https://kcampbellnutrition.com/can-you-eat-before-a-stress-test/
The instructions about bringing a meal, or fasting for at least 12 hours prior to a nuclear stress test, depends on the reason for the test and the type of imaging that is needed. For some, the ingestion of a meal helps the body to want to concentrate blood more around the gut and intestines. This, in turn, puts a mild deprivation strain on the heart which is part of what we want to see: how will the heart behave under duress. The fatty component is not needed for any type of imaging, but it will help the meal to last longer in the stomach since fatty meals take longer to digest. If the imaging staff are called on for an emergency case, you are left halfway through your own diagnostic imaging while they deal with the emergency case(s). With an ingested fatty meal, you can wait for a while longer.