The singer went up to 240 lbs when she was pregnant with her daughter, Birdie. She managed to get back to her pre-baby weight in six months thanks to some help from her trainer, Harley Pasternak. The star lost 100 lbs by changing her diet. Harley Pasternak, to 'Us Weekly' Harley Pasternak, to 'Us Weekly' Pasternak also revealed that Simpson follows the principles of his 2013 book, 'The Body Reset Diet.' She had three meals and two snacks a day with protein, fiber and healthy fat.