Here's a secret: people lie. Or at least embellish.
Fatties eat healthy in public to hide their shame and overly thin people eat, perhaps indulgently, in public to hide their shame.
That's why there's the myth of, "but I eat healthy, I don't understand why I'm fat!" and, "she's so thin, she can eat whatever she wants and doesn't gain a pound!"
No matter what you tell people, your body keeps an accurate record of what you have and haven't been putting in your body.