Where does Schwarzbein say this? On p. 124, she has a heading, "You Can Overeat Carbohydrates, but You Cannot Overeat Proteins and Good Fats." She goes on to explain the biochemistry, summing up, "If you ignore the feeling [the nausea from eating too much fat/protein] and you keep eating, you will either become further nauseated or vomit."

Then on p. 251, she writes, "Eat fat with every meal. Listen to your body. It knows its fat-intake limits. Do not worry about fat grams; your body takes care of this through the feedback mechanism of satiety. If you eat too much fat, you will get stick to your stomach and possibly even vomit. You should eat as many healthy fats as you want, varying your selections."

Sheldon