No, it's not. As we age, it becomes harder to keep weight off if we don't change our diets to reflect any infirmities we might develop that limit our activities. We don't burn off food the way we did when we were young. Our hormones change. We have to change throughout life to reflect our changing lives. So either you haven't done that, or you're diet has always been bad and it's now catching up to you, or you've stopped exercising, or the medication you're on or some other med is causing it -- lots of meds cause weight gain. Endocrinologists are notorious for telling patients that thyroid problems don't cause weight gain, but anyone with the problem or, like me, is married to someone with that problem, knows that isn't true. It could be your thyroid medication isn't adjusted correctly. When your doctor sounds like a fool, consider him or her a fool and find another.