I told my doctor exactly what I was doing and he watched the results over the following year and for that matter over the last 7 years, I dont suppose he entirely agreed with me to begin with but he didnt try to stop me, how could he?
I would never lie to my GP or any other HCP, why would I do that and possibly conpromise my own health, what if I became dangerously ill how could they possibly treat me correctly and diagnose any problems if they werent in possession of the full facts?
To my mind, anyone who doesnt tell their Doctor the whole truth and keep them in the picture is potentially making trouble for themselves, whats the worst that a doctor could do? Tell you that they didnt agree with you? Big deal. Tell them the truth, for the sake of your own future health.