Given all this contradictory information, if you're someone with a BMI between 30 and 35 , and your doctor tells you that you need to lose weight in order to get IVF, you have every right to ask questions, Anderson-Bialis says. If a doctor gives you suggestions you're not comfortable with, or turns you away, ask them to explain the data that proves this is the right decision. "If the doctor can’t do that, but makes such concerted recommendations about weight loss, there's probably another host of things the doctor will do," he says. "That's a litmus test of how data-driven they are or whether they rely on their gut, outdated data, and lethargy."