On a ketogenic[diet] ... your body uses fat instead of carbohydrates for energy. This shift causes a major spike in ketones, the source of acetone breath. ... S

On a ketogenic[diet] ... your body uses fat instead of carbohydrates for energy. This shift causes a major spike in ketones, the source of acetone breath. ... Sweet-smelling breath may be a short-term side effect of this type of diet.[0] [0] https://www.webmd.com/diabetes/acetone-breath-diabetes https://www.webmd.com/diabetes/acetone-breath-diabetes So low blood sugar causes sweet breath.