Vermicelli is a high-energy-dense food. Energy density refers to the number of calories a food contains compared to its weight. The vermicelli contains 3.5 calories per gram; compare that to a low-energy-dense food such as broccoli, which has 0.5 calories per gram. High-energy-dense foods are not as filling as low-energy-dense foods, and if you're not careful you might eat more calories than you intended. Eating the vermicelli as part of a broth-based soup, such as the Vietnamese pho, can help fill you up so you eat fewer noodles.