I don’t recommend any one eating plan for clients. I believe there is no “one fits all” plan. The plan has to work for the individual client, their needs, goals, desires, tastes, background, lifestyle, etc. I always recommend cutting out sugar, processed foods and additives/preservatives.
I think nutrition, after you get past calories in/calories out, is a conversation that needs to be had with each client. Portions is a big part of it. Portions have double in the US. We eat more and more of it is nutritionally void. Then its not so much about eliminating food groups, but about what the client can achieve. Changing a family favorite fried dish to baked. Swapping canned fruits and veggies with frozen or fresh. Some clients need to start slowly, other are ready to jump right in with a complete overhaul.
I treat nutrition like I treat training, its based on the individual, their needs and our discussions.