Hunger and Appetite at Altitude: When the Body Says No but Still Needs Energy

Written By Musa Masala

Here is a post we have been looking to do for years! We are so happy to welcome back Ariadna Lucero. Remember her from her first post?

This time Ari is going to answer probably my biggest question about high altitude physiology: Where’s my appetite??? Ariadna created this downloadable PDF (download it here in Spanish) just for you so you can plan ahead and be aware of what’s going on with you and your companions bodies at altitude. We are proud to present this with Ariadna and her company, ALTA Nutrición.

We believe following these guidelines and keeping aware will make your mountain experience more fun and healthier, thank you Ariadna. Jam Jam!!

Hunger and Appetite at Altitude: When the Body Says No but Still Needs Energy

By Ariadna Lucero

You’re over 4,000 meters above sea level. The wind cuts your face, the water takes forever to boil, and the air feels heavy.

You reach for the food you packed for the expedition, but nothing looks appealing. What you’d eat in seconds at home seems impossible to swallow here.

You don’t feel hungry — yet you know your body needs food.

I’m Ariadna Lucero, an Argentine nutritionist passionate about extreme environments. For years, I’ve studied how the human body works, eats, and adapts in the mountains.

During the last climbing season, I conducted my research at Aconcagua Provincial Park, studying how diet, physical effort, and environmental conditions affect the body composition of high-altitude porters.

Through this series for Musa Masala, I want to share what both science and experience teach us about the connection between nutrition, performance, and life at altitude. And we’ll start with something every mountaineer has felt: that strange moment when your body says “no,” right when it needs energy the most.

Hunger or Appetite — What Really Changes?

We often say that “we lose our hunger” at altitude, but what actually decreases is appetite — the desire to eat — while the body’s energy needs remain the same or even increase.

That’s why climbers often don’t feel like eating, even though their bodies urgently need fuel.

Appetite is a selective, conscious desire to eat, influenced by sensory, environmental, and social factors.
 Hunger, on the other hand, is a physical signal of energy need.

The eating process includes three stages:

  • Hunger, which drives food intake.

  • Satisfaction, when the body signals it has had enough.

  • Satiety, the feeling of fullness that lasts until the next hunger cue.

    This cycle is regulated by a complex network of hormonal, neural, and sensory signals.
    In short, eating is not just about the stomach — it’s about the brain, the senses, and the environment.

The Hormones that Guide Appetite

Among the many hormones involved in appetite control, two stand out: ghrelin and leptin.

The Hunger Hormone

Ghrelin is mainly produced in the stomach and rises when the body needs energy. It’s the signal that tells the brain, “It’s time to eat.”

Its levels increase during fasting and drop after eating. People with less body fat or those who exercise intensely tend to have higher ghrelin levels.

The Satiety Hormone

Leptin works as ghrelin’s counterpart. Produced by fat cells, it signals the brain that energy stores are sufficient.

Acting on the hypothalamus, leptin helps turn off hunger signals and supports overall energy balance. In short, ghrelin switches appetite on, while leptin turns it off.

Together, they maintain the body’s delicate energy balance.

When the Senses Decide

Appetite isn’t triggered by hormones alone — it also depends on how we perceive food.

Our sight, smell, and taste play a decisive role:

  • Sight evaluates color and appearance.

  • Smell judges freshness and palatability.

  • Taste determines acceptance or rejection, with a natural preference for sweet or salty flavors and aversion to bitterness.

  • In mountain environments — cold, dry air, fatigue, and lower oxygen — these sensory signals often fade, making food less appealing even when the body desperately needs energy.

Hypoxia and Appetite: When Oxygen Runs Low

Decades of research have shown that hypoxia — reduced oxygen availability — leads to lower appetite and energy intake. This phenomenon, known as altitude anorexia, appears to be an adaptive physiological response.

In one of the earliest studies, Westerterp-Plantenga and colleagues exposed volunteers to a simulated Everest ascent (8,848 m) in a hypobaric chamber for 31 days, without cold or physical exertion.

As simulated altitude increased, hunger decreased, satiety rose, and meal frequency changed. At around 7,000 m, participants showed a clear disconnect between hunger and the desire to eat — their bodies needed energy but didn’t ask for it.

This reduction in appetite may help lower metabolic demand, but when acute mountain sickness (AMS) develops, this balance breaks down, leading to faster weight and energy loss.

Ghrelin and Appetite at Altitude

Years later, Matu et al. (2017) took this research into the real world during a 14-day Himalayan trek. Twelve healthy participants climbed from 113 m to 5,140 m while researchers tracked food intake, appetite perception, body composition, and ghrelin concentrations.

Results showed a marked decrease in both appetite and energy intake, alongside a specific suppression of acyl-ghrelin, the active form that stimulates hunger. This suggests that hypoxia inhibits the hormonal signals that drive appetite, explaining why the body “stops asking for food” even when it needs it most.

AMS and Eating Behavior

Another study, by Aeberli and colleagues, explored how acute mountain sickness affects appetite.

After a rapid ascent to Capanna Margherita (4,559 m), 22 healthy subjects ate freely while their perceptions of hunger and fullness, digestive hormones, and oxygen saturation were recorded.

Energy intake dropped by 33 % on the second day at altitude. Feelings of hunger decreased, while fullness increased, correlating with AMS severity rather than oxygen saturation levels. Food preferences also shifted — sweet foods remained appealing, while others lost their taste.

Interestingly, dexamethasone treatment, commonly used to ease AMS symptoms, improved appetite and energy intake, reinforcing the idea that AMS itself plays a direct role in appetite loss.

In Summary

Hypoxia disrupts the body’s hunger and satiety signals, reducing appetite even without physical effort.
At the same time, the body’s energy expenditure rises — breathing quickens, the heart works harder, and maintaining body temperature demands more fuel.

It’s a natural contradiction: the body needs energy, yet it doesn’t ask for it.
That’s why, in the mountains, eating isn’t just about hunger — it’s an intentional act of self-care, sustaining the body when its signals are confused

Take the Practical Guide

In the mountains, hunger may hide — but energy remains essential.

If you want to learn how to keep your body strong when your appetite disappears, I’ve prepared a practical guide with real-world tips, food ideas, and strategies to maintain your energy at altitude.

Download it for free here (or here in Spanish) and join a community that shares the same passion: to live, move, and nourish ourselves in the mountains.

Follow Alta Nutricion on Instagram: @altanutrition_ar

References

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