Do hot days leave you feeling listless? There’s a reason—in the sweltering heat, your body must devote much of its energy reserves to maintaining a safe internal temperature, leaving you with little left in the tank for other activities. 

Beyond placing yourself in front of the air conditioner, there are several surprising ways to maintain your ­energy levels when the mercury climbs…

Eat smaller amounts more often. Hot-day dining poses a challenge from an energy perspective. If you eat hefty meals, you will feel tired as your body must devote much of its already heat-drained energy resources to digestion. If you consume fewer calories than you need, the resulting hunger will leave you feeling spent as well. Meals should be comprised of mostly slow-releasing complex carbs such as vegetables and whole grains with a little  protein—roughly a 3:1 or 4:1 ratio of carbs to protein. 

It is best, therefore, to eat small amounts throughout hot days rather than big stomach-filling meals. Or reduce the size of your meals to two-thirds their normal size, for example, and eat healthy snacks in between to make up for the missing calories. Two smart hot-weather snacking options…

Fruit is a great hot-weather snack because it helps you stay hydrated. Not only are most fruits full of hydrating fluid, they’re also high in carbohydrates, which boost glycogen levels. Glycogen improves your body’s ability to retain water. Fruits that are particularly high in carbs include apples, bananas, pineapples, mangoes, watermelon and cherries. 

“Energy gels”—carbohydrate-rich products often consumed by endurance athletes during draining events—provide a hydration-helping glycogen boost, too. And unlike fruit, these small one- to one-and-a-half-ounce packets can be stowed safely for months in pockets, purses and glove compartments, so you can always have one handy when you feel spent on a summer day and need a quick energy fix. Examples: GU Energy Gels ($31.16 for 24) and PowerBar ­PowerGel ($36.99 for 24 packs). Each is available in a range of flavors. Other good options: Honey sticks and honey-sweetened snacks from Honey Stinger.

Cool your neck and the inside of your wrists. Cooling your blood is one of the major energy-draining challenges your body faces on hot days. Your blood circulates right under your skin on your neck and inside your wrists—that’s why you can take your pulse there. When you cool these areas, it makes this chore less demanding, preserving your energy.

One way to cool these areas is to soak a bandana and wristbands in cold water, then tie the bandana around your neck and put the wristbands on your wrists before heading out into the heat. 

For a deeper, more lasting chill, freeze the wet bandana and wristbands before donning them. Or use items specifically designed to hold the cold, such as the Mission Enduracool Reflective Cooling Headband ($14.99) and the Chill Pal 12 in 1 Multi Style Cooling Neck Gaiter Face Cover ($13.97). Instant-cold packs also are helpful to keep in your bag.

If you’re stuck out in the heat without these items, buy a cold beverage in a can or bottle and hold it against your neck and/or the insides of your wrists before drinking. This helps maintain your energy in two ways—the cold container cools your blood…then consuming the drink helps you stay hydrated. As you probably already know, dehydration is a common cause of energy depletion on sweaty days. 

Helpful: If a cold sports drink such as Gatorade or Powerade is available, choose that. If you’ve been sweating, the carbs and electrolytes that it provides truly will help your body restore its hydration and energy levels—that isn’t just empty marketing. For people who want to avoid sugar, a good choice is mineral water, which naturally contains electrolytes, instead of sugary drinks. Or you can eat a piece of fruit. 

Don’t worry about whether you drink caffeinated or noncaffeinated beverages—caffeine ingestion during exercise does not have the diuretic effect commonly believed. But don’t overdo it with caffeinated drinks on hot days either. Soda, iced tea and iced coffee can be tempting beverage options, but excessive caffeine consumption after the morning hours can make it hard to fall asleep. 

Cover up with breathable, sweat-wicking fabrics. People tend to show skin when it’s hot, donning tees, tanks, skirts and shorts that leave their limbs exposed. But even if you use sunscreen responsibly and avoid sunburn, the sun’s heat on that exposed skin can drain your energy over the course of the day. 

If you’re going to be in direct sunlight for a significant amount of time on a hot day, it’s better to cover your limbs with loose-fitting, light-colored garments made from sophisticated synthetic fabrics that are designed to allow heat to escape and wick sweat away from the body. ­Examples: Under Armour Iso-Chill, Arctic Cool and Nike Dri-FIT make garments for men and women. For professional wear, there’s Rhone’s Commuter Dress Shirts for men ($118) and Long Sleeve Delta Pique Polo for men ($92). Lululemon offers Everlux garments for women, such as In Movement leggings ($98).

Also, wear a visor or a brimmed hat made from a a breathable, sweat-­wicking fabric. This will keep you cool by keeping sunlight off your face and won’t trap heat around your head. Example: Under Armour Airvent Iso-Chill Fish Cap, $28.

Keep cool at night to boost ­energy levels during the day. One reason people lack energy on hot days is that they failed to get sufficient sleep the previous night because of the oppressive heat. If you don’t have air-conditioning throughout your home, consider getting a window air conditioner for your bedroom. At a minimum, run a fan in the room while you sleep.

Exercise indoors with fans pointed directly at you. Outdoor workouts are unnecessarily dangerous on hot days. Extended exertion in such steamy conditions could lead to heat stroke, which can cause permanent damage to the brain, heart and/or kidneys—and it even can be fatal. 

On hot days, exercise inside, using equipment such as a treadmill, ­elliptical machine or stationary bike…or with simple exercises you can do anywhere, such as squats, push-ups and planks. But before starting these indoor exercises, set up one or more fans aimed at the spot where you will be doing your workout and set them to high speed. (Be sure to do this even if your home is air-­conditioned.) The breeze will allow your sweat to evaporate, which will cool your skin. 

If you don’t want to skip your outdoor exercise on a hot day, at least schedule it for early in the morning or late evening, when temperatures are cooler. 

Warning: If you experience potential symptoms of heat stroke, such as faintness, dizziness, confusion, rapid heartbeat or rapid breathing, seek hydration right away…bring your body temperature down as quickly as possible with ice packs, cold drinks and/or cool showers…and seek medical attention immediately.