Most Salkantay Trek preparation focuses on fitness and gear. Nutrition—perhaps the most consequential variable determining physical performance and recovery—receives minimal attention. Yet the physiology of eating and digesting at 4,650 meters differs fundamentally from sea-level nutrition, creating distinct requirements and challenges.
At altitude, your metabolic rate increases 10-15% due to increased sympathetic nervous system activity and the metabolic cost of hyperventilation. Simultaneously, appetite decreases through multiple hormonal mechanisms, creating a paradoxical situation: your body needs more calories while wanting to eat less.
This metabolic mismatch—increased caloric requirements paired with decreased appetite—represents one of altitude trekking’s most underestimated challenges. Trekkers who address this through informed nutritional strategy perform substantially better, recover more effectively, and experience greater enjoyment than those relying on casual eating patterns.
This comprehensive guide explores the biochemistry of altitude nutrition, quantifies actual caloric requirements on the Salkantay Trek, and provides evidence-based strategies for optimizing macronutrient composition, micronutrient intake, and hydration patterns specific to high-elevation trekking.
Understanding why caloric requirements increase at altitude provides context for nutritional strategy.
At altitude, your resting metabolic rate (calories burned at rest) increases substantially. This elevation results from multiple mechanisms:
Sympathetic Nervous System Activation: Hypoxia (reduced oxygen availability) triggers sympathetic nervous system activation. This system increases heart rate, metabolic rate, and muscle tension—metabolic effects collectively termed the “fight-or-flight response.”
Quantitatively, sympathetic activation increases resting metabolic rate by approximately 5-8% at altitudes above 3,000 meters. By 4,650 meters, this effect intensifies, increasing basal metabolic rate by 8-12%.
Thermoregulation Demands: Despite paradoxical findings (altitude doesn’t always feel cold), your body expends additional energy maintaining core temperature at elevation. Reduced atmospheric pressure and lower oxygen availability impair thermoregulation efficiency. Your body compensates through increased metabolic heat production.
Hyperventilation Costs: The persistent hyperventilation at altitude—your increased breathing rate—requires muscular work from your respiratory muscles. The diaphragm and intercostal muscles continuously work harder, consuming additional calories.
Hormonal Changes: Altitude triggers hormonal shifts including increased cortisol (the stress hormone) and epinephrine (adrenaline). These hormones increase metabolic rate through multiple mechanisms including increased glucose mobilization and fat mobilization.
Combined Effect: Resting metabolic rate at the Salkantay’s elevation increases approximately 10-15% compared to sea level. For an individual whose sea-level resting metabolism consumes 1,500 calories daily, altitude increases this to roughly 1,650-1,725 calories daily at rest.
Exercise metabolic cost increases disproportionately at altitude. The fundamental reason: your muscles must work harder (consume more oxygen) to perform equivalent mechanical work at reduced oxygen availability.
At sea level, hiking uphill at moderate pace might require 60-70% of your maximal oxygen uptake (VO2 max). At the Salkantay’s elevation, the same absolute pace requires 90-100% of your VO2 max—a much greater physiological strain.
This increased physiological strain increases metabolic cost. Research examining energy expenditure during exercise at high altitude shows metabolic costs increase 15-25% compared to equivalent exertion at sea level, independent of the weight-related increases in metabolic cost discussed in previous sections.
Quantitative Example: A 70-kilogram individual hiking for 6 hours at moderate pace at sea level might expend 2,500-2,800 calories. The same 6-hour hike at the Salkantay’s elevation expends approximately 2,900-3,500 calories—a 15-25% increase.
Combining increased resting metabolic rate and amplified exercise metabolic cost, trekkers on the Salkantay Trek typically experience total daily energy expenditure of:
Conservative Estimate: 3,500-4,000 calories per day for average-weight individuals
More Typical: 4,000-4,500 calories per day
Higher Estimate (heavier individuals or aggressive pacing): 4,500-5,500 calories per day
These estimates assume 6-8 hours of hiking daily at moderate pace, typical for multi-day trekking.
The physiological increase in caloric requirements at altitude directly conflicts with appetite suppression—a phenomenon experienced by most high-altitude trekkers.
