Week 9, Thursday. 14 miles done, legs like concrete. Ate a massive bowl of pasta after — felt virtuous. Friday’s easy 6 felt like wading through mud. Saturday: looked back at the week and realised I’d eaten maybe 70g of protein a day. Seventy. While running 55 miles.
In this article
That log entry is from my first marathon block, and it captures the great blind spot of distance running: runners obsess over carbs — gels, pasta parties, “carb-loading” — while protein quietly starves. How much protein do runners need? 1.4–1.8g per kilogram per day, rising with mileage. Most club runners I know eat half that, then wonder why niggles never heal and the last six miles of the marathon feel like a death march.
Why Running Is Secretly Protein-Hungry
Every footstrike is a small collision — roughly two to three times your body weight, thousands of times per run. That impact damages muscle fibres, and the damage scales with distance. A 5k jog barely registers; a 20-mile long run is a demolition job that your body then has to repair. Repair needs amino acids, and lots of them.
Then there’s the fuel problem. Past about 90 minutes, glycogen runs low and the body starts burning a meaningful amount of protein for energy — up to 5–10% of calories on very long runs. That’s protein being used as fuel instead of repair material, which raises the intake needed to cover both jobs. Add the immune suppression that follows hard endurance efforts (marathoners catch colds for a reason), and protein’s role in immune function becomes relevant too.
Runners also carry less muscle than lifters, which creates a cruel irony: they have less tissue to spare and often eat less protein to protect it. The British Dietetic Association flags elevated needs for endurance athletes — this isn’t a bodybuilding opinion, it’s mainstream sports nutrition.
Protein by Mileage
| Your running | Protein range | At 70kg | Notes |
|---|---|---|---|
| Under 30 km/week, easy running | 1.2–1.4 g/kg | 84–98g | Above the NHS baseline, nothing dramatic |
| 30–60 km/week, club training | 1.4–1.6 g/kg | 98–112g | Where most committed runners live |
| 60+ km/week, marathon block | 1.6–1.8 g/kg | 112–126g | Long runs demand serious repair material |
| Ultra / back-to-back long runs | 1.8–2.0 g/kg | 126–140g | Damage and fuel use both peak |
During my marathon block I was running 85–90km weeks — firmly in the 1.6–1.8 bracket — while eating like a 30km/week jogger. The maths of my fatigue was obvious in retrospect. Within three weeks of fixing protein (not changing a single run), the heavy-legs feeling lifted noticeably. Food was the missing training variable.
The Runner’s Formula
One-point-six covers the large middle of runners — regular club training, the odd race, a long run most weekends. At 68kg that’s 109g; at 80kg, 128g. Marathon-block runners should use 1.7–1.8; casual 5k runners can use 1.2–1.4 and stop reading.
Timing gets a special note for runners because of the post-long-run window. After 90+ minutes, muscle damage is high and glycogen is low — a meal with 30–40g of protein plus plenty of carbs within a couple of hours genuinely aids recovery. This isn’t the discredited “anabolic window” panic; it’s just sensible refuelling when the tank is empty. Chocolate milk, incidentally, is a legit recovery drink — ~20g protein per 500ml plus fast carbs — and about a pound from any supermarket.
Recovery Meals That Hit the Numbers
| When | Meal | Protein |
|---|---|---|
| Post-long-run | Big bowl: 100g oats, 500ml milk, banana, honey, 30g whey | ~45g |
| Normal training day lunch | Chicken and rice meal-prep box, 150g chicken | ~40g |
| Race-week dinner | Salmon fillet, large potato wedges, veg | ~35g |
| Easy-day breakfast | 3-egg omelette on toast | ~25g |
| On-the-go | 500ml chocolate milk + banana | ~22g |
Notice carbs are high alongside the protein — that’s deliberate. Runners fear carbs the way lifters fear fat, and both fears are misplaced. Protein repairs; carbs refuel. A marathoner’s plate should be built around both, not one at the expense of the other. The British Nutrition Foundation has good material on fuelling endurance sport if you want the carb side of the equation too.
