Hi Candi, Kathryn Dewey PhD recently presented on Impact of BF on Maternal Nutritional Status at the Academy of Breastfeeding Medicine. Her take home message was that studies that defined breastfeeding well and actually measured postpartum weight loss (rather than estimated it) found an effect of breastfeeding on postpartum weight loss. Here are my notes from that portion of her presentation: Post partum weight change. Estimated energy in milk secreted + cost of secreting milk = 645 kcal per day 117,390 kical over 6 months Little evidence of energy sparing adaptations (possibly decrease in physical activity) If energy intake not increased, and all energy costs met by fat mobilization, would require 13 kg of fat. This doesn’t usually happen, so something else must be going on. Mostly women eat more, because they are hungrier. Lipoprotein lipase decreases and lipid mobilization increases in femoral region, so fat moves upward in the body, off the hips onto the arms and upper body. Prolactin assiciated with appetite and food intake in rodents. Prolactin receptors are upregulated during lactation, so this probably plays a long term role in appetite and weight regulation during lactation. Methodological challenges of evaluating the effect of bf on postpartum weight change -not possible to randomly assign women to bf or not Potential confounders Age, ethnicity, education, income Pre pregnancy BMI (gain less in preg, lose less with higher BMI) Parity, interbirth interval Physical activity and dietary practices are critical, especially the intentional restriction of dietary intake. Once believed one can’t diet during lactation, however women who are overweight can lose 1-2 lbs per week and not jeopardize lactation. Restriction of 500 kcal a day below energy needs is safe. No studies assessed for mother’s beliefs about safety of dieting on bf. Timing of first postpartum assessment and duration of follow-up. Best time to do baseline is a few weeks after birth, when the extra fluid is no longer on board. Many studies used moms prepregnancy or early pregnancy weight or an estimate based on the moms self reported weight, some subtracted the infant weight of the pregnancy weight gain Weight retention can be done if it controls for pregnancy weight gain. defining bf Ever or not Duration, exclusivity Lactation score that combined duration and exclusivity. Hondoras studies Excl bf for 4 or 6 mos. When solids were initiated, the babies took less breast milk, isocalorically. Study 1 primips- mothers identical in weight avg at 4 mos, at 6 mos the excl bf group made 100 ml more milk and lost significantly more weight .7kg in those 2 mos, the solids feeding moms lost none. Study 2 LBW infants Less of a difference of milk output, and the moms that fed solids early just lost slightly less weight than the moms who exclusively breastfed. Studies with measured postpartum weight change: 7 total , sample sizes vary greatly, all but one done in industrialized countries Most had info on exclusivity Some did body composition date All studies showed that breastfeeding caused more weight loss except the one that was done in Australia with any breastfeeding as a definition. Of the studies that only estimated weight loss, only one found a relationship. Poor quality studies did not show the weight loss increase, but the well done studies did. Am J Clin Nutr 1993, 58 162-6 - Dewey, Nommsen, et al - matched by weight , bf moms lost more fat. Janney found dose response relationship between weight loss and breastfeeding. McKeown & Record J endocrinology - breastfeeding moms who continued to bf continued to lose weight. 2-3 lb difference between the early mid late weaning groups by 12 months. Ohlin Int J obesity 1990 Weight loss was significantly different during early lactation. Magnitude of difference in maternal weight loss, of .6-2 kg over 12 months. Micronutrient status - nutrient needs are substantial for certain nutrients. Little research on the effects of lactation on maternal micronutrient status. Extended lactation may be protective agains tmaternal iron deficiency. Developing countries - problems getting enough vitamin A and B6 Greatest weight loss was at 3-6 months postpartum. Kathryns theory is that women are very hungry when prolactin levels are high initially, and they eat to hunger. She thinks that when prolactin levels drop, the mom is not as hungry, but she is making as much milk, so she loses weight. After 6 mos, solids start to reduce milk intake, so mom loses less weight. Role of breastfeeding is small compared to preg weight gain, dietary practices, and physical activity. Some women lose weight after weaning, they may have really high prolactin levels, found on average there was no rebound effect after weaning, and there was little continued weight loss after weaning, with individual exceptions. Greater materna weight loss: advantage or disadvantage? In the US it is an advantage, in developing countries it could be a disadvantage, some moms are worried about excessive weight loss so they wean. Giving these moms more food will help them continue to bf. Breastfed infants who don’t need iron and get it have reduced growth and more illness. Some anemia seen in women is not due to iron deficiency, can be malaria or other chronic diseases. Don’t know consequences of excessive weight loss in women who are thin. *********************************************** To temporarily stop your subscription: set lactnet nomail To start it again: set lactnet mail (or digest) To unsubscribe: unsubscribe lactnet All commands go to [log in to unmask] The LACTNET mailing list is powered by L-Soft's renowned LISTSERV(R) list management software together with L-Soft's LSMTP(TM) mailer for lightning fast mail delivery. For more information, go to: http://www.lsoft.com/LISTSERV-powered.html