fcafotodigital When hunger strikes, filling up on low-calorie foods – like fruits and veggies – is one of the healthiest ways to sate your appetite. Not only are they high in water, so you can eat more of them, but they contain a far greater variety of vitamins, minerals and other healthful compounds than highly-processed choices. While there's no scientific proof for 'negative-calorie' foods – those said to burn more calories than they provide – unprocessed 'whole' foods, especially those that are high in dietary fibre and protein, require the most energy to break down. In a study by Pomona College, 20 per cent of the calories in a whole-food meal were burned during digestion, compared to only 10 per cent in a processed meal.