The crew were significantly overweight and had been given time to lose weight but had not, said Air India spokesman Jitender Bhargava. He declined to give details on their weight.
A lawyer for the women blasted the firing. "The action is illegal and against the natural justice. I will soon file an application in the Supreme Court against the order," Arvind Sharma told the Press Trust of India news agency.
Air India has spent years fighting for the right to fire cabin staff it considers physically unfit. In 2006, it warned its nearly 1,600 cabin crew workers to shape up in two months or risk being assigned to ground duties- jobs that often pay less than those in the cabin. When the airline reassigned employees it deemed overweight, some of them took it to court.
Last year an Indian court ruled in favor of the airline, paving the way for the firings earlier this week.
The airline said that fitness and efficiency were the reasons for its weight standards, which it said were based on "scientific" combinations of height, age and gender. It did not give further details about how such standards were determined.
While all the cabin crew fired this week were women, Bhargava said there was "no gender bias. The rules are the same for both men and women."
India has laws aimed to protect against discrimination based on factors including caste, gender and religion, but no specific ones about weight.
Air India has tried in the past few years to change a public perception of its cabin staff as tired, unfriendly and inefficient.
India's airline industry has grown dramatically in recent years as rising incomes and loosened regulations put air travel within the reach of millions of new customers - and increasing pressure on Air India to remain competitive.