Cross-Country Skiing Nutrition and Supplements: Energy Needs, RED-S and Testing

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Training camp, late October. A dozen junior skiers come in from a three-hour roller-ski session and empty the kitchen: two plates of pasta each, bread, yogurt, fruit, then back for more. Their coach watches one quiet athlete who took half a plate and skipped dessert again. That scene captures cross-country skiing nutrition: this sport has some of the highest energy needs ever measured, and the biggest risk isn’t eating the wrong thing, it’s not eating enough. This page covers how much skiers need, what to eat, the warning signs of under-fueling (RED-S), and an honest look at supplements, for every level from club kids to Olympians and adult marathoners.

General information, not a diet plan. For personal advice, talk to a doctor or a registered dietitian (ideally a sports dietitian, CSSD). Back to the cross-country skiing hub.

How much energy do cross-country skiers need?

A lot. A classic 1994 study used doubly labeled water, the gold-standard method, to measure elite Swedish skiers during a training week. Daily energy expenditure ranged from about 15.1 to 20.2 MJ in the women (roughly 3,600 to 4,800 kcal) and 25.4 to 34.9 MJ in the men (roughly 6,100 to 8,300 kcal). The skiers matched intake to expenditure across the week, but not day by day. The Compendium of Physical Activities puts moderate cross-country skiing at about 8.5 METs and racing at 14 to 16 METs, among the highest values for any sport.

A recreational skier doing an hour on the trails doesn’t need anything like that, but a high school racer training twice a day at camp, a college skier or an adult preparing for a 50 km marathon may need far more than they think.

Daily carbs and protein

The joint position stand of the American College of Sports Medicine (ACSM), the Academy of Nutrition and Dietetics and Dietitians of Canada scales carbohydrate to training load, in grams per kilogram of body weight per day:

Load	Carbohydrate	For a 65 kg (143 lb) skier
Light (technique, easy days)	3–5 g/kg/day	195–325 g
Moderate (about 1 hour a day)	5–7 g/kg/day	325–455 g
High (1–3 hours a day)	6–10 g/kg/day	390–650 g
Very high (4–5 hours a day)	8–12 g/kg/day	520–780 g
Protein (all athletes)	1.2–2.0 g/kg/day	78–130 g

Real skiers often fall short. In a Finnish study of young female skiers, 74% didn’t meet carbohydrate recommendations at home (they averaged 5.0 g/kg a day) and 63% missed them even at training camp. Skiers with better nutrition knowledge ate more carbohydrate and had better energy availability. Build meals around rice, pasta, potatoes, bread, oats, fruit and dairy, add protein at every meal (15–25 g after training, per the same position stand), and keep snacks in the bag for long days. What to eat on the day itself is on our ski day and race day page.

RED-S: when skiers don’t eat enough

The 2023 International Olympic Committee (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs) explains that when energy intake doesn’t cover training, the body cuts back: hormones, bones, immunity, mood and performance suffer, in men as well as women. Cross-country skiing has the ingredients: huge training loads, cold weather that blunts appetite, long days with little time to eat, and a culture that can prize being light on climbs.

The studies show it’s common. In the Finnish study of young female skiers, energy availability was in the optimal range for only 11% at home (42% at camp). A 2024 study of highly trained male skiers found low energy availability on typical training days in the preparation period, with the authors warning that the risk is underestimated by coaches and athletes. Signs worth a doctor’s visit:

• Constant tiredness, or performance that drops even though training is going well.
• Frequent colds and infections, slow healing.
• Missed, irregular or stopped periods (never a “normal” part of training).
• Stress fractures or bone pain.
• Low mood, irritability, poor sleep, low sex drive, or constant worry about food and weight.

Parents and coaches: talk about fueling for performance, not weight, and get help early from a doctor and a sports dietitian. For the overall recovery picture, see cross-country ski recovery.

Iron, altitude and the cold

The ACSM position stand notes that female athletes have higher iron needs, and that low energy intake affects iron status. Skiers who train at altitude camps should ask their doctor about checking iron beforehand. Don’t self-prescribe: UEFA’s expert group on nutrition warns that routine iron supplementation “can do more harm than good” without a confirmed need. At altitude, the CDC lists loss of appetite among symptoms of acute mountain sickness, so easy-to-eat carbohydrate helps in the first days. In the cold, warm meals and drinks are easier to get down than cold snacks.

Supplements: food first, and the testing rules

The IOC consensus statement on dietary supplements (2018) and UEFA’s 2021 expert group agree on the basics: food first; a few supplements have good evidence; many don’t; contamination is a real risk. In one study UEFA cites, about 15% of 634 supplements from 13 countries contained prohormones not listed on the label. Skiers tested by FIS, national anti-doping agencies, college programs or the Olympic movement are responsible for anything found in their sample, so:

• Choose third-party tested products: NSF Certified for Sport or Informed Sport. They lower the risk of contamination; they don’t prove a product works.
• Check medicines too, including asthma inhalers, on Global DRO (globaldro.com) and with your doctor.
• Follow the label dose. We don’t give dosing advice beyond it.
• Skip fat burners and “anabolic” or testosterone products. That’s where banned substances turn up, and they work against the fueling skiers need.

