How do I convert the 1.6 g/kg formula if I weigh 175 lb?

Divide your weight in pounds by 2.2 to get kilograms (175 ÷ 2.2 ≈ 79 kg) and multiply by 1.6. Your target is about 126 g protein per day.

Should I eat even more protein on long-run days?

Yes—add roughly 0.3 g/kg (about 20 g for most runners) within 30 minutes after runs longer than 90 minutes.

Is plant-based protein enough for marathon training at 45?

Absolutely, but you may need 10 % more total protein and must combine legumes, soy, and grains to reach all essential amino acids.

Can high protein damage my kidneys?

People with normal kidney function generally tolerate up to 2 g/kg without harm; check eGFR yearly if you plan to stay at the high end.

Do BCAAs help endurance runners?

Whole-protein foods outperform isolated BCAAs, but a 5-g BCAA sip may curb mental fatigue late in ultra-long runs.

What if I’m also trying to lose 10 lb?

Maintain protein at 1.8–2.0 g/kg to preserve muscle while trimming carbs or fats; this approach cuts injury risk during calorie deficit.

Is collagen useful for tendon health while upping mileage?

Taking 15 g collagen with vitamin C an hour before plyometrics shows modest benefit in small studies, but it doesn’t replace core protein needs.

How soon before a race should I adjust protein intake?

Keep your established intake through taper; reducing protein can impair immune function right before race day.

I’m 45 and Training for a Marathon—Exactly How Much Protein Do I Need Each Day?

What is the daily protein target for a 45-year-old marathon trainee?

Endurance athletes need more protein than sedentary adults, and age adds another bump because muscle becomes less responsive to protein (so-called anabolic resistance). For most healthy runners at 45, 1.6 g/kg/day is the sweet spot.

1.6 g/kg/day meets most needsResearch in Masters endurance athletes shows muscle protein synthesis plateaus near 1.6 g/kg/day; that’s 109 g for a 150-lb runner.
Higher mileage may push toward 1.8 g/kgDuring 60-mile training weeks, breakdown rises; a 150-lb runner would then aim for ~122 g.
Distribute protein across the dayFour meals of 25–30 g each outperform a single large dose for muscle repair.
Prioritize leucine-rich sources2–3 g leucine per meal (e.g., 3 oz chicken or 1 scoop whey) maximizes muscle signalling.
ISSN sets 1.4–1.8 g/kg as the evidence-based zoneThe International Society of Sports Nutrition recommends endurance athletes consume 1.4–1.8 g of protein per kg body weight daily to aid recovery, lean-mass maintenance and injury prevention during marathon prep. (WMM)
Older runners benefit from ~40 g protein dosesGuidelines for masters endurance athletes suggest aiming for about 40 g protein at each meal to counteract anabolic resistance and maximize muscle-building signals. (NB)

When is low protein hurting your marathon training?

Persistent soreness, slow recovery, or repeated colds can signal that protein intake is insufficient. As Sina Hartung, MMSC-BMI, says, “If you’re dragging 48 hours after every long run, think protein before blaming age.”

Soreness lasting beyond 48 hoursDelayed-onset muscle soreness that lingers more than two days often improves when protein exceeds 1.5 g/kg.
Unexplained plateau in paceLow protein can reduce mitochondrial enzymes, cutting running economy by up to 5 % in studies.
Frequent upper-respiratory infectionsImmunoglobulin A drops 20 % in athletes eating <1.2 g/kg, increasing infection risk.
Mid-season weight loss >3 %Losing more than 3 % body weight unintentionally often means you’re catabolizing muscle.
Masters runners may need up to 2.4 g/kg of protein dailyA study of marathoners over 40 linked intakes as high as 2.4 g/kg with better finish times and preservation of lean mass compared with those near the 0.8 g/kg RDA. (RW)
Research pins average endurance requirement at 1.65 g/kg/dayMetabolic tracer data showed distance runners needed about 1.65 g/kg of protein (with 1.8 g/kg recommended) to stay in positive nitrogen balance—roughly double what non-athletes require. (RW)

Why do runners over 40 often miss their protein goal even when they ‘eat well’?

Busy schedules and outdated nutrition myths keep many Masters runners under-fuelled. The team at Eureka Health notes, “Most patients overestimate protein in plant dishes by two-fold.”

