Weight loss vs. Muscle Loss vs. Fat Loss

This is so difficult. It is so hard to remain on track but not see progress. Am I doing the right thing? Do I look better? etc, etc. 

On the other hand - sometimes I see super rapid weight loss, and I feel weaker too. And I wonder if that is muscle loss. 

Weight - the number on the scale

weight = fat + muscle + water

var(fat) is low
var(muscle) is low
var(water) is high

Muscle Mass

The critical thing is to just maintain and maybe increase this a bit. 

Fat Loss

The ONLY way this can happen is a calorie deficit, fat activation, NEAT, etc.