But shifting belly fat is not the easiest thing in the world, and with so many different sources of information on fat loss competing against each other for your attention, the internet can sometimes feel like a pretty dizzying place in which to search for any helpful information. Can you actually target belly fat when losing weight? So how can I lose fat quickly? Are there any disadvantages to trying to lose fat too quickly? It might sound obvious, but if your goal is to have a smaller belly, the best way to measure your progress towards that is just to measure your belly – once above the belly button and once below, every four to six weeks.