I don't think she's depressed-instead, she's desperate. Desperate for love and acceptance and attachment-things she didn't get as a child.
She's trapped in a horrible body and as much as she says she knows how to lose weight, she won't do what's necessary. She eats to make herself feel better for the few minutes her stomach is full, she shops to make herself feel better until the trinkets get boring shortly after, and she makes videos to get asspats for nothing.
But she feels unsatisfied. In her mind, she's screaming into the void and she thinks nobody hears her. "Like a monster truck in the nightlife. " lol.
She doesn't understand that we do hear her. We can smell the desperation on her-for love, acceptance, admiration. But she won't do the one thing that would really start to earn it-and that's lose weight. That's the thing we see and the thing that is the most dangerous and troublesome. We know when she loses it she'll be getting better in other ways too.
Losing 350 pounds is hard and admirable and nobody can say otherwise. Getting the weight off would be the first step she needs to understand how her childhood affected her, but she likely needs therapy to do it.
But right now it's too hard, so she does all this other unsatisfying crap. She calls it depression but I think it's just being desperate to be what you aren't. Ultimately, nothing she does will bring her peace until she loses the weight and understands why she put it on in the first place.