Relying on carb-heavy recovery snacksA plain bagel offers only 11 g protein but 55 g carbs—fine for glycogen, not for muscle.
Skipping breakfast on workdaysMissing one meal cuts daily protein by 25–30 %, leaving no room to catch up later.
Counting beans as high-proteinOne cup black beans supplies 15 g protein but 40 g carbs; you’d need 7 cups for 105 g.
Evening appetite drop post-runLong runs suppress ghrelin; athletes consume 200–400 fewer kcal and miss protein windows.
Older muscles need 35–40 g protein after hard workoutsExperts quoted by Runner’s World advise masters runners to consume 35–40 g of high-quality protein within the recovery window; a typical protein bar delivers only 20–25 g, so many athletes fall short. (RW)
Protein requirements may climb to 1.6–2.4 g/kg in masters athletesResearch highlighted by Runner’s World showed marathoners who hit 1.6–2.4 g protein per kg body weight preserved lean mass and raced faster—levels most ‘clean eaters’ never reach. (RW)

How can I hit my protein goal without digestive distress?

Large single servings can feel heavy, especially before runs. Sina Hartung suggests, “Think protein mini-meals—your gut and muscles both win.”

Use 20–25 g whey or soy isolate in smoothiesIsolates are >90 % protein and low lactose, reducing bloating for 80 % of sensitive runners.
Opt for Greek yogurt with berries as a night snack200 g yogurt delivers 17 g casein, providing slow amino acid release during sleep.
Include eggs or tofu at breakfastTwo eggs plus ½ cup tofu offers 26 g protein in under 300 kcal.
Portable options for workdaysSingle-serve tuna packs (18 g) or roasted edamame (14 g) fit in a desk drawer.
Post-long run chocolate milk upgradeChoose high-protein (13 g) versions to match the 3:1 carb-to-protein recovery ratio.
Spread protein through the day in 20–30 g meals and 15–20 g snacksISSN guidance for endurance athletes advises dividing intake into moderate portions, which lightens the load on your stomach while maximizing muscle repair. (TRM)
Start with 1.2–1.4 g protein per kg body weight dailyMarathon plans set this range as a workable target—about 82–95 g for a 150-lb runner—making it feasible to meet goals without oversized servings. (MarathonPal)

Which lab tests and supplements matter for protein metabolism after 45?

Monitoring kidney function and vitamin D helps ensure higher protein is safe and useful.

Annual eGFR and creatinineMost healthy runners tolerate up to 2 g/kg protein, but baseline eGFR should be >60 mL/min.
Serum 25-OH vitamin DLevels below 30 ng/mL blunt muscle protein synthesis; 42 % of Masters athletes are low.
Ferritin check for endurance fatigueFerritin under 30 ng/mL can mimic low protein fatigue; treat iron before boosting protein further.
Leucine or HMB supplements2–3 g leucine or 3 g HMB post-workout may reduce muscle breakdown by 20 %, but confirm need with a professional.
Distribute protein in 20–25 g servings every 3–4 hCoach Jim Rutberg recommends older endurance athletes target about 0.3 g/kg (roughly 20–25 g) of protein per meal throughout the day to maximize muscle-protein synthesis and limit age-related breakdown. (CTS)
Higher daily protein protects lean mass in master marathonersIn 58 runners averaging 58 years old, those who consumed the most protein before race day showed smaller post-race declines in lean body mass and fewer adverse blood-marker changes, underscoring the value of ≥1.5 g/kg when training hard after 45. (Elsevier)

Can Eureka’s AI doctor calculate a personalized protein plan for my marathon build?

Yes. Upload your weight, weekly mileage, and recent labs, and Eureka’s AI sets a gram-by-gram target, factoring in kidney function and injury history.

Dynamic adjustment as mileage climbsThe plan automatically bumps protein 0.1 g/kg for every 10 % increase in long-run distance.
Evidence-based food suggestionsEureka lists food portions—e.g., “Add 3 oz salmon at lunch” rather than generic advice.
Alerts for missed intake daysIf logged protein drops below 80 % of target, Eureka sends a gentle nudge.

Why many Masters runners trust Eureka’s AI doctor for nutrition and beyond

Women using Eureka for menopause rate the app 4.8 / 5 stars, and marathon trainees find the same attentive care.

Privacy-first symptom and diet loggingYour data stay encrypted; only you and the medical reviewers can see it.
Lab ordering without clinic waitsRequest a creatinine or ferritin test; a licensed physician in your state reviews and approves when appropriate.
Fast feedback on supplementsAsk, “Is collagen worthwhile?” and get an evidence-graded answer in under 2 minutes.