I am not familiar with HC Protocal. You will have to give me more information so that I can better understand what you are taking and how it is affecting your body.
I suspect that your "rumbling" is the extra bile and enzymes that are discharging from the gall bladder. This can be a common symptom of a not eating any food when the body expects it. There is no food to digest so it just "rumbles" around.
Please get back to me with more on the product that you are taking so I can be more accurate.