If You're Running to Lose Weight, Here's How Long (and How Hard) Your Runs Should Be

Before we get to run length, there's one important thing to remember about weight loss: you can't leave your diet out of the equation. We can estimate that running burns about 100 calories per mile, according to Elizabeth Lowden, MD, medical director of medical weight management at the Metabolic Health and Surgical Weight Loss Center at Delnor Hospital. That's a huge generalization, she noted, but you can use it to see that you'll have to run a pretty long distance to really burn calories. For that reason, Dr. Lowden said, "Running as the only change in your lifestyle is less likely to make as significant an impact as running and working on dietary habits." Working on both of them, in tandem, will be much more effective.

How do you do that? Weight loss isn't all about calories in and calories out, but you should still try to eat at a slight calorie deficit, consuming fewer calories than you're burning. (It's best to visit a registered dietitian to see exactly how to do this, but you can also use this equation to get a good estimate.)

You should also look at what you're eating, specifically aiming to eat more whole foods and vegetables and fewer sugary products and processed, packaged foods. Drink plenty of water (especially if you're running), and up your intake of protein and fiber as well. Here's more on losing weight and fat through diet.

So, keeping in mind that diet plays a major role in shedding pounds, let's talk about how you can optimize your runs to lose weight.

"Ideally, one needs to be exercising at at least 65 percent of their maximum heart rate for 30-90 minutes to burn calories from fat sources," said Chris McGreer, MS, NSCA, personal trainer and exercise physiologist at Northwestern Medicine Delnor Health and Fitness Center. (Here's how to find your max heart rate.) However, that comes with a ton of caveats. The first and most important factor to look at is your current fitness level. "Running is an incredibly strenuous activity that the body needs to be built up to handle," McGreer told POPSUGAR.

Running is high-impact, full-body, and tough on your cardiovascular system and joints; pushing yourself too hard when you start can quickly lead to injury or, at the very least, extremely uncomfortable runs. Neither of those outcomes is going to help you lose weight; you either won't be able to run or you just won't want to.

If you're just starting, it's imperative that you take things slowly. Start off walking and adding in slow jogging intervals; as you get more comfortable, you can increase the amount of time you spend jogging and work your way up to running the whole time. Once you've established a stable pace, you can start to think about the length of your sessions.

"I have found in my training that short and fast interval runs are more effective for weight loss," McGreer told POPSUGAR. Besides burning lots of calories during the workout, he explained that HIIT workouts also increase something called the EPOC effect (which stands for excess postexercise oxygen consumption), which is the idea that your body is pulling in more oxygen to recover from your workout, and more oxygen means more energy, which means more calories burned, even when you're no longer exercising. This "afterburn effect" isn't going to burn hundreds of calories or last all day, but it does give you a little bump that can help.

Interval runs also give you the chance to get into that fat-burning high heart rate zone without being too hard on your body. "If you're doing interval training, you can get your heart rate to that sweet spot range and back off to recover, then repeat, a number of times," explained Josh Muskin, a CrossFit Level 2 coach who specializes in endurance athletes. "Interval training ensures that the total time in the sweet spot zone longer than what the athlete could sustain in one continuous session." Try this simple 30-minute interval running workout as a start.

Even though interval runs can be great for weight loss, we don't recommend you do them every day; the intensity can still lead to injury or burnout. Mix in a longer, slower-pace run or two to increase your endurance, which will help you perform better on those HIIT runs. And for weight loss especially, consider adding strength training into your routine. Building muscle boosts your metabolism, which means you'll burn more calories throughout the day and not just when you're working out.

While 30- to 90-minute runs and higher intensities can help you lose weight, again, it's important that you work up slowly to those longer distances and faster paces. "You really need to listen to your body," McGreer told POPSUGAR. Even seasoned runners who run daily, he explained, still suffer from overuse injuries like shin splints and knee issues. Take your time and space your runs throughout the week, and (coupled with a healthy diet) your runs will help you see results.