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Weight Loss After Pregnancy
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Postpartum Weight Loss Many women are faced with the task of shedding excess weight after childbearing, and they often seek medical guidance for weight loss. Some were overweight prior to pregnancy, while others gained excessive weight while “eating for two.” Regardless of the specific nature of the weight gain, the weeks and months following delivery involve attempts at weight loss for most women. Questions often arise as to how to safely accomplish weight loss after pregnancy, and whether or not special considerations are indicated when a new mother is breast-feeding. It is widely thought that breast-feeding accelerates the process of weight loss after delivery. An informational pamphlet from La Leche League states that breast-feeding will help mothers lose the extra fat deposited during pregnancy as an energy reserve to support lactation, whereas mothers who bottle-feed must rely on diet and exercise to lose weight postpartum. However, a 2001 study of postpartum women in Montreal confirmed findings of prior studies that showed infant breast-feeding was not associated with statistically significant differences in the rate of weight loss during the first 9 postpartum months. The Montreal study highlighted several factors that did appear to be important predictors of postpartum weight loss. Women who gained more weight during pregnancy lost weight more quickly after delivery. Women who smoked postpartum lost weight more quickly than non-smokers, and those born in Canada or the U.S. lost weight more slowly than those born elsewhere. Many other studies and reviews have shown similar results. Since the scientific evidence does not support a definite association between breast-feeding and postpartum weight loss, new mothers should be advised that breast-feeding in and of itself should not be relied upon to compensate for excessive pregnancy weight gain or to increase postpartum weight loss. How, then, do we counsel new mothers in their quest to lose pregnancy-related weight? Appetite suppressants such as phentermine are not recommended if a mother is breast-feeding. Although there are no reports describing the use of phentermine during lactation, it has a low molecular weight and therefore excretion into breast milk would be expected. The safest approach is a calorie restriction of 500-1000 calories per day. Although it has been documented that postpartum dieting to achieve moderate weight loss does not impair lactation, at least one study has shown a reduction in milk production with even short-term calorie restriction to less than 1500 calories per day. Therefore, as with all patients, individualizing the calorie restriction and providing close follow up is paramount to achieving optimal results. I base the patient’s plan for calorie restriction on estimated energy expenditure, which varies depending on initial weight, body composition and activity level. Lactation utilizes approximately 600 calories per day for production of 850 ml milk, but as discussed above, does not seem to result in increased weight loss. A calorie plan should provide 500-1000 calories less than the patient’s calculated requirements and include 75-90 g protein for satiety and preservation of lean mass. This level of calorie restriction is safely accomplished without appetite suppressants, and generally results in weight (fat) loss of about 1-2 lbs per week for most women whether breast- or bottle-feeding. Regarding exercise, a return to a regular exercise routine will enhance a patient’s weight loss. It may be challenging for a new mother to find the time and energy to exercise; however, exercise is known to elevate mood and relieve stress. Most new mothers may safely return to moderate cardiovascular activity and light resistance training following their 6-week postpartum visit. Combined with healthy dietary habits, regular exercise plays an important role in weight loss and maintenance; the key is to balance caloric intake and activity level to achieve a calorie deficit for weight loss, and equilibrium for weight maintenance. In addition to giving guidance for postpartum weight loss, bariatricians must also be aware of current recommendations for weight gain during pregnancy, since many of our patients are of childbearing age. The Institute of Medicine recently revised the 1990 Nutrition During Pregnancy guidelines due to dramatic shifts in the demographic and epidemiologic profile of the U.S. population. The new guidelines are based on maternal pre-pregnant BMI, and are available on the IOM website. Of note in the introduction to the guidelines is data from the 2003-2004 round of the National Health and Nutrition Examination Survey (NHANES) showing that 28.9 percent of women of reproductive age (20-39 years old) were obese (BMI ≥ 30) and 8.0 percent were extremely obese (BMI ≥ 40). The revised guidelines recommend that all obese women restrict their gestational weight gain to no more than 20 lbs. The growing number of obese reproductive-age women (currently 30%) constitutes a large population of women needing counseling and guidance for weight loss prior to pregnancy, careful monitoring of pregnancy weight gain, and support in postpartum weight loss/maintenance. As bariatricians, it is our role to assess caloric and nutritional needs, and formulate a plan for safe and effective weight loss at all stages of the reproductive years. Ligue Internationale La Leche. Nutrition et allaitement. Publication #159FRC 1986. Quebec, Canada: Blessings Corporation, 1990. Haiek Laura N, MD, MSc, et al. Postpartum weight loss and infant feeding, J Am Board Fam Med. 2001;14(2). Lederman SA. The effect of pregnancy weight gain on later obesity. Obstet Gynecol 1993; 82:148-55. Briggs Gerald G, Freeman Roger K, Yaffe Sumner J, Drugs in Pregnancy and Lactation: a reference guide to fetal and neonatal risk, 8th Edition, Philadelphia: Lippincott Williams & Wilkins, 2008, p1470. Dusdieker LB, Hemingway DL, Stumbo PJ. Is milk production impaired by dieting during lactation? Am J Clin Nutr 1994;59:833-40. Strode MA, Dewey KG, Lonnerdal B. Effects of short-term caloric restriction on lactational performance of well-nourished women. Acta Paediatr Scand 1986;75:222-9. Thomson AM, Hytten FE, Billewicz WZ. The energy cost of human lactation. Br J Nutr. 1970 Jun;24(2):565–572. IOM (Institute of Medicine). Weight Gain During Pregnancy: Reexamining the Guidelines. Washington, DC: The National Academies Press. Posted online May 28, 2009.
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