Should you eat more carbs at high altitude? A definitive nutritional guide

December 24, 2025 •

4 min read

Studies show that at high altitude, the body's reliance on carbohydrates for fuel significantly increases, primarily because carbohydrate metabolism is more oxygen-efficient than fat or protein metabolism. This makes a high-carbohydrate diet a crucial component for anyone traveling to elevated areas, from trekkers to mountain athletes.

Quick Summary

Yes, increasing carbohydrate intake is recommended at high altitude to improve oxygen saturation and energy levels. The body becomes more reliant on carbs for fuel, while digestion of fats and proteins becomes less efficient. Prioritizing complex carbs, staying hydrated, and eating smaller, frequent meals are key strategies for success at elevation.

Key Points

Increased Carb Reliance: At high altitude, your body relies more heavily on carbohydrates for energy due to increased efficiency in low-oxygen conditions.
Combat Appetite Loss: Appetite is often suppressed at altitude, making small, frequent meals of easy-to-digest, high-carb foods a critical strategy to maintain energy balance.
Choose the Right Carbs: Utilize complex carbohydrates for sustained energy and simple carbohydrates for quick boosts during exertion.
Prioritize Hydration: Increased fluid loss at altitude necessitates high fluid intake, with electrolyte-carb drinks providing both hydration and energy.
Avoid Heavy Fats: Heavy, fatty foods are harder to digest and can cause discomfort, so focus on lean proteins and a higher proportion of carbs.
Improve Oxygen Saturation: Carbohydrate metabolism produces a greater amount of carbon dioxide, which can help increase ventilation and improve blood oxygen saturation.
Support Performance: A high-carbohydrate diet helps reduce perceived exertion and boosts physical performance during high-intensity or prolonged activity at altitude.

The Physiological Rationale for More Carbs at Altitude

When you ascend to high altitude, the decreased oxygen pressure, known as hypoxia, triggers several physiological changes in your body. Your resting metabolic rate increases, and your body preferentially shifts its fuel source towards carbohydrates. This is because carbohydrate metabolism requires less oxygen to produce the same amount of energy (ATP) compared to fat metabolism. Essentially, your body becomes more efficient with the limited oxygen available by relying on its preferred fuel source.

Altitude, Acclimatization, and Metabolism

Initial exposure to high altitude causes a surge in stress hormones like adrenaline and cortisol, which accelerates carbohydrate use for energy. As you acclimatize over several days, your body adapts, but the preference for carbohydrates persists during physical exertion. This is vital for sustaining energy, especially during prolonged or intense activity, where muscle glycogen stores can be rapidly depleted. A high-carbohydrate diet is necessary to replenish these stores and prevent performance drops.

Navigating Appetite Suppression and Digestion Issues

One of the most common challenges at high altitude is a reduced appetite, often accompanied by digestive discomfort. The reasons for this are multi-faceted, including the effects of hypoxia on metabolism and a potential shift in taste preferences. Heavy, fatty meals and large portion sizes can exacerbate these issues because fat takes longer to digest and requires more oxygen for metabolism, diverting blood flow from the gut.

To counteract this, it's recommended to eat smaller, more frequent meals and snacks that are easy to digest. Liquid calories from sports drinks or protein shakes can also be a viable strategy when solid food is unappealing. Planning your nutrition strategy to include foods you enjoy and tolerate well at altitude is critical for ensuring adequate caloric intake and preventing unintentional weight loss, which can compromise physical performance and immune function.

The Right Carbs for High Elevation

Not all carbohydrates are created equal, and your strategy should incorporate both complex and simple carbohydrates for sustained and immediate energy. Complex carbohydrates provide a slow, steady release of energy, which is ideal for foundational fuel throughout the day. Simple carbohydrates offer a quick boost when needed most, such as during a difficult ascent.

Here are some excellent carbohydrate choices for high-altitude environments:

Complex Carbs: Oats, quinoa, brown rice, whole-grain bread, and lentils offer sustained energy and can help with digestive regularity.
Simple Carbs: Dried fruit, honey, energy gels, and chews are perfect for quick, easily absorbed energy during exertion.
Easy-to-Digest Carbs: Tortillas, rice balls, and noodles are often tolerated well, even when appetite is low.
Liquid Carbs: Electrolyte and carbohydrate-based sports drinks help with hydration and provide rapid fuel.

