IME, clients do better when they have some control over the diet design. This reflects the dieting axiom, “The best diet is the one you stick to”.
So, keeping in mind that you absolutely must establish a chronic energy deficit (week in, week out), it’s largely up to your friend as to how to achieve that:
If she likes rich foods, maybe the low-carb (i.e. Atkins style) approach will work; if she prefers feeling full all the time, maybe the ‘volumetrics’ approach is better (i.e. lots of fibre to fill up ther stomach and gut), if she’s the fastidious type, then a simple ol’ fashioned calorie controlled diet may be the go…
It really is horses for courses…so long as you keep hitting that energy deficit !
Cheers
Mav