What Changes at High Altitude?

Above roughly 3,500–4,000 metres, the human body operates under increasing physiological stress.  Basal metabolic rate typically rises by around 10–25 percent, yet appetite often decreases due to altitude-induced appetite suppression.  At the same time, digestion becomes less efficient, cold exposure increases calorific demand, sleep quality declines and recovery slows.

The result is a well-recognised and persistent issue in high-altitude travel; trekkers and climbers frequently under-fuel, even when food is available.

Guidance from the UIAA Medical Commission (Küpper T et al. UIAA Medical Commission Consensus Statement No.2: Emergency Field Management of Acute Mountain Sickness, HAPE and HACE. UIAA, 2012) highlights adequate energy intake as part of the primary prevention of altitude illness.

The International Society for Mountain Medicine (Viscor, G. et al. (2023).  Nutrition and Hydration for High-Altitude Alpinism: A Narrative Review.  International Journal of Environmental Research and Public Health, 20(4), 3186.) makes general recommendations which include prioritising carbohydrates, maintaining protein balance and a correct hydration status.

The Problem With “Pay-As-You-Go” Meals

Many lower-cost Nepal trekking itineraries place responsibility for food squarely on the client.  In practice, this introduces several predictable and preventable problems.

Tea-house prices increase with altitude due to transport and logistics.  When clients pay for every meal themselves, cost pressure inevitably influences behaviour.  Lunches are skipped, cheaper and less energy-dense options are chosen, meals are replaced with tea or snacks, and portion sizes often shrink as the trek progresses in an effort to conserve cash.  This is not a judgement on individuals; it is a normal response to financial pressure in an already fatigued and demanding environment.

This situation is compounded by the fact that appetite is already suppressed at altitude.  Research shows that appetite commonly decreases even as energy demand increases (Westerterp-Plantenga MS et al. (1999).  Appetite at “high altitude” [Operation Everest III (Comex-’97)]: a simulated ascent of Mount Everest.  Journal of Applied Physiology, 87(1), 391–399.).  When this physiological effect combines with the mental friction of paying for every meal, calorie intake often falls well below what is required to maintain performance.

Sustained calorie deficits at altitude are associated with earlier onset of fatigue, reduced work capacity, increased perceived exertion and poorer pacing on long days.  On objectives such as Mera Peak, where summit day is long, cold and physically relentless, this can become the deciding factor between success and an early turnaround (Butterfield GE et al. Increased energy intake minimizes weight loss in men at high altitude. J Appl Physiol. 1992;72(5):1741–1748.).

Adequate energy intake also plays a crucial role in thermoregulation.  Undereating reduces heat production and increases susceptibility to cold stress, particularly during early-morning summit pushes and time spent at high camps (Castellani JW & Young AJ.  Human physiological responses to cold exposure: Acute responses and acclimatization to prolonged exposure.  J Appl Physiol. 2016;121(3):684–697.).

Nutrition and Acclimatisation: Not a Cure but a Critical Enabler

Food alone does not prevent altitude illness.  However, under-fuelled trekkers are more likely to accumulate fatigue, sleep poorly, dehydrate and struggle to maintain a steady, controlled pace.  All of these factors increase vulnerability to altitude-related problems.  Simply put, well-fuelled trekkers cope better, both physically and mentally.

Duty of Care in High-Altitude Trekking

A guided trek or expedition is not a backpacking holiday.  Professional operators already take responsibility for ascent profiles, accommodation choices, group size, staffing ratios and safety systems.  Nutrition belongs within that same duty of care.

Including meals on a high-altitude trek removes financial pressure from food choices and allows leaders to actively encourage consistent eating throughout the journey.  It promotes steady energy intake across the group, improves resilience and pacing, and reduces avoidable risk.  Importantly, this does not remove choice.  Clients still select freely from tea-house menus; what disappears is the incentive to under-fuel.

The Hidden Cost of “Cheap” Treks

A lower headline price that excludes meals does not eliminate cost; it simply displaces it.  Responsibility shifts from operator planning to individual judgement, from structured risk management to daily decisions made under fatigue, and from prevention to consequence.

In many cases, clients end up spending similar amounts overall but with greater stress, less consistency, a reduced margin for error and a lower likelihood of performing well on demanding days.  At altitude, false economies rarely pay dividends.

This Applies Beyond Mera Peak

While Mera Peak provides a clear example, the same principles apply across most treks and expeditions in Nepal, including Everest Base Camp, the Annapurna Circuit, Island Peak, Lobuche East and any trip involving multiple nights above roughly 4,000 metres.  Wherever altitude, effort, cold and fatigue intersect, nutrition becomes a safety system rather than a lifestyle choice.

A Final Word

If you are comparing treks and an itinerary excludes meals, it is worth pausing to ask whether you have realistically budgeted for three proper meals a day at altitude, whether cost pressure might influence what, or whether, you eat when you are tired, and whether the operator recognises nutrition as part of their duty of care.

At high altitude, the body already has enough to contend with.  Choosing a trek that removes barriers to adequate fuelling is not about comfort or convenience; it is about setting yourself up to perform, acclimatise and finish the journey strong.

Sometimes the cheapest option is only cheaper on the booking page.