Losing fat is big business - it's something a great number of us aspire to do quickly, easily and healthily. But have you ever actually thought about where that mass actually goes?
After all, it can't just vanish into thin - pardon the pun - air.
Luckily, a video is at hand to answer a few questions about slimming down.
It explains that fat doesn't turn into muscle, like some theories go. It doesn't really turn into energy and it isn't really "burnt" off.
In fact, fat is broken down into water and carbon dioxide. The former escapes through our exhalation, and the water comes out of us via urine, tears and sweat.
According to the British Medical Journal, there’s a “surprising ignorance and confusion about the metabolic process of weight loss” among the public.
It explains that losing weight requires unlocking the carbon stored in fat cells.
Here's the video, which has been viewed a whopping 11 million times.