What this solves
Most trekkers dramatically under-fuel above 4,500 m. Appetite suppression at altitude is real — but so is the energy demand. A 70 kg trekker carrying 15 kg above 4,500 m burns 4,000-4,800 kcal on a Tanggu La summit day. The tool tells you the actual number, plus a macro split that favours carbs (60-70%) because carb oxidation at altitude is more efficient than at sea level.
Tell me about today
How to read the result
The number at the top is your total daily energy expenditure — kcal burned including BMR, the walk, and altitude elevation. The macro bar splits this into carbs / protein / fat.
At altitude, the body preferentially burns carbs over fat. The macro split is therefore skewed: 65% carbs / 17% protein / 18% fat. For a 4,500 kcal day, that's about 730 g carbs — much more than you'd eat at home.
Reference: FAO/WHO/UNU 2001 basal metabolic formulas (Schofield) + ACSM altitude adjustment + Brooks et al. 1991 trek studies.
Limitations
FAQ
A: At 60 kg with a 12 kg pack, 6 hours at 4,500 m, terrain 2 — about 3,300 kcal. Not 4,000, but still 30% above what you'd eat at home.
A: To a point. Aim for at least 70% of the recommended intake. Liquid calories (Nuts & Honey drink, hot cocoa, congee) are easier to consume at altitude than solid food.
A: At extreme altitude (> 5,500 m, sustained) yes — the body breaks down muscle for energy. At Yading altitudes (3,700-5,900 m), this is minimal if you eat enough.
A: Yes, but the body is less efficient at burning fat at altitude. Keep fat for satiety and calorie density (nuts, cheese, salami). Don't try a keto diet at altitude.