine and methionine, and their absorption rates can differ significantly from animal proteins. This does not mean plant proteins are inferior; instead, it highlights the importance of variety and volume. Consuming a range of plant-based sources—such as legumes, tofu, tempeh, seitan, whole grains, and pulses—can help athletes meet their essential amino acid needs. Combining complementary sources, like rice and beans or tofu and lentils, helps create a more complete amino acid profile. It’s also worth noting that some plant foods, such as soy, are exceptionally high in leucine and can effectively stimulate MPS on par with animal sources.
Some athletes may opt to fortify their plant-based diets with amino acid supplements like leucine or methionine. While effective in theory, these supplements often have an unpleasant taste and are less practical in real-world settings. Instead, we generally recommend a food-first approach wherever possible.
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đźšş Protein for Female Athletes: An Underfed, Undervalued and Understudied Population
Despite what social media suggests, protein needs for women—particularly around the menstrual cycle—remain understudied. What we do know is this:
1. The luteal phase may involve higher protein breakdown.
2. There’s no consistent difference in muscle protein synthesis (MPS) across the menstrual cycle.
3. Most female athletes don’t eat enough protein to support performance and adaptation.
Protein requirements for female athletes—particularly across different phases of the menstrual cycle and during menopause—are an under explored area in sports science & research. What little data we do have suggests that premenopausal women may experience greater protein breakdown during the luteal phase. However, studies examining muscle protein synthesis in this context have not shown significant differences between menstrual phases following resistance training, at least over a 24-hour window.
Despite the limited data, a clear trend emerges: many female athletes are under-consuming protein, especially when accounting for training load, energy availability, and hormonal fluctuations. At Fuelin, we advise premenopausal athletes to aim for at least 2-3 g/kg/day—toward the higher end of the general athlete range. This provides sufficient margin for the physiological variability inherent to female athletes and supports not just performance but also long-term health outcomes such as bone density and immune resilience.
🧓 Menopausal Athletes: Fighting Anabolic Resistance
Menopause brings with it a unique set of physiological changes, including reduced estrogen, impaired muscle protein synthesis, and increased protein breakdown—a phenomenon known as anabolic resistance. Even when menopausal athletes consume what would be considered adequate protein for younger athletes (1.6–2.0 g/kg/day), it may not be enough to maintain lean mass or prevent fat gain.
Recent research out of Australia has introduced the concept of the “protein leverage effect,” which suggests that inadequate protein intake drives overconsumption of fats and carbohydrates in an attempt to compensate. This, in turn, leads to increased total caloric intake, body fat accumulation, and further reductions in lean mass.
Our advice for menopausal athletes is clear: target the upper end of the range—2.0 to 3.0 g/kg/day. This higher protein intake can help offset the metabolic and hormonal changes of menopause, maintain lean body mass, and support continued athletic performance.
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đź•’ Timing and Distribution: Less Critical, Still Useful
Although older research emphasized tight "anabolic windows," newer studies show that total protein intake over 24 hours matters more than exact timing.
Still, spacing protein helps practically:
1. Avoids overloading the gut
2. Makes it easier to hit targets
3. Sustains amino acid availability throughout the day
If a large morning dose works for you, go for it. If multiple smaller meals suit your schedule better, that works too. Flexibility + consistency is the name of the game. Fuelin will provide the optimal framework based on your training schedule, and goals. If you want to adjust your intake on the day due to personal needs, that is absolutely fine to do.
Practical Application: Fuelin’s Protein Pyramid
At Fuelin, we’ve created a simple hierarchy to help athletes prioritise their protein strategy:
1. Total Daily Intake (Base)
Aim for 2–3 g/kg/day as a non-negotiable foundation. Men, Women, Young, Old
2. Protein Quality
Use high-quality sources or mix plant proteins to meet amino acid needs.
3. Timing and Distribution
Spread protein across the day based on schedule & practicality of intake; exact timing is flexible. Fuelin pulses protein based on your training timing, duration and intensity.
4. Adjust for Sex, Age, and Training Load
You can increase your intake towards upper limit if you are menopausal, plant-based, under high training stress, or recovering from injury. This will be your personal perference.
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🧾 CONCLUSION
Protein is essential for endurance athletes—not just to build muscle, but to recover, adapt, and stay healthy. And yet, many athletes (especially women and plant-based eaters) fail to meet optimal intakes. The evolving research shows that the body is capable of utilizing large protein feeds, but what matters most is total daily intake. Whether you’re training for Kona, Roth, or your next marathon, the advice is the same:
đź’¬ Eat enough, eat consistently, and choose diverse, high-quality protein sources. 2 to 3 grams per kilogram of bodyweight per day is your anchor.
We are witnessing a paradigm shift in how we think about protein intake for endurance athletes. The old models—focused on minimal doses and narrow anabolic windows—are giving way to more flexible, evidence-based strategies that emphasise total daily intake, protein quality, and individualised needs. Whether you’re a plant-based athlete, a premenopausal woman, or a 60-year-old masters competitor, the core recommendation holds: eat enough protein, consistently, and from a variety of sources.
Our updated stance at Fuelin is clear. For optimal performance, recovery, and long-term health, endurance athletes should aim for 2 to 3 grams of protein per kilogram of body weight per day. This foundation allows room for practical flexibility while supporting the physiological demands of high-level training. The future of endurance fueling is not just about carbs.
Thanks for reading,
Scott
đź“© Questions?
If you’re an endurance athlete unsure how to personalize your protein strategy, drop us a message or speak to a Fuelin coach. We’re here to help you fuel smarter, train harder, and recover faster.
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