Almost all of the moms I know have battled the baby fat syndrome. Losing those excess pounds after the baby was born is no easy feat. The human body goes into survival mode to produce milk for the newborn. The new mother's mind is geared to eat and eat more to produce that milk. It doesn't matter if the baby is bottle fed or not the body wants those extra calories.
The most experienced mother I can think of is Michelle Duggar, the mom who has given birth to 18 children and the 19th one is on it's way. She made a comment recently about how she was trying to lose weight between children and was having a hard time about it. She took a pregnancy test and found out she was pregnant yet again. Michelle is only 42 years old and I can think of better ways she can control her weight rather than being pregnant most of the time.
The Duggar family has stirred up a hornets nest on the internet with people both supporting her right to bear children and others who think she and her family are living off the American TV viewing public for their income. You can find out more about that gossip here.