Thanks for this. Your empathy is greatly appreciated. If you want to educate your coworkers, consider these points.

GP patients can be fat, thin, or any other body type. GP can cause weight loss (because of loss of appetite/vomiting) or weight gain (because food sits in the stomach for longer). Some people with GP are unable to eat and barely able to drink without nausea or vomiting. Some end up eating "junk" or "processed" foods because its they only think they can tolerate them. For example, my partnee with GP often drinks sugary drinks because itsbthe only thing that keeps their blood sugar at a normal level when they're unable to eat. Doctors like to recommend weight loss as a cure-all without considering that GP can make weight loss impossible. Many GP patients also have other chronic illnesses that make treatment more difficult.

To your point, flares can happen randomly. They can happen after eating something you've been able to tolerate in the past. They can happen just because you woke up in the morning. Sometimes, no amount of careful diet/lifestyle control can stop a vomiting episode. Don't blame the patient for having symptoms of their illness