Comparison: High-Carb vs. High-Fat Diet at Altitude


Feature	High-Carbohydrate Diet	High-Fat Diet
Oxygen Efficiency	High. Requires less oxygen for metabolism, making it ideal for hypoxic conditions.	Low. Requires more oxygen for metabolism, which can stress the body in low-oxygen environments.
Energy Source	Preferred and primary fuel source, especially during exercise.	Less efficient fuel source at altitude; can be distasteful to some climbers.
Digestion	Easier to digest, especially when using simple carbs or starchy foods.	Can be harder to digest and contribute to nausea or sluggishness.
Performance Impact	Reduces perceived exertion and improves physical performance during prolonged or intense exercise.	Performance may suffer, especially at higher intensities, as the body prefers carbs for fuel.
Glycogen Stores	Effectively replenishes muscle and liver glycogen stores, which are used more rapidly at altitude.	Ineffective for glycogen replenishment, which can lead to rapid fatigue and muscle catabolism.

Practical Tips for Your High Altitude Diet

Beyond simply eating more carbohydrates, implementing a few key strategies can optimize your nutritional intake for high-altitude success.

The Importance of Frequent Fueling

Instead of two or three large meals, aim for several small meals and snacks throughout the day. This keeps your energy levels stable and is easier on your digestive system, which slows down at altitude. Eating regularly, even when you don't feel hungry, is crucial for maintaining energy balance.

Pre-Expedition Carb-Loading

While at lower elevations, consider a carb-loading strategy in the days leading up to your ascent to maximize muscle and liver glycogen stores. This ensures you start your climb with full energy reserves.

Focus on Hydration

High altitude increases fluid loss due to increased breathing and the drier air, so staying hydrated is paramount. Mix things up by alternating between plain water and carbohydrate-electrolyte drinks to replenish lost minerals and fuel simultaneously. Use hydration tablets or sports drink powders to add flavor if plain water becomes unappealing.

Consider the Cold Factor

Most high-altitude environments are cold. Your body burns additional calories to stay warm, with shivering being primarily fueled by carbohydrates. A high-carb diet helps maintain body temperature, which is essential for preventing hypothermia.

Conclusion: Fueling Your Ascent with Carbs

For anyone venturing to high altitudes, the answer to "should you eat more carbs?" is a resounding yes. Your body's metabolic adaptations to hypoxia make carbohydrates the most efficient fuel source for both performance and acclimatization. By focusing on a strategy that prioritizes easily digestible, high-quality carbohydrates, complemented by adequate hydration and frequent, smaller meals, you can mitigate the negative effects of altitude and maintain your energy and performance.

While protein and fat still play important roles, particularly for recovery and overall caloric intake, a carbohydrate-centric approach is the cornerstone of effective high-altitude nutrition. For more information on the metabolic and physiological effects of high altitude, consult resources from sports science institutions and academic research, such as the Frontiers in Sports and Active Living journal.

Frequently Asked Questions

The body shifts its metabolic fuel towards carbohydrates because carbohydrate metabolism requires less oxygen to produce the same amount of energy (ATP) compared to fat metabolism. This makes it a more efficient fuel source in low-oxygen environments.

While individual needs vary, research suggests a carbohydrate intake of at least 60% of your total energy intake, with some endurance athletes needing more. Focus on a carbohydrate intake of around 6–10 grams per kilogram of body weight per day.

Insufficient carbohydrate intake at altitude can lead to rapid depletion of muscle glycogen stores, causing fatigue, reduced performance, and potentially worsening symptoms of altitude sickness. Inadequate energy intake can also lead to muscle loss.

While there are no carbs to strictly avoid, it's wise to limit excessive intake of highly processed sugary foods that can cause energy spikes and crashes. Focus on whole-food complex carbs for sustained energy.

Yes, a balanced diet is still important. Moderate protein intake is necessary for muscle recovery, and healthy fats provide essential fatty acids. However, the proportion of calories from carbohydrates should be increased relative to your sea-level diet.

When appetite is low, focus on small, frequent meals and snacks. Easy-to-digest options like soups, liquid calories from sports drinks, and simple carbs like dried fruit can be effective. Prioritize palatable foods you enjoy and won't upset your stomach.

Yes, carb-loading in the days before your ascent is a good strategy to maximize your muscle and liver glycogen stores. This provides a crucial energy reserve as you begin your time at elevation.