Getting Your Figure
The Protein Intake Calculator on the home page handles runners fine — enter your weight, pick your goal (most runners want “maintain” with high activity, or “lose weight” in a careful off-season cut), and it returns the target with a per-meal split. For the daily mechanics of hitting it, the protein tracking guide covers the simplest system I’ve found. One week of tracking usually reveals the gap — most runners are shocked.
Race Week and the Long Run: Protein in Context
Protein doesn’t operate in isolation on race week — it shares the stage with carb-loading, hydration and nerves. Here’s how to handle the final seven days without overthinking:
Keep protein steady while carbs rise. The classic mistake is carb-loading by replacing protein — three days of pure pasta with no chicken in sight. Don’t. Keep your normal 1.6g/kg protein (your muscles still need maintenance during taper), and add the extra carbs on top. A marathoner’s carb-load plate should look like your normal dinner with double rice, not a different dinner entirely.
The night before: normal, not experimental. Eat the pre-long-run dinner you know — for me it’s salmon, rice and veg, ~35g protein, eaten at 6pm. Race eve is the worst possible time for a new cuisine, an enormous steak, or anything your gut hasn’t rehearsed. Boring wins medals.
Race morning: small, familiar, 15–20g protein max. Porridge with milk and honey, or toast with peanut butter and a banana — eaten 2–3 hours before the start. This isn’t the meal for a 40g protein bomb; heavy protein sits in the stomach, and race morning is about topping up glycogen, not maximising amino acids. Save the big protein for the finish line.
After the finish: the 2-hour refuel. Within a couple of hours, get 30–40g of protein with plenty of carbs — the classic post-marathon burger and chips is actually decent recovery science (protein + carbs + salt + joy). Then eat normally for the next 48 hours at the top of your range (1.8g/kg); muscle damage from a marathon takes days to repair, and under-eating the week after the race is how niggles become injuries.
One thing I learned the hard way: don’t diet through marathon training. I tried to lose 3kg during that first block — performance tanked, recovery doubled, and I caught two colds. Fuel the training, race the weight later. The runners who try to do both usually fail at both.
Hydration: Protein’s Forgotten Partner
High protein plus low water is a recipe for feeling terrible — headaches, constipation, that thick sluggish feeling on long runs. Protein metabolism produces urea, which your kidneys flush with water; more protein means more water needed for the job. The standard runner’s rule of thumb: pale-yellow urine, drinking to thirst plus a bit extra on high-protein days.
In practical terms, add roughly 500ml of water for every 50g of protein above your old baseline — so jumping from 70g to 130g means an extra pint or so through the day. On long-run days the maths compounds: you’re losing litres to sweat and processing more protein, so the post-run refuel should be food plus serious rehydration, not just food. My marathon-block fatigue improved twice: once when I fixed protein, and again two weeks later when I realised I was chronically half a litre short on water and fixed that too.
Electrolytes matter on the long stuff — water alone for 3+ hour runs dilutes blood sodium. A pinch of salt in your post-run meal, or an electrolyte tab in the bottle, covers it. Boring, cheap, effective — the holy trinity of things runners ignore while buying £180 shoes.
Runner Protein Questions
How much protein do runners need compared to lifters?
Surprisingly similar: 1.4–1.8g/kg for runners vs 1.6–2.2g/kg for lifters. The old idea that endurance athletes need far less protein is outdated — impact damage and fuel use close the gap more than people expect.
Will extra protein make me gain weight and slow down?
Only if it pushes you into a calorie surplus. Protein itself doesn’t slow anyone down; carrying excess body fat slows runners, and adequate protein during training actually helps keep body composition lean.
Do I need protein during a long run?
For runs under 2 hours, no — carbs and water suffice. For ultras (3+ hours), some protein in your fuelling (a few grams per hour from real food or drink mixes) may reduce muscle damage. It’s a marginal gain, not a necessity.
What about protein and running injuries?
Chronic under-fuelling — low protein and low overall calories — is implicated in stress fractures and slow-healing niggles via the RED-S (relative energy deficiency) mechanism. If you’re injured and under-eating, that’s the first thing to fix, before the physio exercises.
Is plant-based protein OK for runners?
Yes, with attention to quantity — plant proteins digest slightly less efficiently, so aim for the top of your range (1.6–1.8g/kg) and vary sources. Plenty of elite distance runners are plant-based; the planning just needs to be deliberate.
