Does that FDA weight loss pill Alli or whatever really work?

my neighbor whom i havent seen in a long time had lost 30 lbs she claims in a few months, not changing her diet,being equal with the food pyramid,and she just works as a busy mother/kinder garden teacher. So while following those directions with the pills she said she didnt change a thing,should i believe her,she does look a bit slimmer than before,which was a year ago. I’ve done some research but still can’t find a truthful answer.