"I smoke marijuana to stimulate my appetite, but my friend recently told me that it can actually have the opposite affect and suppress your appetite if you are smoking alot. I'm a 24 year old guy. Is this true?"
Yes, people do have paradoxical reactions to any medications. Loss of appetite is on the same line of complaints as binging from overstimulation of the appetite and in the middle is normal so anything along that line can give you the the symptoms you are experiencing. Higher THC tends to stimulate the appetite in some people but with long term use or frequent use, we often hear complaints of nausea and this would indicate the receptors are full and you may need to take a cannabis holiday since tolerance has developed. Smoking marijuana does tend to be the fastest way to stimulate the appetite but it must be done in small doses to achieve appetite stimulation successfully. I really don't like recommending cannabis for appetite stimulation since most Americans gain ten pounds per year and in five years that's 50 pounds. Guys really need to lift weights to bulk up and gain weight plus you'll love your body because it won't look like cottage cheese and it doesn't take much weightlifting since men have testosterone to help fill out the muscles.