5 Tips to Fend off Holiday Weight Gain #1 Sip on soup. Soup is a low energy dense food, which means it provides fewer calories per gram - therefore you can eat a nice serving of soup, relatively low in calories. Having a cup of broth-based soup before a meal can help fill you up, so you don't overindulge in higher-calorie foods. Bonus Tip: eat soup 30 minutes before your main meal to let your stomach register your food, helping to eat smaller portions of the more calorie-den