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It's Too Darn Hot: How Heat Affects Your Appetite

By Cheryl Forberg, RD
Image of Confetti Quinoa Salad with Pistachios and Currants
The heat waves passing through at this time of year tend to bring up questions in people's minds about whether they should change their eating habits when it’s hot. Some of the questions I hear in the summer are:
  • Do our calorie needs change?
  • Does our metabolism go up when it's hot?
  • Does our appetite decrease?
Do our calorie needs change or does our metabolism increase during the hot summer temps? Well, maybe yes, but probably no. Our bodies are well-tuned to keep things at status quo. If anything, our metabolism may go up when we're cold, as our bodies need to work harder to maintain our temperature (by shivering). In the heat, our bodies actually slow down a bit to try to conserve energy so as not to overheat. But none of this really makes any significant change in how many calories our body needs.

What is important to note is that in hot weather your body is prone to dehydration and this is what has an effect on your metabolism. In the course of an average day, sweating, breathing, and waste elimination together leach more than 10 cups of water out of your body - and that's without exercise. If you don't replace what you've lost, you may become dehydrated; and your system literally begins to dry out.

Dehydration lowers your body's energy levels, too. Because our blood is mostly water, when you're dehydrated, the volume of your blood diminishes, lowering amounts of oxygen and nutrients that reach your tissues. Recent studies show there's a trickle-down effect on metabolism: dehydration slows your system to such an extent that you burn fewer calories than you would otherwise during the course of the day. And dehydration can cause other undesirable symptoms, including headache, dizziness, muscle weakness, and a dry, sticky mouth.

Some people say that their appetite decreases when it's hot outside. If that's the case, you should still try to eat small, frequent, healthy meals throughout the day. The takeaway here: When it's hot outside, drink plenty of water, and try to maintain your meals and snacks routine.

When it's super-hot outside, try not to exercise during the hottest part of the day, especially if you're exercising outdoors. Early morning and evenings are your best bet. To make sure your body doesn't overheat, monitor your heart rate. Some people invest in a simple heart rate monitor. It's also important to wear the appropriate workout attire. Don't wear sweats or heavy clothes while working out when it's hot. Sweating more doesn't help you burn more calories; it just may dehydrate you more. And most important, as I already mentioned, stay hydrated!

In terms of mealtime, not only are chilled meals such as salads and gazpacho a refreshing choice – it’s an added bonus that they help to keep your house cool since you don’t have to turn on the stove or oven. Here is one of my favorite meals on a hot summer day!

Confetti Quinoa Salad with Pistachios and Currants
This is a perfect dish to take to a potluck, since it can be made in advance.
Makes 4 large servings

2½ cups Cooked Quinoa

For the Dressing:
1 tablespoon Balsamic Vinegar
1½ teaspoons Lemon Juice
1½ teaspoons Dijon Mustard
2 tablespoons Grapeseed Oil

For the Salad:
1 cup (about 6 ounces) Roast Chicken, shredded
½ cup Dried Currants
1/3 cup Red Onion, minced
3 tablespoons Pistachios, coarsely chopped
2 tablespoons Fresh Basil, chopped
2 tablespoons Fresh Mint, chopped
1 tablespoon Fresh Lemon zest
¼ teaspoon Salt
¼ teaspoon Ground Black Pepper

Image of Measure cooked quinoa into a medium mixing bowl
Measure cooked quinoa into a medium mixing bowl.

Prepare dressing:
Image of In a small bowl, whisk together vinegar, lemon juice and mustard. Whisk in oil until emulsified
In a small bowl, whisk together vinegar, lemon juice and mustard. Whisk in oil until emulsified. Set aside.

Image of Add dressing and remaining ingredients to the quinoa and mix well
Add dressing and remaining ingredients to the quinoa and mix well. Serve immediately.

Nutritional information (per serving):
Calories 350
Calories from Fat 110
Total Fat 12g
Sat Fat 1 g
Trans Fat 0 g
Cholesterol 42 mg
Sodium 240 mg
Carbs 43 g
Fiber 5 g
Sugars 15g
Protein 20 g
Vitamin A 2%
Vitamin C 8%
Calcium 6%
Iron 15%

Modified with permission from A Small Guide to Losing Big by Cheryl Forberg RD (Flavor First LLC).
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