This is a very common problem and the solution to your problem is in your question itself.
If you won't have food at regular timings you are prone to have gastric problems. Now since you visit market very often as per your job demand and if you are not able to have regular meal timings pls follow these-
1- pls do not be empty stomach as it will aggravate your problem
2- keeps some nuts handy-almomds, raisins, walnuts that can be consumed any time
3- when ever you are in market n you feel hungry stop by any hawker n have 2 bananas or one orange or a bunch of grapes and have them
4- avoid roadside wada-pav etc this will aggravate your problem
5-have lots of water- coconut water but not packed fruit juices
Since you seem to be obese, staying empty stomach may lead to weight gain
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