Most cyclists know the number by now. It is one of the most frequently quoted figures in cycling nutrition. You need 1.6 to 2.2 grams of protein per kilogram of bodyweight per day. If you weigh 75 kilograms, that is somewhere between 120 and 165 grams daily. I have covered the evidence behind those numbers, the distribution across meals, and the leucine threshold in the complete protein guide. That post is the "how much and when."
This one is the "what."
Because here is the thing nobody tells you: two meals can deliver 35 grams of protein each and produce completely different recovery outcomes. A chicken breast and a bowl of rice with beans both register similar protein numbers. But the amino acid profiles differ, the leucine content differs, the digestibility differs, and the practical reality of preparing them differs. If you are going to eat 160 grams of protein a day for the next year, you had better know what to fill those grams with — otherwise you are doing the hard work of tracking and measuring without getting the full return.
This is a practical shopping guide for your muscles.
Complete versus incomplete proteins
Before ranking specific foods, you need to understand what makes one protein source fundamentally different from another. The answer sits at the amino acid level.
Proteins are chains of amino acids. There are twenty of them in total, and your body uses all twenty to build and repair muscle tissue. Eleven of those twenty can be manufactured internally — your liver synthesises them from other compounds. These are the non-essential amino acids. Not because they are unimportant, but because you do not need to eat them.
The remaining nine cannot be made internally. They must come from food. These are the essential amino acids: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Miss any one of them and the repair process stalls at whatever point that amino acid was needed. Think of it like building a wall — if you have every brick except the corner pieces, the wall does not get 90 per cent built. It stops at the first missing corner.
A complete protein contains all nine essential amino acids in sufficient quantities to support muscle protein synthesis. An incomplete protein is low in one or more.
Here is where it gets really interesting. Every animal-based protein source — eggs, dairy, fish, poultry, red meat — is complete. They contain all nine essential amino acids in roughly the proportions your muscles need. This is not surprising. Animal muscle tissue is structurally similar to human muscle tissue, so the building blocks match up.
Plant-based proteins are mostly incomplete. Legumes (lentils, chickpeas, black beans) are low in methionine. Grains (rice, wheat, oats) are low in lysine. Nuts and seeds vary, but most are low in lysine or threonine. There are two notable exceptions: soy and quinoa. Both deliver a complete amino acid profile from a single source. Everything else requires deliberate combining.
The good news: you do not need to combine complementary proteins in the same meal. The old advice — rice and beans together, peanut butter on wholemeal bread — was well-intentioned but unnecessarily rigid. Research from the American Dietetic Association confirms that consuming complementary amino acids across a full day maintains adequate amino acid availability. Eat lentils at lunch and rice at dinner and your body pools the amino acids across both meals.
But there is a caveat. If you are eating three or four meals a day and each meal needs to hit the leucine threshold independently to trigger muscle protein synthesis, then the amino acid profile of each individual meal still matters. You cannot bank leucine from breakfast and spend it at dinner. That is where source selection becomes critically important — and where the leucine rankings come in.
Protein sources ranked by leucine content
Leucine is the master switch. It activates the mTOR signalling pathway, which initiates muscle protein synthesis. Without enough leucine in a single dose — roughly 2.5 to 3 grams — the switch does not fully turn on. You need to hit that threshold at every meal, not just across the day.
Different protein sources deliver wildly different amounts of leucine per gram of protein. This table ranks the most common options by leucine density — the percentage of the protein that is leucine — so you can see at a glance how much of each food you actually need.
