Cardio is key for weight loss, but just how often do you need to get your heart pumping to start shedding pounds? "There's no one-size-fits all here, but as long as you are in a caloric deficit, you will lose weight," K. Aleisha Fetters, MS, CSCS, a personal and online trainer based in Chicago, told POPSUGAR. That means you need to burn more calories without replacing them with your diet.

As a starting point, the U.S. Department of Health and Human Services recommends 300 minutes of moderate-intensity activity each week, noting that those who want to lose a substantial amount of weight — more than 5 percent of their body weight — may need more. "I'd recommend breaking it up over at least five days, but if you can focus on spreading it across all seven, all the better," Fetters said.

If that seems like a huge commitment, it doesn't need to be. For example, Fetters recommends going for a 10- to 15-minute walk after meals, pacing while on a phone call, or running errands on foot instead of driving. "[Those things] combined with workouts that more substantially get your heart rate up — roughly 30 minutes per day — will get the job done," she said.

As for specific workouts, "I recommend cardio in the more moderate to high-intensity range: running, rowing, cycling at high speeds or high resistance," Fetters said — though if you like a low-impact workout like swimming, you should do that. It's also important to pair cardio with strength training — in a 12-week trial, people who combined aerobic and resistance training lost more weight than those who did one or the other. The stronger you become, the more calories you'll burn.

Plus, if you only do cardio, you run the risk of burning muscle instead of fat. "I tend to gravitate toward circuit training when it comes to cardio for fat loss because, by also building muscle, it prevents losing weight from muscle," Fetters told POPSUGAR. "We want to target fat loss, not just weight from any source."