This means the experienced and loyal crew lose money, and miss out on layovers in exotic foreign destinations.
Magurina told the Russian service of RFE/RL that she had been flying for 15 years and was a senior cabin crew member on international flights.
But in August she was reassigned to internal routes because she was not thin enough under new rules.
"We were all photographed en masse and measured - some were even weighed,' she revealed.
"This was done under the pretext of company rebranding and ordering new uniforms for staff."
She stated: "My life changed in the middle of August."
Others had suffered before that, she said. Some 400 flight attendants have been hit by the new rulings.
"They stopped putting anyone on international flights if they are older than 40 or take more than a (Russian) size 48 (NZ 16)," said Magurina.
Not only is she forced to fly domestic routes to destinations in such places as Siberia, but these are often night flights, or early morning departures, which means she and others cannot sleep properly before going to work.
"When I asked what's going on, they told me these are the new rules of the game and that I was removed from international flights because of my clothes size - it mustn't be more than a 46, and I'm a 48," she said.
Igor Deldyuzhov, the president of a trade union representing flight crew, said there were many complaints of discrimination over age and appearance.
But staff were scared to go to court because they have children and mortgages and fear losing their jobs.
Flight attendants are desperately trying to lose weight in order to keep their international flight work, and the higher salary that goes with it, said Natalia, 42.
"Stewardesses were fainting from hunger at the controller's office as they tried to meet the new criteria," she said.
"But even if they managed to lose the weight they were told, 'You still wouldn't get to fly to the United States or Dominican Republic because you're a little old.'"
She asked: "Do you know how humiliating it is when they weigh you like some kind of cow?"
Aeroflot declined to comment on the claims. A recent report stated that one per cent of its pilots are women.