Is "The waist measuring" wrong?

Hello, Here is a high school mid-term test question.

Fill in the blank with two words.

Simply measuring your waist is probably useful. A number of studies have shown that this number helps measure the chances of developing chronic disease. It's also easy to do.
The __________________ can be helpful because many people find themselves changing their muscle to fat as they go through midlife. Even though weight may remain stable, an expanding waistline can be a warning sign of trouble on the horizon. So use your waist as a kind of measuring device. A waist-wise expansion of two or three inches over the years would mean that you should reevaluate your diet and physical activity level.

The exact answer is "waist measurement."
But some students wrote "waist measuring."
I think both of them are correct, but the teachers say no to the second answer. Is there any big difference between the two answers grammatically or semantically within the paragraph?

Thanks.