Plenty of people pick running as their go-to cardio workout to burn calories and shed fat. And for good reason—all you need is a pair of sneakers, and you can do it anytime, anywhere! Running also offers a host of benefits for your body beyond torching cals—it can help lower stress, reduce your risk of heart disease, and strengthen joints, just to name a few.
Now for the bad news: Running outdoors on hot days isn’t a magic bullet for weight loss. The higher calorie burn may be negligible compared to the risks of forcing yourself to run during brutal heat, such as dehydration and overheating, Porcari says.
Running on hot days also increases your rate of perceived exertion (RPE), which means you may feel fatigued more quickly than you would on a treadmill. And while some may see that as a sign your body is working hard, consider this: Not being able to complete your full workout isn’t going to help with your weight-loss efforts. (Here’s how to tell when it’s too hot to train outside.)
A better idea? When temps are soaring, add five minutes or so to your indoor run and bump up the incline slightly, Porcari suggests. Research has proven that a 1 percent incline on a treadmill equals the extra effort that running outside takes. And if you’re looking to truly boost your calorie burn, switch up the super-sweaty slog with speed and incline intervals. “Intervals are a great way to increase calorie expenditure, challenge your body, and mobilize fat stores,” says Anita Mirchandani, R.D, C.D.N., a certified trainer. (Here’s a 24-minute interval routine that melts major calories on the treadmill.)
In the long run, those small amounts of extra calories burned won’t lead to big changes on the scale. If you do see your weight drop dramatically post-run, you can probably thank depleted fluid levels and lost water weight, says Mirchandani. That’s why it’s important to replenish electrolytes and minerals when exercising in warmer temperatures.
Finally, remember: To achieve lasting weight loss, don’t be fooled into eating more than you burned off. “We always think we burn more calories than we actually do,” Mirchandani says. Post-workout, focus on a combo of lean protein and whole grains to help you refuel and feel satiated, she suggests, and stay hydrated since adequate water intake does aid in long-term weight loss.