Can a relatively skinny guy like me (9-12% body fat) lose fat while gaining muscle through fasting and eating healthy and weight lifting, or is it harder to do both at the same time if you're already pretty low-fat?
All of these thing dont work together,
Fast gove your less or no calories, weightlifting require huge amount of calories to lift, and you need protien to make muscles.
So fast will make you lose fat and then lose muscles, because muscles are also source of energy, your weightlifting will make you lose muscles.
Also eating healthy, what do you mean by that? Are you vegan? Thats what i hear mostly when people say eating healthy.
If you need muscles then eat meat, you need Protien to build muscles, also fat is good if you are weightlifting, because if you dont have fat then you will lose muscles as i said above.
So keep fat, eat meat, make muscles by weight lifting, once you have muscles then you could try to lose some fat, but not all. Fat is good.