You've already gotten some great responses, but to reinforce the point: talk to your wife immediately.

I went from being a skinny kid to a chubby adolescent. I knew already that I wasn't as pretty as the other girls, but my mom made me EXTREMELY self-aware about the issue. Don't get me wrong, I love my mother and believe she genuinely thought that giving me that kind of criticism would push me into being healthy and active. But it honestly destroyed my self-esteem and made me hate my body. My mom's criticism had the opposite of its intended effect-- I started seeing food not as a part of daily life but as some weird demon. I ended up becoming severely underweight and hospitalized by the end of college, but I STILL had that awful voice in my head telling me to keep going, because I was worthless if I wasn't skinny.

I'm much healthier now, but I genuinely still deal with my eating disorder every day. Not throwing up meals is a conscious decision I have to make all the time. Forcing myself to eat dinner even though I didn't run 5 miles right beforehand is still a struggle. Being only two pounds medically underweight when I used to be 40 is hard. I know I'm better than my physical appearance alone and have a lot to offer, but that latent obsession is always there. It. Fucking. Sucks.

Your daughter is at an extremely vulnerable place in her life. The decisions you make now are so important. Please talk to your wife-- please consider the thought that your wife herself may have disordered thinking about her own body (turns out my mom did). You have this opportunity to help them both and, judging by the concern and love you clearly have for them, you will.

Best of luck, OP.