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ARS Home » Plains Area » Houston, Texas » Children's Nutrition Research Center » Research » Publications at this Location » Publication #78781
Title: LEAN BODY MASS OF WOMEN IS PRESERVED DURING LACTATION

Author
item Motil, Kathleen
item SHENG, HWAI-PING - BAYLOR COLL OF MEDICINE
item KERTZ, BARBARA - BAYLOR COLL OF MEDICINE
item MONTANDON, CORINNE - BAYLOR COLL OF MEDICINE
item Ellis, Kenneth

Submitted to: The American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/16/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: We wanted to find out whether lactating women experienced any change in lean body mass during lactation specifically, whether they lost lean body mass to support milk production. We examined the body composition of 10 lactating women, 10 nonlactating women and 10 women who had not ever given birth, over the first year after the first two groups gave birth. We calculated lean body mass from total body potassium, which we measured based on the body's natural gamma signals recorded by detectors placed above and below the subject's body. We determined food intake at 6-week intervals and kept track of protein, carbohydrate, fat and energy intake. The results showed that this group of breastfeeding women not only preserved their lean body mass for the first 6 months after giving birth, but they were eating 55 percent more protein than their nonlactating counterparts. Their high-protein intakes continued even though their milk and milk protein production declined. The fact that these women preserved their lean body mass throughout lactation suggests that the metabolic needs of milk protein production can be met solely by the mother's diet, not taken away from her own body's needs.

Technical Abstract: To determine if the lean body mass of well-nourished women was mobilized to support milk protein output during lactation, body composition was examined longitudinally at 6-wk intervals between 6 and 24 wk postpartum and at 52 wk postpartum in 10 lactating, 10 nonlactating, and 10 nulliparous women using whole body potassium (40K) counting. Milk production was determined at 6-wk intervals during the period of exclusive breastfeeding (6 to 24 wk postpartum) by the test-weighing procedure. Milk composition was determined by chemical analysis. Dietary intakes were determined at 6-wk intervals between 6 and 24 wk postpartum from 3-d food records using a nutrient database. Lean body mass was maintained in women who exclusively breast-fed their infants during the first 6 mo postpartum, while consuming dietary protein in amounts that exceeded those of their lactating counterparts by 55%. The high protein intakes were sustained throughout lactation despite a progressive reduction by 32% of milk protein output. Lean body mass was preserved throughout lactation in well-nourished lactating women, suggesting that the metabolic needs of milk protein production were met solely by the high-protein maternal diet.