Take this medication 'on an empty stomach'. [=when your stomach is empty because you have not eaten for a time]
When I had the flu, just the thought of eating made me 'sick to my stomach'. [='nauseous']
She felt a flutter in 'the pit of her stomach' when he walked through the door.
(..) -All right. -You didn't put dairy in this, did you? -No. -Because you know l'm lactose intolerant. Last time, l barely made it to the bathroom. Why would l want to disturb your stomach? There goes your girls. Come on, man. Let's do this. -Hi, l'm Kevin Copeland. This is-- -Wait. Hold on. (..)2004 White Chicks