My penis is shrink by 1 inch.i m slim . diet is good how can i regained the original size which was 6 inch. i do excercise daily. i measured if before also but now it is only 5 inch?

Measuring the size of penis is tricky, was it down or pulled straight, measured from the pubic bone or the pre-pubic fat, up to the tip of the glans or foreskin the temperature etc. If you are in good health and have normal erections chances of any pathologic cause are very small. I suggest you measure again using the same method each time and am confident you will find that the size i the same