The body has a very strong preference for burning fat rather than muscle. Breaking down muscle for energy is a last resort. The reason why conventional wisdom s

The body has a very strong preference for burning fat rather than muscle. Breaking down muscle for energy is a last resort. The reason why conventional wisdom says you can't lose fat without losing muscle is because most diets put the dieter into a larger calorie deficit than the body can support through burning stored body fat. The 0.9% number is very important here. Go over it, and yes, your body will try to find energy elsewhere which includes your muscles. That's why I said to start with a 50% margin of safety. Also it's important to keep in mind that the body isn't a set of binary switches. There are many feedback loops, buffers, and redundant systems beyond the simple model I presented, which is another reason to not go 100% on this. 50% though will help ration food out for a longer period of time without getting into a situation at the end of the crisis period with too large of a calorie deficit to function properly or to prevent muscle breakdown.