| Source | Serving | Protein (g) | Leucine (g) | Leucine density | Hits 3g threshold? | |---|---|---|---|---|---| | Whey protein isolate | 30g scoop | 25-27 | 2.8-3.0 | ~11% | Yes | | Casein protein | 30g scoop | 24-26 | 2.3-2.5 | ~9.5% | Borderline | | Eggs (3 large) | 180g | 18-19 | 1.6-1.8 | ~9% | No — needs pairing | | Chicken breast | 150g | 46 | 3.5 | ~7.5% | Yes | | Turkey breast | 150g | 44 | 3.3 | ~7.5% | Yes | | Salmon fillet | 150g | 34 | 2.6 | ~7.5% | Borderline | | Lean beef mince | 150g | 38 | 3.0 | ~8% | Yes | | Greek yoghurt | 200g | 15-20 | 1.8-2.2 | ~9% | No — needs pairing | | Cottage cheese | 250g | 28 | 2.5 | ~9% | Borderline | | Skyr | 200g | 22 | 2.0 | ~9% | No — needs pairing | | Tinned tuna | 130g | 30 | 2.4 | ~8% | Borderline | | Soy protein isolate | 30g scoop | 25 | 2.0 | ~8% | No | | Tofu (firm) | 200g | 20 | 1.5 | ~7.5% | No | | Tempeh | 200g | 38 | 2.6 | ~7% | Borderline | | Lentils (cooked) | 200g | 18 | 1.3 | ~7% | No | | Chickpeas (cooked) | 200g | 15 | 1.0 | ~7% | No | | Quinoa (cooked) | 200g | 9 | 0.6 | ~6.5% | No | | Pea protein isolate | 30g scoop | 22 | 1.8 | ~8% | No | | Rice protein isolate | 30g scoop | 24 | 1.9 | ~8% | No |
Let me break this down.
The top tier: whey, chicken, turkey, lean beef
Whey protein isolate sits alone at the top for leucine density. At 11 per cent leucine by weight, a single 27-gram scoop clears the 3-gram threshold. Nothing else is that efficient. Chicken and turkey breast clear it comfortably at standard serving sizes — 150 grams is a normal portion, and you are well above 3 grams of leucine. Lean beef mince at the same serving hits the threshold precisely.
These four sources are the most reliable triggers for muscle protein synthesis per meal. If you ate nothing else, these would cover you.
The practical middle: eggs, Greek yoghurt, cottage cheese, salmon
These are the sources that earn their place through versatility rather than raw leucine numbers.
Eggs are the single most nutrient-dense protein source per calorie available to cyclists. Two large eggs deliver 12 grams of protein, 1.2 grams of leucine, plus choline (essential for cell membrane integrity and nervous system function), vitamin D (which most people in northern latitudes are deficient in), and vitamin B12 (critical for red blood cell production — directly relevant to your oxygen-carrying capacity). They cost next to nothing. They take four minutes to scramble. They work at breakfast, lunch, dinner, or as a snack. If you are only going to focus on one protein source, make it eggs.
The leucine limitation is real, though. Three eggs deliver about 1.7 grams — short of the threshold. The fix is simple: pair eggs with another source. Two eggs plus 100 grams of Greek yoghurt clears 2.5 grams. Three eggs plus a small whey shake clears 3 grams easily. Eggs are the foundation, not the entire structure.
Greek yoghurt occupies a really useful middle ground. It delivers 15 to 20 grams of protein per 200-gram serving with both whey and casein fractions — meaning you get a fast MPS trigger from the whey component plus sustained amino acid delivery from the casein. It works as a post-ride recovery food (fast fraction), a pre-sleep protein dose (slow fraction), or a meal component. The leucine is borderline at a standard serving, so pairing with a handful of nuts, some seeds, or a partial whey scoop closes the gap.
Salmon brings something the others do not: omega-3 fatty acids. EPA and DHA have anti-inflammatory properties that are directly relevant to recovery from endurance exercise. Professor Philip Calder at the University of Southampton has published extensively on this — omega-3 supplementation reduces exercise-induced muscle damage markers and may accelerate recovery. Getting your protein and your omega-3s in the same meal is efficient. Two to three salmon meals per week covers both bases.
Cottage cheese is the unsung workhorse. It is predominantly casein, making it the best whole food option before bed. A 250-gram serving delivers 28 grams of protein that digests slowly across the overnight period. It is bland enough to eat plain, cheap enough to buy in bulk, and requires zero preparation. Not glamorous. Effective.
The plant tier: soy, tempeh, tofu, legumes, grains
None of these individually clear the leucine threshold at standard servings. That is not a disqualification — it is a design constraint that requires a different approach.
