Body Composition is different from weight loss. Weight loss is Calories In v Calories Out. Too complex for me to really target composition - I just try to look after my diet and be consistent with my training and, as Amber says regularly on the podcast, let the body do it’s stuff.
Regarding supplements - well I do use multi vitamins, and vitamin C, even though I know there’s no real scientific support. And I’d be confident I have a rounded enough diet in reality. However, I kinda go with it does no harm.
I also use whey, but I really don’t get why people see it as not real food. It’s in milk, and is a by product of making cheese. Processed maybe, and depending on the brand, some flavourings and sweeteners (and again despite the press, no proven evidence of them being harmful or negative response in humans).
fwiw, I supplement with whey, but rarely have a shake. I have it in my morning porridge and mixed with yogurt over a fruit/ berry salad, or as part of “overnight” oats (which I normally have in an evening to top up for morning workouts). I am partial to protein bars after my evening meal, which I can’t stand over as much, but I get ones that have reasonable quality protein!
Personally, given my age and training regime, I’d rather overshoot the endurance athlete recommendations. Again, nothing to back that up scientifically, just another “what harm”…