You become constipated because the surge of GLP-1 slows down your gut and its emptying. The food and waste sit inside you longer and find it harder to get out. Similarly, you burp because “the valve that sits at the bottom of the stomach doesn’t open as quickly. The air must go somewhere, so instead of it going down into the small intestine, people start burping.” You become nauseous because the drug creates a sensation of extreme satiety—that you are full and can’t eat any more. The human brain struggles to distinguish between extreme satiety and sickness: the two signals get easily mixed up,
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