Just my personal experience. When I had my first baby I went back to work at 7 weeksPP. A colleague of mine had a baby a few weeks before me. we worked 12 hour night shifts together. We took turns during the night with the breast pump. We were both ravenous, always checking out the other nursing units in the middle of the night searching for food because we had already eaten everything we brought with us. i was down to my prepregnancy weith 4 weeks PP. i gained 28 lbs during pregnancy. One of the reasons I kept breastfeeding was because it was the only time I could eat as much as I wanted and not have to worry about weight gain. i didn't lose the weight as quickly the second time around but still had a large appetite and lost some weight and never gained while nursing.. my colleague alos lost her weight quickly. i have had friends who didn't lose much weight until they weaned...Must be individual differences.