Multiple hormonal changes reduce appetite at altitude:
Ghrelin Reduction: Ghrelin, produced primarily in the stomach, stimulates appetite. Altitude reduces ghrelin production, partially through hypoxia-induced signaling and partially through altered gastrointestinal blood flow.
Increased Leptin Signaling: Leptin, the “satiety hormone” produced by fat cells, signals fullness and reduced hunger. Altitude increases leptin sensitivity and signaling despite unchanged leptin levels, creating a paradoxical increase in perceived satiety despite unchanged leptin concentrations.
Increased CCK and PYY: Cholecystokinin (CCK) and peptide YY (PYY), gastrointestinal hormones signaling satiety, increase at altitude. These hormones suppress appetite through hypothalamic signaling.
Elevated Cortisol: While cortisol increases metabolic rate, chronic elevation also impairs appetite through effects on appetite-regulating neurons.
Cumulative Effect: These hormonal changes create profound appetite suppression—trekkers frequently report eating 30-50% less than normal, despite increased caloric needs.
Beyond hormonal effects, gastrointestinal function itself becomes impaired at altitude.
The digestive system is metabolically expensive—it normally receives 10-15% of cardiac output to support digestion and nutrient absorption. At altitude, cardiac output becomes constrained (limited by oxygen availability), and blood flow distribution shifts toward brain and heart.
This gastric hypoxia reduces:
Gastric Motility: Stomach contractions that propel food toward the small intestine become weaker, increasing gastric retention time and feelings of fullness.
Intestinal Absorption: The reduced blood flow to the small intestine impairs nutrient absorption efficiency. Some nutrients, particularly minerals requiring active transport, show measurably reduced absorption.
Stomach Acid Production: Acid production decreases at altitude, impairing protein digestion initiation.
Psychological Factors: Appetite suppression is reinforced by psychological factors. The novelty of altitude experiences, altitude-induced malaise when present, and the focused mental demand of trekking all distract from hunger signals.
This appetite paradox creates a crucial challenge: trekkers must consciously consume calories despite lacking hunger signals. This isn’t merely uncomfortable; failure to overcome this tendency leads to cumulative caloric deficit—a deficit that, over 5+ days, produces measurable physiological consequences including accelerated fatigue, impaired recovery, and potentially serious complications.
Understanding that you need 4,000+ calories daily is important, but equally crucial is understanding what composition of those calories optimizes performance and recovery at altitude.
At altitude, your muscles increasingly rely on carbohydrate metabolism (glycolytic pathways) rather than fat metabolism (oxidative pathways). This metabolic shift occurs because carbohydrate metabolism produces ATP (cellular energy) with lower oxygen efficiency than fat metabolism.
Under oxygen limitation, your body shifts toward the less-efficient but less-oxygen-demanding metabolism—carbohydrate metabolism. This metabolic adaptation explains why high-altitude athletes should emphasize carbohydrates.
Optimal Carbohydrate Intake: Research on altitude athletes recommends carbohydrate intake of 6-10 grams per kilogram of body weight daily for intense endurance activity (which high-altitude trekking represents). For a 70-kilogram individual, this translates to 420-700 grams of carbohydrate daily.
If total daily caloric intake reaches 4,500 calories, and carbohydrate provides 4 calories per gram, a 550-gram carbohydrate target represents approximately 60% of total calories—a carbohydrate-dominant diet.
Practical Implementation: Carbohydrate sources should include:
Altitude trekking creates significant muscular demand and disrupts protein synthesis. Additionally, altitude increases protein oxidation—your body burns protein for energy at higher rates than at sea level.
To support muscle recovery despite these challenges, protein intake should increase:
Recommended Protein Intake: 1.4-1.8 grams per kilogram of body weight daily for altitude activities. For a 70-kilogram individual, this represents 98-126 grams of protein daily.
This represents a higher protein intake than typical lowland recommendations (0.8-1.0 grams per kilogram) for sedentary individuals, reflecting the increased protein demands of high-altitude trekking.
Timing Considerations: Protein synthesis peaks following exercise and during the early sleep period. Consuming protein within 1-2 hours post-hiking and before sleep optimizes recovery. Breaking protein intake across multiple meals (rather than consuming all protein at one meal) also improves amino acid availability for protein synthesis.
