Yes, this has been known for a long time, though it's not stressed as much as perhps it ought it to be.

It's not clearcut either, though it surely has that effect on many. When I went on the KETO diet even though it led me to eat hard cheeses and red meat for almost the first time in my adult life (and rather a lot - I just had to find SOMETHING to please my taste buds, having had to eliminate so much), my lipid profile vastly improved including lowering my LDL.

It seems weight loss figures heavily in my lipid profile. If only I could keep it at the level that seems most effective!

Everyone is different in how various food stuffs effect our health. One major factor seems to be our gut biomes and others just aren't understood - like how we metabolize things.

One ongoing study (I wish I could find it) involves carefully following the diet components of a large group of people - pretty much everything was tracked and so were health changes (including, of course, weight).

One lucky group was found to lose weight eating chocolate!

One of my clorestorol numbers is off but I forgot which one the Dr. said and can't research now.

I need to think about it before deciding to take statins or not.

I'm generally leery of any diet that is all or nothing - KETO, Paleo, Adkins, etc., all fit into that category for me.

Was it Michael Pollan who advised something like "eat a lot of different things, mostly plants" or something similar?

I don't consider vegetarian as an all or nothing diet, fwiw. I do know that to be really healthy as a vegetarian you need to know what you're doing. There are a lot of unhealthy vegetarian diets.

Vegan - it's sliding over into the all or nothing category for me. YMMV!