The hashtag was attached to a tweet this week about exercise and diet, the New York Daily News reported.
"Just killed back to back spin classes," she told her followers, with the tag #PopSingersDontEat. "Eating a salad and dreaming of a cheeseburger."
At the conference in Brentwood two months ago, Gaga told girls she nearly ruined her vocal cords with bulimia, a yo-yo pattern of out-of-control eating combined with aggressive exercise, vomiting and crash dieting. She said she felt under pressure to conform to ideal patterns.
"Weight is still a struggle. Every video I'm in, every magazine cover, they stretch you -- they make you perfect," she said. "It's not real life."
One fan disappointed by the recent tweet wrote, "What happened to 'I'm beautiful in my way coz God makes no mistakes?'"
The National Eating Disorders Association asked if the tweet came from the same person who said at the conference the "diet wars" should end.
But some suggested salads and spin classes are healthy and would be an excellent choice for the many in the United States who are obese.