Since you are obese and on weight loss regimen. Sometimes this can result in acid reflux causing upper abdominal and chest discomfort (at times it can be burning sensation). As of now, nothing to worry about. Observe it for about 5 days
Next Steps
If it persists, it would be better to have one on one consultation with a physician.
Health Tips
Avoid starving for longer duration. Eat little and frequent meals (about 5-6 meals a day) . Avoid eating spicy food. Eat more amount of fruits and drink at least 4 liters of water in a day.