Fueling Your Heat Defenses: The Power of Hydration & Produce  

We all know what it feels like to struggle through a hot summer day, but have you ever wondered why heat can leave you feeling drained, sluggish, and uncomfortable? While everyone feels the effects of high temperatures, some people are more vulnerable than others.

Drawing on more than 30 years of clinical experience, I’ll explain how your body responds to heat and share practical hydration and nutrition strategies to help you stay cool, hydrated, and energized all summer long.

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How Your Body Protects Itself from Heat

Your body works hard to keep its internal temperature within a healthy range—about 97.7°F to 99.5°F (36.5°C to 37.5°C). This temperature range allows your body’s enzymes and metabolic processes to function properly.

When temperatures rise, your body relies on two main cooling mechanisms:

• Vasodilation, which widens blood vessels near the skin to release heat
• Sweating, which cools the body as sweat evaporates from the skin

On humid days, however, sweat evaporates more slowly, making it harder for your body to cool itself effectively.

Your body also adapts in other ways. It naturally lowers energy expenditure and muscle tension to reduce heat production. That tired, sluggish feeling many people experience in hot weather is actually your body’s way of encouraging you to slow down, rest, and seek shade.

Common Signs That Heat is Affecting You

Spending long periods in high temperatures can lead to symptoms such as:

• Fatigue
• Difficulty concentrating
• Reduced productivity
• Feeling unwell, unmotivated, or irritable
• Physical weakness

Who is Most Vulnerable to Heat?

Those who have the hardest time tolerating heat include:

• Infants and young children
• Pregnant women
• Older adults
• People with chronic conditions such as asthma, diabetes, or heart disease
• People with infections, fever, vomiting, or diarrhea
• Individuals consuming alcohol
• Athletes and people doing strenuous physical work
• People who are sleep-deprived or overtired
• Anyone spending extended time in direct sunlight, such as beachgoers, outdoor athletes, agricultural workers, or construction workers

Why Staying Hydrated Matters

Hydration is one of the most important ways to protect your body in hot weather.

As you sweat, you lose both water and electrolytes. Replacing these losses helps your body continue regulating its temperature and prevents dehydration. Without enough fluids, your cooling system becomes less effective, causing body temperature to rise and increasing the risk of heat-related illness.

Hydration becomes especially important during intense physical activity, which generates additional heat inside working muscles. To cool itself, the body increases sweat production and relies on sweat evaporation to remove excess heat.

Athletes typically lose between 0.5 and 2 liters of fluid per hour through sweat, although losses can be much higher in hot and humid conditions. During prolonged, strenuous activity, some athletes may lose 2.5 to 5 kilograms (5.5 to 11 pounds) of body weight, primarily from fluid loss.

Even modest dehydration can affect physical performance and concentration. A loss of about 4% of body weight through sweating can significantly increase the risk of heat stress and heatstroke. Heatstroke is a medical emergency in which the body’s cooling mechanisms can no longer keep up with rising temperatures. When core body temperature reaches approximately 105.8–107.6°F (41–42°C), widespread damage to cells and tissues can occur throughout the body, particularly in the brain. Severe heatstroke can also damage vital organs, including the liver and kidneys, and may be life-threatening.

Because the body has very limited water reserves, fluid losses must be replaced regularly. One simple way to monitor hydration is by checking your urine color. Pale yellow urine generally indicates good hydration, while small amounts of dark-colored urine can signal that you need more fluids.

Smart Hydration Choices

Not all beverages are equally helpful when temperatures climb. Choose drinks that support hydration and replace lost fluids.

Recommended Fluids

• Clean, safe tap water
• Still (non-carbonated) bottled water
• Freshly squeezed lemonade
• Fresh fruit and vegetable juices
• Chilled tea
• Milk and yogurt
• Sports drinks containing sodium, potassium, and glucose during prolonged physical activity

Limit or Avoid 

• Water from uncertain sources while traveling
• Sparkling water during vigorous physical activity if it causes bloating or discomfort
• Soft drinks
• Fruit drinks with added sugars
• Alcoholic beverages
• High-fat, high-sugar milkshakes
• Energy drinks

Note: For most people, water is the best choice. Sports drinks are generally only needed during prolonged or intense exercise.

What Should You Eat During Hot Weather?

When temperatures soar, focus on foods that are rich in water, vitamins, and minerals. Lighter meals are typically easier to digest and place less strain on the body than heavy, high-fat foods.

Choose More

• Fresh vegetable salads featuring cucumbers, tomatoes, peppers, lettuce, and cabbage
• Boiled, steamed, roasted, or lightly sautéed vegetables
• Lean proteins such as fish, seafood, chicken, turkey, eggs, beans, lentils, tofu, and low-fat dairy
• Fresh fruit, including berries, peaches, watermelon, melon, grapes, and tropical fruits
• Whole grains such as whole grain bread, brown rice, and whole wheat pasta
• Small amounts of healthy oils
• Fresh herbs and lemon juice for flavor

Limit

• Heavy creamy dressings
• Fried or breaded vegetables
• Fatty meats such as bacon and sausage
• Chips and other high-fat snack foods
• Rich desserts such as cakes, pastries, and donuts
• Foods prepared with large amounts of butter, oil, or cream-based sauces
• Extremely spicy foods if they worsen heat discomfort

For more salad inspiration, explore our salad recipes.

Why Fruits & Veggies Are Summer Superstars

They’re Naturally Hydrating

Most fruits and vegetables contain a large amount of water, helping you meet your fluid needs while providing important nutrients.

Examples include:

They’re Rich in Vitamin C

Many fruits and vegetables—including citrus fruits, peppers, kiwifruit, tomatoes, broccoli, and berries—provide high concentrations of vitamin C, an antioxidant that helps protect cells from free radicals generated during heat stress.

They’re Packed with Potassium

Potassium is lost through sweat, making it especially important during hot weather. Fruits and vegetables are excellent sources of this key mineral. For example, a medium banana provides about 420 mg of potassium, while a baked potato contains approximately 610 mg.

They Provide Protective Phytochemicals

Fruits and vegetables contain naturally occurring plant compounds called phytochemicals. Many of these compounds have antioxidant and anti-inflammatory properties that protect cells from damage and help your body recover from the stress caused by high temperatures.

They’re Nutrient-Dense and Naturally Low in Fat

Fruits and vegetables are naturally low in fat and calories, helping support healthy energy intake while promoting satiety. At the same time, they provide essential nutrients without adding unnecessary digestive or metabolic strain during hot weather.

Summary: Stay Cool with Hydration & Produce

When the weather heats up, staying hydrated and choosing the right foods can help your body work more efficiently.

Your body depends on an adequate supply of fluids to support sweating and other natural cooling processes. At the same time, water-rich fruits and vegetables provide hydration, potassium, vitamin C, and beneficial plant compounds that help support overall health during hot weather.

By filling your plate with colorful produce and replacing heavy meals with lighter, nutrient-rich options, you can stay more comfortable, energized, and hydrated throughout the summer.