Practical Implementation: Protein sources for trekking include:
Fat provides 9 calories per gram—more than twice the caloric density of carbohydrates or protein. This caloric efficiency makes fat attractive for weight-conscious nutrition planning. However, fat presents challenges at altitude:
Reduced Digestibility: The gastrointestinal dysfunction at altitude impairs fat digestion more than carbohydrate digestion. High-fat meals increase feelings of fullness without proportional energy delivery due to poor absorption.
Increased Gastric Retention Time: Dietary fat slows gastric emptying, increasing the time food remains in the stomach. This contributes to fullness and can trigger nausea.
Recommended Fat Intake: Despite fat’s caloric density, limiting fat to 20-25% of total calories at altitude proves more effective than attempting to maximize fat intake. This typically represents 100-125 grams of fat daily for 4,500-calorie intake.
Fat Source Selection: Emphasize easily-digestible fats:
Avoid excessively fatty foods like fried items, high-fat meats, and cream-based dishes—these increase GI distress without proportional benefit.
Synthesizing the above recommendations, optimal macronutrient distribution for high-altitude trekking appears to be:
Carbohydrates: 55-65% of total calories (400-550 grams daily for 4,500 calories)
Protein: 15-20% of total calories (110-130 grams daily)
Fat: 20-25% of total calories (100-125 grams daily)
This carbohydrate-emphasized distribution differs from popular “balanced” recommendations emphasizing equal macronutrient distribution. The altitude-specific optimization prioritizes the metabolic reality that carbohydrates provide the most efficient energy at oxygen-limited conditions.
While macronutrients provide energy, micronutrients enable metabolic processes and support recovery.
Iron deficiency impairs oxygen-carrying capacity through reduced hemoglobin synthesis. At altitude where oxygen is already limited, adequate iron becomes particularly important.
Pre-trek, serum ferritin testing provides useful information. Ferritin levels above 50 ng/mL indicate adequate iron stores. Levels below 30 ng/mL suggest iron supplementation consideration.
Iron Sources:
For trekkers with low baseline iron, supplementation with 25-50mg elemental iron daily for 4-6 weeks before the trek improves baseline hemoglobin and iron stores.
B vitamins function as cofactors in enzymes catalyzing energy metabolism. Altitude increases carbohydrate metabolism, which depends heavily on B vitamins—particularly B1, B2, B3, and B5—for glycolytic enzyme function.
While frank B-vitamin deficiency is rare, suboptimal intake impairs metabolism efficiency.
B Vitamin Sources:
A B-complex supplement containing 100% daily values of major B vitamins, taken beginning 2-4 weeks before the trek, ensures adequate B-vitamin status.
High altitude increases oxidative stress—the production of reactive oxygen species (ROS) that damage cellular structures. Antioxidants neutralize ROS, reducing cellular damage.
Key altitude-relevant antioxidants include:
Vitamin C: Supports immune function and collagen synthesis (important for musculoskeletal recovery). Requirement increases at altitude.
Vitamin E: Lipid-soluble antioxidant protecting cell membranes.
Carotenoids and Polyphenols: Plant-derived antioxidants from colorful fruits and vegetables.
Practical Implementation:
Altitude increases urinary sodium excretion, predisposing toward electrolyte imbalance. Additionally, vigorous hiking and potential heat production increase sweat loss.
Maintaining sodium balance supports:
Implementation: Include modest salt additions to meals beyond personal preference. Sports drinks containing sodium provide both carbohydrates and electrolytes during hiking.
Proper hydration at altitude requires understanding how altitude changes fluid balance and how to drink effectively despite decreased thirst.
Altitude paradoxically decreases thirst perception despite increasing fluid losses through increased urination and possibly increased respiration. This thirst-loss occurs through multiple mechanisms:
Reduced Peripheral Blood Flow: Altitude reduces blood flow to skin, reducing osmoreceptor activation that normally triggers thirst.
Hormonal Changes: Hormone shifts at altitude, including changes in vasopressin signaling, reduce thirst perception.
Practical Consequence: Relying on thirst cues leads to insufficient hydration. Trekkers must drink according to schedule rather than thirst signals.
Baseline fluid requirement at altitude increases due to increased urination and potentially increased respiratory water loss.
