Climbing up a tall mountain has different nutrition and hydration demands than powering through a workout at your local gym. As we transition into summertime outdoor activities like hiking, staying adequately nourished and hydrated should be top of mind.

The best way to ensure you’re properly fueled (especially at those higher altitudes) greatly depends on the intensity of your hike and what the weather has in store, says Lisa Valente, RD, a registered dietitian and nutrition editor at Healthline.

Bluebird day on the radar? Aside from loading up on the SPF, you may want to pack an extra stick (or two) of your fave electrolyte powder to compensate for the extra sweating and lost hydration you’ll be doing.

Beyond that, here’s what to eat before and after a hike.

How altitude affects your nutrition and hydration needs

Being at higher altitudes affects your hydration and nutrition needs in many ways. For starters, if you find you’re sweating a lot and are running the risk of becoming dehydrated due to the physical activity you’re engaging in, you may want to up your electrolyte intake, particularly on those hot summer days spent well-above sea level.

“In the summer, you will likely sweat more and so make sure to still drink plenty of fluids and choose foods that deliver electrolytes, like sodium, potassium, and magnesium, such as bananas, beans, fish, bread, peanut butter, and seeds,” Valente says. You can also supplement your hydration by adding electrolyte powders or sports drinks into the mix.

Engaging in exercise at higher altitudes also means your body is working harder, increasing the need for adequate hydration and nourishment. “Your hydration needs increase because you’re breathing more trying to get oxygen to your body and losing water as you breathe,” Valente says. “You also need more calories, especially if you’re active all day,” she adds.

Another interesting thing occurs when at higher altitudes, Valente says: Your iron needs become even greater. Research shows that folks who reside in higher altitudes often cope with something called “erythropoiesis,” which is the body’s process of making red blood cells. (Red blood cells help transport oxygen and carbon dioxide in and out of the body.) In turn, this results in an increase in hemoglobin levels¹ and a greater need for iron-rich foods (which are essential for producing hemoglobin, a protein found in red blood cells). Valente recommends opting for foods like red meat, shellfish, and legumes, all of which are good sources of iron, or taking an iron supplement (if needed) during the duration of your stay in the mountains.

Adapt your nutrition based on the intensity of your activity and weather conditions

Whether it’s cold or hot out outside, Valente says your nutritional needs won’t vary all that much. That’s to say, eating nourishing foods and staying hydrated is always important, no matter what. However, certain climates can play a role in how your body may feel throughout the day, Valente says. “In the winter, you might not feel as thirsty as you do in warm weather, but it’s still important to stay hydrated,” she explains.

You may also find that the types of foods you’re eating might vary based on the conditions or the seasons. Read: cozy soup weather in the wintertime and refreshing fruits like watermelon in the summer. “Foods also contribute to your water intake, so soups, smoothies, fruits, vegetables—the water in those counts,” Valente says.

According to Valente, a few groups may have a greater need for protein and adequate hydration while spending time outdoors at higher altitudes (and in general). “Older adults need more water and also have increased protein needs [as they age]. If you’re pregnant or breastfeeding, you also need to drink some more water and get some more calories and protein in,” she says.

Additionally, if you’re going to engage in highly strenuous activity, you’ll want to adjust your nutrition intake as needed. “It’s mostly dependent on how active you are. Is this a recreational day hike where you pack a peanut butter and jelly sandwich and some water, or are you going on a multi-day excursion hiking for several hours every day? You’re going to need more fuel [if that’s the case],” she says.

What to eat before a hike at higher altitudes

According to Valente, eating a hearty breakfast should be the first order of business when getting ready to spend a long day on the mountains. A well-rounded breakfast is a must and should contain the following three key nutrients: complex carbohydrates, protein, and some healthy fats. “That might be eggs on whole-grain toast with avocado or a Greek yogurt parfait made with fruit and granola,” Valente says.

Meanwhile, Brigid Kenny, a ski instructor for the last 20 years and location manager at Beaver Creek Children’s Ski and Snowboard School, says preparation for a big day outdoors starts well before the alarm clock goes off. “My preparation starts with lots of sleep,” Kenny says. Indeed, we know that getting inadequate sleep can have worse repercussions than just waking up on the wrong side of the bed (literally). In fact, sleep deprivation has been linked to decreased stamina ²and quicker exhaustion during physical activity too.

That’s why Kenny doesn’t let anything get in the way of her and a good night’s rest—not even a good ol’ après-hike (at least, not always). “I try to stay away from alcohol the night before a big activity and focus on pre-hydration the day before,” she says. And once Kenny’s has checked off the “get good sleep” and “eat a hearty breakfast” boxes, she does a warm-up routine to help loosen up her muscles “before cranking it to 11,” as she says.

Don’t forget to pack ‘pocket snacks’ for midday fuel

Since you’ll need to stay fueled for several hours on end if spending the whole day outdoors is the goal, Valente recommends staying one step ahead of the game by packing loads of healthy snacks for when your energy levels begin to dip. “Packing snacks is also crucial, think energy bars, trail mix, and fruit,” she says. Additionally, Valente puts a big emphasis on adequate hydration. “Hydration is huge,” she says. “Being active at altitude means you’ll need plenty of fluids, so drink lots of water and pack some with you.”

Meanwhile, before heading out the door, Kenny makes sure to grab “pocket snacks,” which she says are an absolute must. Some of her favorites include: beef jerky, fruit leathers, and Honey Stinger Waffles. In her pack—along with her go-to pocket snacks—you’ll also find a small water bottle at all times. “If you’re thirsty on the hill, that means that you are most likely already dehydrated,” Kenny says.

What to eat after a hike in the mountains

After a long day outdoors, you’ll likely be looking forward to a comforting meal to replenish your depleted energy stores (and a hot bath to soak your aching muscles). Valente’s go-to, after-mountain meal includes a burger, fries, and a good non-alcoholic beer. But some protein, carbohydrates, salt, and hydration are essentially the recipe for success for an after-workout meal, Valente shares. “Everything tastes good after a long day on the slopes or hiking trails, so choosing some foods that are nutrient-rich, but also enjoying your meal and celebrating your day outside is a nice way to end a day in the mountains,” she says.

How to make a homemade electrolyte-rich drink: