answer:I can’t answer the first part of the question, but I can answer the second part. If you’re eating fattening foods, then not eating for an entire day, you’re going to gain more weight than you would if you ate something fattening, and then ate something else along with it. When you stop eating, even if it’s only for a day, your body stores the food it does get, instead of burning off the excess like it normally would. So, when you eat something fattening, it’s going to be even more pronounced and your body will save it all for the energy needed to go about your day. In order for your metabolism to work, it has to have fuel (food). With no fuel, it saves the energy (fat) as a standby fuel source. You can see the kind of cycle this will lead up to.