Soy protein isolate is the strongest single plant source. Its amino acid profile is complete, its leucine content sits at roughly 8 per cent, and its DIAAS (Digestible Indispensable Amino Acid Score) is the highest of any plant protein. If you are plant-based and want a supplement, soy isolate is the foundation.
Tempeh is the whole food standout. At 200 grams, it delivers 38 grams of protein with 2.6 grams of leucine — borderline threshold territory. It is fermented, which improves digestibility and nutrient absorption. It also delivers iron, calcium, and probiotics. It is denser calorically than chicken or fish, so portion management matters if you are watching total energy intake, but as a protein source it is seriously impressive.
Tofu is versatile but leucine-poor. Firm tofu at 200 grams delivers 20 grams of protein but only 1.5 grams of leucine. You need a significant volume — 400 grams — to approach the threshold from tofu alone, which is impractical in a single meal. Better to use 200 grams of tofu and supplement with a pea-rice protein blend to close the leucine gap.
Lentils, chickpeas, and beans deliver 15 to 18 grams of protein per 200 grams cooked, but their leucine content is low and they are missing methionine. They work as meal components, not meal centres. Pair them with grains (which supply methionine) and add a leucine-rich source — some seeds, a drizzle of tahini, or a soy-based component — and the meal gets much closer to complete.
Quinoa is technically complete but protein-sparse. At 9 grams per 200 grams cooked, you would need an absurd volume to hit 30 grams in a sitting. Use it as a carbohydrate base that contributes a few extra grams and a full amino acid spectrum, not as a primary protein source.
Plant-based cycling nutrition: making it work
I have spoken to enough plant-based athletes on the podcast — and worked with enough in the community — to know this is entirely viable. But it is harder. Not impossibly harder. Meaningfully harder. The margin for error is smaller, and the consequences of lazy planning are bigger.
Here are the three adjustments that make plant-based protein work for endurance cycling.
Increase total intake by 10 to 20 per cent. Plant proteins have lower digestibility scores than animal proteins. The DIAAS for soy isolate is around 0.90. For pea protein, 0.82. For lentils, 0.65. Compare that to whey at 1.09 or eggs at 1.13. Lower digestibility means less of the protein you eat is actually absorbed and available for synthesis. Bumping your target from 1.8g/kg to 2.0 to 2.2g/kg compensates for this gap.
Combine deliberately. Every meal should include at least two complementary protein sources. The classic pairings: legumes plus grains (lentils and rice, chickpeas and couscous, black beans and corn tortillas). Legumes plus seeds (hummus with pumpkin seeds, edamame with sesame). Soy with anything (tofu stir-fry with brown rice, tempeh with quinoa). These combinations cover each source's amino acid weakness.
Consider supplementing leucine directly. If your food choices are consistently falling short of the 2.5-gram leucine threshold, adding 1 to 2 grams of free-form leucine powder to a meal is a practical and inexpensive strategy. It costs pennies per serving and converts a sub-threshold plant meal into one that fully triggers MPS. Professor Luc van Loon's research group at Maastricht University has studied this approach specifically and found that leucine-fortified plant protein meals produce MPS responses comparable to animal protein meals.
Training days versus rest days: practical meal structures
Your total daily protein does not change between training days and rest days. Whether you rode for four hours or sat on the sofa, your muscles need the same raw material. What changes is the distribution pattern and the carbohydrate alongside it.
Training day structure (75kg rider, target 150g protein)
Pre-ride (2 hours before): 3 eggs scrambled on sourdough toast with a side of Greek yoghurt. Roughly 25g of protein, 1.8g leucine. This is a moderate dose — enough to have amino acids circulating without sitting heavy in the gut.
Post-ride (within 2 hours): Whey isolate shake with a banana, or a chicken breast wrap if appetite allows solid food. Target 30-40g of protein here. This is where leucine density matters most — whey gets amino acids into the blood fastest, and the leucine hit triggers MPS while the repair window is at its widest.
Dinner: 150g salmon fillet with roasted vegetables and sweet potato. 34g of protein, 2.6g leucine, plus omega-3s. The carbohydrate from the sweet potato supports glycogen replenishment alongside the protein repair.
