Can fasting or not eating on time cause gastritis?

Yes: Your stomach continues receiving gastric acid whether you eat or not. Food intake helps buffer against that acidity, so if you don't eat, the gastric acid will irritate your stomach and cause inflammation, what is known as gastritis. Anything that increases this acidity, I.e, medications, anxiety, alcohol, etc worsens the inflammation. Not eating on time can aggravate temporary.