Britney Spears has been warned to shape up fast or be dumped by husband Kevin Federline

Pop star Britney Spears has been warned to shape up fast or be dumped by husband Kevin Federline by a previous love of the

dancer, contactmusic.com reported. Spears has a fuller figure since giving birth to their child Sean Preston last year (05), but Federline''s ex girlfriend Felicia Cabiero insists he is so image-obsessed his eyes will wander unless the singer loses some weight.

Meanwhile, according to ananova.com, Spears who was once named the sexiest celebrity on the planet, does not even figure in this year's top 100 list. Spears had topped the FHM's sexiest woman poll in 2004 and made it to the sixth position in 2005.

But in the most recent poll she was placed 20 places outside the 100. As of now, Spears will need 20,000 more votes to enter in the top 100.