Yes, a healthy burger can exist. Forget apple pie. There’s nothing more American than a burger—Americans eat nearly 50 billion of them every year, so the thought of a summer barbecue without one feels like heresy. If you’re trying to lose weight, you don’t have to skip that juicy, grilled patty at your next barbecue because, with a few tweaks (that don’t sacrifice flavor and actually make it more filling), you can make a healthy burger. There are some easy ways to make your burger better for your heart and your waist. Follow these five tips to cook up a healthy burger: 1. Start with a properly portioned patty. We’re all accustomed to quarter-pounders, but a proper portion of beef is far from it. On Nutrisystem, a PowerFuel serving is two ounces of cooked lean beef. Chances are, if you’re eyeballing the portions when making patties, you’ll overserve yourself: A study, published in Nature , found that people correctly guessed the amount of food in a portion only about half the time,...