Isn’t it amazing how celebs lose all that baby weight within weeks of giving birth? While some stars will cop to extreme exercising — Kate Hudson reportedly worked out three hours a day after giving birth to baby number one, and Halle Berry used the 321 Baby Bugle Be Gone method, which kept her in the gym at least an hour a day — a majority of other celebs claim otherwise.

Six weeks after giving birth to her son Benjamin, model Gisele was back to pre-baby shape, telling “Vogue” that she hadn’t exercised much and saying, “I think it was muscle memory.” (She also said that giving birth “didn’t hurt in the slightest.” Eye roll.)

So, what’s the real deal when it comes to losing that baby bump? According to Erika Schwartz, MD, an expert in hormone therapy, “Without complications during birth, if a woman follows a healthy diet, increases sleep to 8 hours a night, and gets exercise three to five times a week while breast feeding for an average of three months,” she says, “it takes about eight months to a year.”