Last year, Air India warned about 600 employees — about 17% of the airline's cabin crew — that they must lose weight or they would be reassigned to jobs on the ground.

India's Directorate General of Civil Aviation had issued guidelines on fitness and declared that female cabin crew with a BMI between 18 and 22 are "normal," between 22 and 27 are "overweight," and over 27 are "obese." Male cabin crew are considered "normal" if they have a BMI between 18 and 25. While the flight attendants' union questioned the authority of the DGCA over them, that hasn't stopped Air India from taking action on the guidelines.

Air India declared the 600 crew as "temporarily unfit" for flight duties, and ordered them to lose weight within six months.

“About 130 of them failed the reassessment,” an Air India official told The Telegraph. “We are now declaring them permanently unfit for their job as flight attendants.”

Crew declared permanently unfit will either be reassigned or "offered voluntary retirement," according to the Hindustan Times

"These employees have already availed 18 months time to meet the required BMI but failed to do so, leaving with us with no choice but to replace them," an airline spokesperson said.

The U.S. Department of Health and Human Services, however, calls a BMI between 18.5 and 24.9 "normal," between 25 and 29.9 "overweight," and over 30 obese. There is also significant debate about the value of using BMI, or "body mass index," to determine whether or not someone is overweight. The height-to-weight ratio does not take into account other health metrics.

But Air India says the BMI measurement implies fitness for the job of flight crew.

“People who are fitter can respond quicker and more efficiently in case of any untoward situation," an Air India official said.

The DGCA guidelines also include a requirement for regular medical examinations — every four years for crew under 40, every two years for those between 40 and 50, and every year for those over 50.

Air India did not immediately respond to a request for comment.