Is it hard to lose baby fat?

Can be. I read a statistic once that said most women never lose their pregnancy weight. It takes discipline. You must eat most fruits, vegetables and unprocessed foods. You must exercise everyday.
Breastfeed & lose wt. "dieting" is not needed, as long as the breastfeeding woman eats only as many calories as needed to maintain her normal (pre-pregnant) weight. For example, if she was 120 pounds before pregnancy and is now 145 pounds, she should eat just enough for a 120 lb woman. Her 25 lb excess will be gradually used up in the production of breastmilk (25 ounces of breastmilk contains about 500 calories).