I actually shut down an adipose atrocity earlier, when they claimed that there was 'no scientific way' they could lose weight with that exact argument: "You, me, and everyone else in the world is made of matter. This means we all abide by the laws of thermodynamics, more specifically the conservation of energy: 'energy is never created or destroyed, only transformed.' Combine this with the first law of Newtonian physics (an object at rest tends to stay at rest unless exerted upon by an outside force) and you come to understand that activity requires energy. This means that if you take in less energy than you exert, your mass ~must~ decrease. It doesn't matter what your metabolic rate is, what endocrine conditions you have, or your state of mind: if you output more than you input, you decrease in mass. Period." I was being as kind as possible, as this person has friends who are influential in my life, but I couldn't tolerate yet another fat fuck trying to give reality the finger and trying to use bad science to do it.