I lost 65 lbs once, by just, completely cutting fat and red meat from my diet and, I was active.

Since I added a bit of fat and chocolate chip cookies back in and become less active, I gained back 35, but have held that for the last 3 years, by cutting down a bit.

A change in diet, activety, stress and/or attitude, can do it, but, You should still get a check-up, to make sure.