This little video draws it’s inspiration from (supposed) Buddhist monk fasting breathing practices and a small study (60 subjects) https://journals.sagepub.com/doi/full/10.1177/2156587217707143.
The idea is to stretch the stomach to induce a feeling of fullness and so make it easier to delay eating.
I’ve done it once - did it work?
Maybe.
But, maybe it was the distraction of putting it on this forum…