My last employer had a fitness requirement for staff hiring and appraisals. The requirement being that the staffs maintain their BMI in the range of 18.5-24.9 , regardless of position served. Their reasoning being that staffs that maintain their BMI in the normal range would be healthy and be more productive. If the staff meets all other requirements, but fail in BMI (under or over), they are allowed 30 days to correct it. If they are still out of range after 30 days, even by half a point, they would fail the hiring/appraisal process.

Though it was a mandatory requirement, they never posted it on their job ads. This specific ad though, is weird. A person could meet that requirement and still be obese/underweight depending on how short/tall they are.