I'm not on the plan but I make myself a slimfast shake every day for breakfast. It's fast, convenient and keeps me full but not just by itself. This is my regular formula:
1 cup of slimfast chocolate royal poder
250 ml organic partially skimmed 2% milk
1/2 cup of mixed berries (raspberries, blackberries, strawberries and blueberries)
2 tbsp psyllum husk
So far, it's worked for me but I've never tried the full plan because it seems a little lacking.