Pre-sleep: 250g cottage cheese with a sprinkle of cinnamon. 28g of casein-dominant protein that will sustain amino acid delivery across the overnight period. If cottage cheese is not your thing, 200g of Greek yoghurt with a scoop of casein powder achieves the same effect.
Daily total: approximately 120-130g protein across four feeds, with the remainder coming from incidental protein in carbohydrate sources (oats, bread, rice all contribute small amounts). Adjust portions up if your target is higher.
Rest day structure (75kg rider, target 150g protein)
Breakfast: Greek yoghurt bowl — 200g Greek yoghurt, 30g whey mixed in, berries, handful of mixed seeds. 35g protein, well above the leucine threshold. Rest days allow a higher-protein breakfast because there is no concern about gut comfort during a ride.
Lunch: Tinned tuna salad with mixed leaves, chickpeas, olive oil, and sourdough. 35g protein from the tuna and chickpeas combined. This is also where plant-based eaters can load a larger combination meal — lentil soup with a soy-based side, tempeh and rice bowl, tofu stir-fry with edamame.
Afternoon snack: 3 boiled eggs with hummus and vegetable sticks. 20g protein. A bridging dose that keeps the MPS signal ticking between lunch and dinner.
Dinner: Lean beef mince bolognese with wholemeal pasta. 38g protein from the mince alone, plus incidental protein from the pasta. Replace the mince with tempeh or lentil-based mince for a plant-based version — just add a leucine top-up.
Pre-sleep: Cottage cheese or casein shake. 28-30g protein.
Daily total: approximately 155-160g across five feeds. The distribution is more even than on training days because there is no single high-priority post-ride window pulling the timing forward.
The key difference between the two days is not protein quantity — it is carbohydrate quantity. Training days demand high carbohydrate to fuel and replenish. Rest days drop carbohydrate because glycogen stores do not need topping up. Protein stays constant because muscle protein synthesis from the previous day's session is still elevated for 24 to 48 hours. Cutting protein on rest days because you "did not train" is one of the most common mistakes in endurance nutrition.
Supplements versus whole food: the honest assessment
The supplement industry would have you believe that without their products, you are leaving performance on the table. The whole food purists would have you believe that supplements are unnecessary processed nonsense. Neither position is accurate.
Here is what the evidence actually says.
Whole food advantages. Real food delivers more than protein. A chicken breast comes with B vitamins. Salmon comes with omega-3s. Eggs come with choline and vitamin D. Lentils come with fibre and iron. Greek yoghurt comes with probiotics and calcium. These micronutrients and bioactive compounds contribute to overall health and recovery in ways that isolated protein powder cannot replicate. A 2021 systematic review by Burd et al. in the Journal of Nutrition concluded that whole food protein sources produced superior anabolic responses compared to isolated protein in several — though not all — contexts, likely due to the "food matrix" effect where nutrients interact synergistically during digestion.
Supplement advantages. Whey protein isolate is the most leucine-dense protein source available. It absorbs faster than any whole food. It requires no preparation, no refrigeration (in powder form), and no chewing. After a four-hour ride in July when the thought of eating chicken makes you gag, a cold whey shake in water takes 30 seconds and gets amino acids into your bloodstream within the hour. That is not a trivial advantage. It is the difference between hitting your post-ride protein target and skipping it because you could not face food.
The practical position. Build your protein intake around whole food. Eggs, Greek yoghurt, chicken, fish, legumes, cottage cheese — these should form the backbone. Use whey protein isolate in three specific situations: immediately post-ride when appetite is suppressed, when travelling and whole food options are limited, and when a meal falls short of the 30-gram target and you need a convenient top-up. That approach gets you the micronutrient benefits of real food and the practical benefits of supplementation, without relying on either exclusively.
Casein protein — either as a dedicated supplement or in the form of cottage cheese and Greek yoghurt — has a specific use case before sleep. The slow-digesting properties are particularly useful during the overnight fasting period, and the evidence from Snijders et al. supports the practice. This is one area where the supplement science is solid and the application is straightforward.
