Hi Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concern...
Masturbation frequency of 4-5 times a day is excessive & it would harm you. It could reduce your weight as well as height if continued for longer period, This is due to lot of energy is consumed in that. You could prevent that by having diet rich in nutrients such as
vitamins, minerals & rich in starch(cereals) as well as fats for energy production.
However excessive masturbation would not effect your penis size. Excessive masturbation could be harmful to your future sex life. Excessive masturbation can cause keratinization (hardening of mucosa) of
glans of penis. Which can cause penis insenstive to normal stimulation during sex. This may cause lack of pleasure during sex & inability to ejaculate during sex.
To reduce masturbation, You should try to focus more on your studies, sports activities,etc. Make new friends & spend time with your friends. You should also avoid watching porn/adult content. You could sleep in such a way (such as tight clothes, wearing gloves etc) that your hands could not gain access to your penis.
Hope this information helps
Good luck