Sports drinks, gels and electrolytes

Listed as sports foods by both the IOC and UEFA, and the most useful “supplements” for long sessions and marathons. Nuun Sport tablets give 300 mg sodium with 1 g sugar and are Informed Choice certified. Skratch Labs Hydration gives about 400 mg sodium and roughly 19 g carbs a scoop (the maker says NSF Certified for Sport, but we couldn’t find it in NSF’s public database, so tested athletes should check). Maurten Gel 100 has 25 g carbohydrate per gel; the maker says it is Informed Sport certified, which tested athletes should confirm in the registry. See best electrolyte powders and best energy gels.

Caffeine

Among the supplements with stronger evidence for endurance, usually taken as coffee. Responses vary, and side effects include anxiety, nausea, poor sleep, tremor and a racing heart, so it’s a poor fit for people with heart problems or rhythm issues, during pregnancy, and for anyone sensitive to it. Check caffeine per serving on any gel or drink. The American Academy of Pediatrics says energy drinks have no place in kids’ and teens’ diets.

Protein, creatine and multivitamins

Protein powder is a convenience, not a necessity: Thorne Whey Protein Isolate (21 g protein per serving) is NSF Certified for Sport. Creatine has good evidence for strength and repeated hard efforts, but UEFA notes it typically adds 1–2 kg of body mass, a trade-off endurance skiers weigh carefully; Thorne Creatine is NSF Certified for Sport, and the AAP recommends against creatine for athletes under 18. A multivitamin such as the Klean Athlete Klean Multivitamin (NSF Certified for Sport) can fill gaps, but isn’t a substitute for food or for testing a suspected deficiency. See best protein powders, best creatine and best multivitamins for athletes.

Product	What it is	Third-party testing	About per serving
Nuun Sport	Electrolyte tablet, 300 mg sodium	Informed Choice	about $0.48 a tablet
Skratch Labs Hydration	Electrolyte drink, ~400 mg sodium	Maker says NSF; not found in NSF database (Oct 2026)	$1.20 ($23.95 / 20)
Maurten Gel 100	Energy gel, 25 g carbs, no caffeine	Informed Sport (maker; confirm in registry)	$4.16 ($49.90 / 12)
Thorne Whey Protein Isolate	21 g whey protein	NSF Certified for Sport	$2.17 ($65 / 30)
Thorne Creatine	5 g creatine monohydrate	NSF Certified for Sport	$0.49 ($44 / 90)
Klean Multivitamin	Multivitamin, no iron listed	NSF Certified for Sport	$1.53 (about $46 / 30)

A big training day of eating (example)

• Breakfast: oatmeal with milk, banana and honey; eggs on toast; juice.
• Morning session (2–3 h): sports drink and a gel or bar each hour after the first.
• Right after: chocolate milk or a recovery shake, a sandwich.
• Lunch: rice or pasta, chicken or fish, vegetables, bread.
• Afternoon session: a snack 1–2 hours before (yogurt and fruit, a bagel).
• Dinner and evening: a full plate with potatoes or pasta and protein, plus a bedtime snack such as cereal and milk.

Adjust to your load: on easy days, eat less carbohydrate; on long or double days, more. More reading: cross-country ski training, injuries, and for comparison soccer nutrition and alpine skiing nutrition.

Cross-country skiing nutrition: FAQs

How many calories do cross-country skiers burn?

Elite skiers in a doubly labeled water study used about 3,600–4,800 kcal a day (women) and 6,100–8,300 kcal a day (men) during a training week. Recreational skiers need much less, but cross-country skiing is one of the most energy-hungry sports per hour.

What is RED-S and why does it matter for skiers?

Relative Energy Deficiency in Sport happens when you eat too little for your training. It affects hormones, bones, immunity, mood and performance in both sexes. Studies find low energy availability is common in skiers, so watch for constant fatigue, frequent illness, missed periods and stress fractures, and see a doctor.

Should cross-country skiers take iron?

Only if a doctor finds you need it. Female athletes have higher iron needs and altitude camps raise questions, so testing makes sense, but routine iron supplementation can do more harm than good without a confirmed deficiency.

What does third-party tested mean?

Programs like NSF Certified for Sport and Informed Sport test products for banned substances and check what’s on the label. It lowers the risk of a positive test from contamination, but it doesn’t eliminate it or prove the product works.

Do young skiers need supplements?

Rarely. Enough food, regular meals and snacks around training cover most needs. The AAP recommends against creatine under 18 and says energy drinks have no place in kids’ and teens’ diets. Talk to a doctor or sports dietitian if you’re unsure.