I'm eating a lot, but i've been losing weight very easily. i've lost 5 pounds since sunday, and it's now wednesday. i feel very lethargic. ?

See a doctor: Weight loss despite increased eating can be a sign of serious illness. Please see a doctor right away.

Seek an evaluation: While I can't be certain, I would have some concern for diabetes, as it's not uncommon for new persons with diagnoses of diabetes to present with increased eating but weight loss. I would strongly suggest that you see your doctor.

Ideal weight loss: Ideal weight loss is 1 pound a week. Time to stop "eating a lot"