Here's my oops story... Consider it a cautionary tale. But also take heart. It wasn't that big a deal. And it only happened once. (I've even talked about it on CNBC.)
Treatment effects are common if you eat meals with too much fat. They aren't a safety concern - they won't hurt you. But they could be embarrassing if you aren't prepared to deal with them.
The rule of thumb is to limit your calories from fat to about 30% per meal, or about 15 grams of fat per meal.
I learned this the hard way when I ate a fish sandwich and french fries from a fast food drive-through WITH TARTAR SAUCE, and a soda. Really smart, huh?
Good thing I was close to home so I could change my clothes.* But you know what? It hasn't happened since.
Yes, I still see occasionally undigested fat floating in the toilet. But I'd rather have the fat flushed away when I go to the bathroom than have it wrap around my waist or clog my arteries.
Studies show that about one out of every two alli users in a real world setting (real world, meaning you're on your own, versus being part of a "controlled clinical trial" where you get lots of instruction and advice) don't even get treatment effects. Those that do should expect to experience a "signal" that alli is working to block excess fat- but very few people (something like 5%) stop using the program because of how the product works.
Over time (I've lost 60 pounds and kept it off for about three years) I've learned to make changes in the way I eat. I still enjoy steak and potatoes - but I pick filet or strips versus rib eyes, and pass on the butter.
* My oops experience happened surprisingly quickly. That's not typical. The delay between eating a high fat meal and experiencing treatment effects varies from person to person but is generally 12 hours.