alli works best with a low fat diet, which means between 12 and 19 grams of fat per meal. Fatty meals (fried foods, high fat dairy products, or any high fat products) will placed you WAY over the recommended fat limit and will contribute to weight gain and possible treatment effects as alli only blocks 25% of any fat you consume. I will strongly recommend consuming a low fat diet, which is not hard to achieve since almost everything has some kind of fat and calories.
If you consume fatty foods (fries, large sandwiches with fatty meats, big burgers with sauce, etc.) they usually contain about 84 grams of fat and over 600 calories per 1 serving. That is why alli encourages consumers to incorporate healthy low fats into the meal plan.
Hope this makes sense :)
Let me know if I can be of any help,
Sylvia Melendez-Klinger, MS, RD, LDN, CPT - registered dietitian