Anxiety as a disorder is when you chronically think anxious thoughts. If you don't do that, you don't have an anxiety disorder. Physiological ailments caused by anxiety only exist if you actually suffer from chronic anxiety. Everyone gets nervous about things here and there, and sometimes life throws a lot of stress at us, but that's not a mental illness. Chronic anxiety is. It can manifest in many ways, such as OCD, PTSD, GAD, agoraphobia, etc. All are defined by life being greatly and adversely affected by a self-defeating way of thinking that makes life harder and smaller. You don't say if you think like this. GAD, what you said you were diagnosed with, would be a rare diagnosis for an 11 year old, as childhood fears are not usually the same as an adult anxiety disorder. But that doesn't mean it can't exist, just that at that age, we usually think of it differently. Googling symptoms is usually a sign of anxiety, as why would someone do that? It's certainly not enjoyable to see all the things can go wrong with one's health. If you just have an interest in health, Google isn't the most reliable source for accurate info. It's very hard on Google to tell where the reliable info is because Google is gamed so what you see isn't scholarly expertise most of the time but sites that advertise and are selling a service and game Google so they come up first. Some of this info is generally educational, but it's so general it's not that useful. Now, if you go in 100 pages, you will stumble on something that might go into detail. So either you're anxious and searching for things that are wrong with you or you have a genuine interest and would be better served in a good library. Gastritis isn't really a disease state. It's a symptom involving an inflamed gastric system. That's true of most of the things that end with itis. It isn't a diagnosis really. Basically, you're saying colloquially you get stomach aches sometimes either when you overdo things or eat the wrong things or worry too much, which is very common. Food poisoning is a disease state that would involve eating something that has bacteria in it that is toxic, and your body gets really really sick in order to evacuate it from your system. Most likely you're not actually getting that unless you regularly eat rotten food or infected food. Lots of people with anxiety do have digestive problems. It's a common symptom. Lots of people under stress or who are nervous also get stomach problems. Again, common. 18 isn't a grown man. Whether humans ever grow up is in question, but 18 is still very young. It is, however, an age where those of us who are destined to get depression or an anxiety disorder usually start getting it, between 18 and until we reach our 30s. When you are a grown man you'll see the difference, again assuming anyone ever becomes one. I'm sure you've seen some pretty old men in the news the last few years who act like toddlers, so experience tells us humans really don't grow up or mature, they just get old. Can anxiety blow ailments our of proportion? What's proportionate when it comes to an ailment? Does for some, doesn't for others. It would depend on whether something physiological is wrong with you, and weight loss for no reason is an example of something being wrong, or whether you've seen docs and gotten the most thorough exams possible and everything has been ruled out. Only at that point can we say it's anxiety, but again, only if you chronically are thinking anxious thoughts. If you are, you need a therapist, but given what you've said here, I'd see a doctor first.