If you want to understand how the bulletproof coffee works, you have to go to the bulletproof executive's website and look it up. He basically invented it based on the butter tea they have in Tibet. But he hacked it as part of his bulletproof body hacking stuff.
Basically fat doesn't raise your blood sugar or your blood insulin, so it can help prolong some of the other things your body does in a fasted state without you having to actually be in a fasted state. However, if you are trying to lose weight, you do have to have a fat deficit. Your body needs to burn something for energy and if fat is all it has, it will use up the fat in your food first before going for the fat in your thighs. So unless you have a blazing fast metabolism, you can easily out-pace your body's needs with added fat.
Female, 5'3", 49, Starting weight: 163lbs. Current weight: 135 (more or less).
Starting squat: 45lbs. Highest squat: 167.5 x 2. Current Deadlift: 195 x 3