Hydrochlorothiazide is a diuretic, also known as a water pill. These medications work by removing extra water and salt from your body. Because of this, temporary weight loss due to water loss while taking this medication is possible. However, you should not take hydrochlorothiazide for weight loss as it is not approved for this use. If you have questions about body weight and hydrochlorothiazide, it is best to speak with your provider or pharmacist.