Hello and thanks for submitting your question. While marijuana has been used to stimulate appetite in HIV
and cancer patients I do not recommend this if you are otherwise healthy.
The more important thing to consider is why you are not gaining weight. There can be a number of causes including depression
or thyroid dysfunction
I encourage you to discuss this with your physician who may consider ordering some simple blood tests to rule out an underlying disorder. If all of this is fine then you may consult a nutritionist who can counsel you on healthy calorie dense foods such as nuts, lean meats and the like.
Thank you again for your question and I wish you all the best and continued good health in the future.