Is it permissible to use acupuncture needles – which are placed behind the ear and cause a decrease in appetite – for weight loss?

It is permissible to use injections that reduce appetite only if they have no side effects on health, as this is a means of reducing permissible food intake. Fulfilling all of one's desires is blameworthy and may lead to harm, as stated in the Hadith: "No human ever filled a vessel worse than the stomach. A few morsels are sufficient for the son of Adam to keep his back straight. But if he must eat, then let it be one-third for his food, one-third for his drink, and one-third for his breath."