Bullimics don't feel comfortable binging in front of people so it is usually done alone, or at odd times, such as the middle night. You may catch them purging at 3am or "showering" in the middle of the night. Check their car for food receipts, fast food bags, etc.
Beat bulimia using the 3 Techniques taught in my private online program and community
Just recently I emailed my friend and said "Funny (well, not really) how many psychologists, doctors, dieticians, support groups, hospitals, and even a hypnotist, I went to over the years that couldn’t help me – and all it took in the end was a simple site like this... - Cassie (Shared with permission)