While you can work on your ab muscles in the gym, abs really are made in the kitchen. If you're trying to lose weight, be sure you're eating a healthy, well-balanced diet at a calorie deficit. And to flatten your stomach, load up on these seven dietitian-recommended foods that burn belly fat, such as broccoli, salmon, Greek yoghurt (which you can use in salad dressing, guacamole, and so much more), and beans.