What I would avoid: mass gainers (unnecessary calories, poor protein quality), BCAAs (redundant if you are hitting your protein targets — leucine is already in the food), and protein bars as a staple. Protein bars are fine occasionally, but most are engineered for taste rather than amino acid quality. Check the leucine content — many bars deliver 20 grams of protein but only 1.5 grams of leucine because the protein source is collagen or gelatin blended with cheaper fractions. That is not the same as 20 grams from whey or egg.
Six mistakes that cost you recovery
After 1,400 episodes of conversations with sports nutritionists and exercise physiologists, these are the protein source mistakes I see most often in endurance cyclists.
Counting grams without checking leucine. You can eat 30 grams of protein from collagen powder and trigger almost zero muscle protein synthesis, because collagen is virtually devoid of leucine. The gram count on the label is only half the story. Leucine content per serving is the other half. If your protein source does not tell you the leucine content, it probably does not want you to know.
Relying on protein bars as a primary source. Most protein bars use a blend of whey concentrate, milk protein, soy crisps, and sometimes collagen or gelatin to hit their label claim. The amino acid profile of the finished product is often mediocre. A bar that says 20 grams of protein might deliver the leucine equivalent of 12 grams from a high-quality source. Bars are fine as an occasional convenience. They are not a substitute for actual food.
Skipping protein on rest days. Muscle protein synthesis from a hard training session remains elevated for 24 to 48 hours. Your rest day is when a significant portion of the repair actually happens. Dropping protein because you "did not earn it" undercuts the adaptation from the session you already did. Carbohydrate can drop. Protein stays.
Eating all your protein at dinner. The classic pattern — cereal for breakfast, a sandwich for lunch, and a large meat-based dinner — concentrates 60 to 70 per cent of your daily protein in one meal. Your body uses 30 to 40 grams for synthesis and oxidises the rest. Those grams are wasted. Redistributing 20 to 30 grams from dinner to breakfast produces measurably more muscle protein synthesis over a 24-hour period, even when total intake is identical.
Ignoring pre-sleep protein. The overnight period is seven to nine hours of fasting. Without a pre-sleep protein dose, muscle protein breakdown exceeds synthesis for most of that window. A 250-gram serving of cottage cheese or a casein shake before bed costs almost nothing in terms of effort and fundamentally shifts the overnight balance towards repair. This is one of those small little leaks that drains recovery over weeks and months without you noticing.
Assuming all plant proteins are interchangeable. Lentils, chickpeas, tofu, tempeh, soy isolate, pea protein, rice protein, and quinoa all have different amino acid profiles, different leucine contents, and different digestibility scores. Treating them as a single category leads to gaps. Tempeh at 200 grams delivers nearly double the leucine of chickpeas at the same weight. Soy isolate has a DIAAS three times higher than wheat protein. If you are plant-based, knowing the hierarchy within plant sources is not optional — it is the difference between adequate and suboptimal recovery.
Putting it together
Protein source selection is not complicated once you understand the framework. Every meal needs to clear the leucine threshold. Complete proteins do that more efficiently than incomplete ones. Animal sources are inherently complete; plant sources require combining. Whole food delivers micronutrients that supplements cannot; supplements deliver convenience that whole food cannot.
Build your weekly rotation around eggs, Greek yoghurt, chicken or turkey, fish (especially salmon twice a week for the omega-3s), and cottage cheese before bed. If you are plant-based, build around tempeh, tofu paired with grains, soy isolate, and deliberate legume-grain combinations — and consider supplementing leucine directly at meals that fall short. Use whey protein when convenience demands it. Avoid collagen-based products, low-quality bars, and anything marketed with promises that outstrip its amino acid profile.
The numbers matter. The timing matters. But the source is where the rubber meets the road — or, more accurately, where the amino acids meet the muscle.
If you want to talk through your specific protein strategy — what to eat around your training schedule, how to structure rest day nutrition, or how to make plant-based work for serious endurance training — the Roadman Cycling community on Skool is where those conversations happen daily. Riders sharing meal prep, comparing what works, and holding each other accountable to actually eating enough. Come join us.