Eating too much fat with alli is very likely to cause TE's. The alli diet is formulated on 30% total calories from fat, 20% protein and 50% carbohydrate. That's similar to the diet of the American Heart Association.
The claim that "alli helps people lose 50% more weight than just diet alone" is based on over 100 studies that used that formula, so other diets are hard to predict. But TE's are pretty reliable when too much fat is consumed.
I hope this helps. Please let me know if you need anything else.
Pat Baird, MA, RD, registered dietitian