Effects of Energy Restriction and Exercise on Bone Mineral Density during Lactation

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Cheryl A. Lovelady, Professor (Creator)
Laurie Wideman, Associate Professor (Creator)
Institution
The University of North Carolina at Greensboro (UNCG )
Web Site: http://library.uncg.edu/

Abstract: Modest energy restriction combined with resistance training (RT) has been shown in nonlactating women to protect bone during periods of weight loss. However, there is a paucity of research on dietary interventions and exercise in lactating women aimed at promoting bone health and weight loss.Purpose: This study aimed to investigate the effects of energy restriction and exercise on bone mineral density (BMD) and hormones during lactation.Methods: At 4 wk postpartum, participants were randomized to either a 16-wk intervention (diet restricted by 500 kcal and RT 3 d·wk-1) group (IG = 14) or minimal care group (CG = 13). Measurements included BMD by DXA, three 24-h dietary recalls, and hormones. Repeated-measures ANOVA was used to test for group differences over time.Results: Energy intake decreased more in IG (613 ± 521 kcal) than CG (171 ± 435 kcal) (P = 0.03). IG lost more weight (5.8 ± 3.5 kg vs CG = 1.6 ± 5.4 kg, P = 0.02). BMD decreased over time, P < 0.01, with no group differences in lumbar spine (IG = 3.4% ± 2.5%, CG = 3.7% ± 3.3%) or hip (IG and CG = 3.1 ± 1.8%). Prolactin and estradiol decreased over time in both groups, P < 0.01. Basal growth hormone remained stable; however, there was a significant increase in growth hormone response to exercise in IG.Conclusions: These results suggest that moderate energy restriction combined with RT promotes weight loss with no adverse effects on BMD during lactation.

Additional Information

Publication
Medicine & Science in Sports & Exercise 44(8): 1570-1579
Language: English
Date: 2012
Keywords
Diet, Breast-feeding, Postpartum weight loss, Physical activity

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