Every little bit counts
High end bicycle equipment has weight specs in grams.
It’s always hillarious to me to see boomers on expensive bikes that aim to save every gram while they could save 20kg on themselves.
If you are trying to lose weight, you should be using the worst, heaviest bike possible.

Well, not if you still want to have some fun while doing so.

But I agree, that a regular bike should suffice and you don’t need to worry about optimizing gear weight if you’re not competing for anything and just ride it for your own well-being.