Original Research Article No Changes in Weight and Body Fat in Lactating Adolescent and Adult Women from Mexico GRACIELA CAIRE-JUVERA, 1 * ESTHER CASANUEVA, 2y ADRIANA VERO ´ NICA BOLAN ˜ OS-VILLAR, 1 LUZ MARI ´ A DE REGIL, 3 AND ANA MARI ´ A CALDERO ´ N DE LA BARCA 1 1 Centro de Investigacio ´n en Alimentacio ´n y Desarrollo, A. C. Hermosillo, Sonora, Me ´xico 2 Instituto Nacional de Perinatologı´a, Ciudad de Me ´xico, Me ´xico 3 Universidad Iberoamericana, Ciudad de Me ´xico, Me ´xico Objective: To evaluate changes in weight and body fat of Mexican adolescent compared to those of adult lactating women from the Northwest (NM) and Central (CM) regions of Mexico in the first trimester postpartum. Methods: A prospective design was used to evaluate 41 exclusively breastfeeding women (21 adolescents and 20 adults) recruited 1–2 days after delivering a healthy singleton at the Hospital Infantil del Estado de Sonora (Northwest Mexico) and Instituto Nacional de Perinatologı ´a, in Mexico City. Socioeconomic status, height, body weight and compo- sition, dietary intake, physical activity, and milk volume (quantified by deuterium dilution method) were measured at the 1st and 3rd month postpartum. Results: Women did not lose weight throughout the first trimester postpartum. Mean postpartum weight retention at the end of the study was 3.8 kg. No differences in weight and body mass index (BMI) were found between adolescent and adult women in both periods. Energy and macronutrient intakes, physical activity and milk volume were similar between the two groups of women. In both periods, adolescents from the CM region had lower weight, BMI, and body fat than adolescents from the NM region (P<0.05). At the 3rd month, pregestational weight (P < 0.0001) was a predictor of BMI, and region (P < 0.05) and milk volume (P < 0.01) were associated with percentage of body fat. Conclusions: Exclusively breastfeeding for 3 months did not reduce weight or body fat in the Mexican population of this study. Efforts to avoid weight retention in the lactation period may contribute to prevent overweight and obesity in women. Am. J. Hum. Biol. 24:425–431, 2012. ' 2012 Wiley Periodicals, Inc. Lactation is a physiological state that may have differ- ent effects on maternal nutritional status, depending on its duration and intensity (Butte and Hopkinson, 1998). In the last decades, several studies have assessed the energetic impact of lactation by measuring anthropomet- ric changes in breastfeeding women under different cir- cumstances. Some of the previous studies on the effects of breastfeeding on maternal weight showed that lactation significantly reduces weight (Dewey et al., 1993, 2001; Janney et al., 1997; Kramer et al., 1993; Motil et al., 1998; Piperata and Dufour, 2007; Vinoy et al., 2000) and others did not find an association (Boardley et al., 1995; Brewer et al., 1989; Butte et al., 1997; Dugdale and Eaton-Evans, 1989; O ¨ hlin and Ro ¨ssner, 1990; Parker and Abrams, 1993; Petrucci et al., 2001; Schauberger et al., 1992; Valeggia and Ellison, 2003; van Raaij et al., 1991; Walker and Freenland-Graves, 1998). This heterogeneity of results can be partially explained by differences in the research methods used. The variability shown in different studies can also be explained as reflecting changes in maternal energy availability and the individual physiological strat- egies used to meet the metabolic demands of lactation (Dewey, 1997). Therefore, changes in maternal weight and fat mass (FM) in response to the metabolic load imposed by lactation are highly variable among and within diverse human populations (Butte and Hopkinson, 1998). The effects of breastfeeding on maternal health will be differ- ent in different cultural contexts or at different levels of development (Rasmussen and McGuire, 1996). Over the last years, concern about the growing epidemic of obesity in developed countries has directed increased attention to whether lactation can contribute to reducing the large amount of body fat deposited during pregnancy by well-nourished or over nourished women (Lederman, 2004). Obesity is an important health problem because of the number of people affected and the associated comorbid illness and premature death (Misra et al., 2010; Rasmus- sen et al., 2010). The prevalence of overweight and obesity has increased worldwide as a result of the rapid nutritional transition observed in many countries (Astrup et al., 2008). Among adolescents, increased weight has been docu- mented, and data from developed countries suggest that the diet of adolescents may increase the risk of developing chronic diseases, such as cardiovascular events, diabetes, cancer, and osteoporosis (Lytle, 2002; Schneider, 2000). Young adulthood seems to be a time of heightened vulner- ability for excessive weight gain in women (Goldschmidt et al., 2008), suggesting that there may be factors operat- ing during late adolescence and early adulthood that pre- dispose to obesity. Childbearing has been identified as one such factor (Gunderson et al., 2004), as it is a period char- acterized by profound changes in weight. Some studies have mentioned that lactation may impair the nutritional status of adolescent mothers, due to the elevated energy requirements needed for their own Contract grant sponsor: International Atomic Energy Agency; Contract grant number: 9381. *Correspondence to: Graciela Caire-Juvera, Coordinacio ´n de Nutricio ´n, Departamento de Nutricio ´n Pu ´ blica y Salud, Carretera a la Victoria km 0.6 P.O. Box 1735, Hermosillo, Sonora, Me ´ xico, CP 83000. E-mail: gcaire@ciad.mx y Deceased. Received 1 September 2011; Revision received 25 November 2011; Accepted 17 December 2011 DOI 10.1002/ajhb.22234 Published online 18 February 2012 in Wiley Online Library (wileyonlinelibrary. com). AMERICAN JOURNAL OF HUMAN BIOLOGY 24:425–431 (2012) V V C 2012 Wiley Periodicals, Inc.