Weight Loss Medications Xenical Xenical (orlistat) is a weight loss medication that inhibits the absorption of fat in your body rather than suppressing your appetite. Xenical is useful for long term use and has been shown to be effective for 1-2 years. Dietary fats are inhibited from being absorbed by using Xenical and this allows about 30% of the fat eaten in a meal to pass through the digestive tract undigested. Xenical helps to reduce and maintain your weight, as well as to minimize any weight regain.