General Guideline: 3.5-4.5 liters of fluid daily during hiking days at Salkantay elevations, substantially higher than the often-cited “8 glasses per day” at sea level.
This accounts for:
Urine color provides practical feedback: pale urine indicates adequate hydration; dark yellow/amber urine indicates insufficient fluid intake.
Plain Water: Adequate for hydration maintenance but provides no calories or electrolytes. Pure water consumed in large quantities actually increases urination further through osmotic diuresis—the opposite of desired effect.
Sports Drinks: Containing 6-8% carbohydrates and electrolytes (particularly sodium), sports drinks optimize fluid absorption and retention while providing calories. Studies on high-altitude athletes show that carbohydrate-electrolyte beverages improve both hydration status and sustained performance compared to plain water.
Electrolyte Solutions: Sodium-containing fluids enhance fluid absorption through the sodium-glucose cotransporter in the small intestine. This mechanism increases both carbohydrate and fluid absorption efficiency.
Practical Implementation:
Paradoxically, excessive water consumption can cause problems. Consuming large volumes of plain water without adequate sodium can dilute blood sodium, causing hyponatremia (low blood sodium)—a potentially dangerous condition.
Warning signs include:
Prevention involves:
Implementing the principles above requires a practical daily structure.
Breakfast (before hiking):
Mid-morning Snack (during hiking):
Lunch (during hiking rest):
Afternoon Snack (during hiking):
Dinner (evening):
Evening Snack (before bed):
Total Daily Target: 4,000-4,500 calories with macronutrient distribution as previously outlined
High Reward-to-Weight Foods:
Palatability at Altitude: Foods that taste good at sea level sometimes taste metallic or unappetizing at altitude. Preferences become highly individual.
Strategies:
Guided Trek Considerations: Most guided Salkantay treks provide meals. Understanding provided meal composition and timing allows strategic supplementation if needed. Requesting meals with higher carbohydrate emphasis or additional snacks often requires only advance communication with trek operators.
Despite best intentions, some trekkers experience gastrointestinal distress at altitude.
Gradual Meal Introduction: Begin with small meals, gradually increasing portion sizes as your GI system adapts.
Hydration Before Food: Drinking fluids before eating prevents excessive food volume that triggers fullness.
Ginger and Peppermint: These botanical compounds reduce nausea. Ginger tea or peppermint candy may help.
Avoid High-Fiber Overload: High-fiber foods, while healthy, can increase bloating and GI distress when introduced suddenly at altitude.
Smaller, Frequent Meals: Rather than three large meals, consume five to six smaller meals spaced throughout the day. This reduces gastric distension and associated discomfort.
If GI issues develop:
While whole-food nutrition should dominate, some supplements merit consideration:
Altitude-Relevant Supplements:
Iron Supplement: If baseline ferritin low (for women and individuals with iron-poor diets)
B-Complex Vitamins: For assurance of adequate B-vitamin status
Ginger Extract or Ginger Candy: For nausea management
Electrolyte Powder: For convenient addition to water
Multivitamin: Basic insurance, though unnecessary if diet is nutritionally adequate
Questionable Supplements:
Coca Leaf Preparations: While traditional in Peru, scientific evidence for performance benefit at altitude remains limited. Potential legal considerations exist in some countries.
Altitude Sickness Supplements: Most have limited scientific support. Evidence-based medications (acetazolamide) are preferable for altitude sickness prevention.
Avoid:
Nutrition often receives inadequate attention in Salkantay Trek preparation despite being one of the most controllable variables determining performance and enjoyment.
Understanding that altitude increases caloric requirements 10-15%, that appetite simultaneously decreases, and that this paradox can be overcome through informed nutritional strategy allows trekkers to consciously manage this critical variable.
Implementing carbohydrate-emphasized macronutrient ratios, ensuring adequate protein and micronutrient intake, maintaining proper hydration through scheduled drinking, and strategically addressing gastrointestinal challenges positions trekkers for sustained energy, effective recovery, and greater success on the Salkantay Trek.
For many trekkers, nutrition optimization—often overlooked in favor of fitness preparation—proves equally or more important than cardiovascular fitness in determining trek success. By implementing the evidence-based strategies outlined in this guide, you position yourself for optimal performance from day one through post-trek recovery.
