What a great question and one that is not often asked as far as I see. You are talking about cannabis that is bred with the cannabinoid THCV, or tetrahydrocannabivarin. It is psychoactive and has many medicinal qualities, but one of the side effects is that it is an appetite supressant! For this reason, certain people like those undergoing chemotherapy or who need to eat more would not want cannabis high in this cannabinoid.
Strains higher in THCV are stimulating and have an energetic effect. Strains high in THCV also been known to reduce anxiety, induce bone growth and help regulate blood sugar. Some popular strains that are high in THCV are Durban Poison, Willie Nelson, Girl Scout Cookies, & Tangie. Most often, these high THCV strains are of African origin and are usually sativas.
I am not a doctor and this represents my opinion and research only. I hope this helps!