cambridge diet and doctors

Hi all just a quick question...
I did cambridge diet a couple of years ago i was 3 stone heavier than i am now.
I didnt need a dr's note to start, why is it that i do now?
Is is due to ur BMI, at what point is it that you need a dr's note to start?

Thanks in advance

All people starting on CD are advised to see their GP. However, if your BMI is over 40, or you are on prescribed medication you need a GP signature to start.