I don't disagree with what you've written, but regarding your brief point on exercise... On my journey to lose 100 pounds I came across a meta-analysis of studies on weight loss* which indicated that, while exercise wasn't a significant contributor to short-term weight loss, exercise was correlated to successful long-term weight loss (a much less likely occurrence, since the vast majority of people who lose weight regain it within a decade).

*I read this analysis a decade ago, so I can't really find it to share.