Some women indeed do not lose weight when breasteeding, but a myth it is not! Lactating women need about 500-600 calories more per day for a total of 2300-2500 calories per day! So indeed, lactating is a calorie-burning activity! Those who do not lose weight either keep their calorie intake about where it should be or consume more calories than they need. I lost weight readily even though I was eating lots so I probably had an intake of about 2100 a day.