Abstract
Loss of excessive weight that was gained during pregnancy can be a concern for some nursing mothers. In general diet, exercise, and behavior modification are the preferred methods of weight loss. Although drug therapy is not the most desirable method, it can be effective in producing short-term weight loss. This column reviews the drugs used for weight loss and their use during lactation.
Drugs for Weight Loss
Several classes of drugs are marketed for weight loss in the United States. Unfortunately, most of them have not been studied in nursing mothers.
Sympathomimetic amines
This group of drugs includes benzphetamine, diethylpropion, phendimetrazine, and phentermine. Only diethylpropion allegedly has information that it is excreted into breast milk according to one manufacturer's package insert, but no details are given and no published information could be located. Benzphetamine and phentermine are chemically similar to amphetamine. Their package inserts state that since amphetamines are excreted into milk, these two drugs should not be used during nursing. However, studies on the use of amphetamine for maternal narcolepsy during nursing found that milk levels were low and the breastfed infants were not adversely affected. Phendimetrazine information states that it “should not be taken by women who are nursing unless, in the opinion of the physician, the potential benefits outweigh the possible hazards,” neither of which are delineated. Pseudoephedrine is a sympathomimetic that reduces milk production markedly, even after one dose. It is not known if these other sympathomimetic drugs can reduce milk production, but it is a possibility.
The combination product of phentermine plus topiramate is considered among the most effective weight-loss drug products, but its package insert information is similar to the phentermine wording. Topiramate is excreted into milk and results in infant plasma levels of 10–20% of their mothers' plasma levels.
Orlistat
Orlistat is a lipase inhibitor that works by inhibiting fat absorption, which can result in flatulence with discharge, oily spotting, and fecal urgency after consumption of high-fat foods. Consequently, drug discontinuation is frequent. But orlistat is minimally absorbed from the gastrointestinal (GI) tract and has a short half-life of 1–2 hours, so it is unlikely to affect the breastfed infant. Because orlistat inhibits absorption of fat-soluble vitamins, mothers should take a multivitamin supplement at bedtime to avoid vitamin deficiency in themselves and their infants.
Lorcaserin
Lorcaserin is a unique selective serotonin 5-HT2C receptor agonist that suppresses appetite. It is a schedule IV controlled substance. No information is available on its excretion into milk or effects on the nursing infant or lactation. It is considered to be contraindicated during breastfeeding.
Bupropion–naltrexone
This fixed-dose combination product is FDA approved for weight loss. The combination has not been studied, but the drugs have been studied individually. Maternal bupropion doses of up to 300 mg daily produce low levels in breast milk and would not be expected to cause any adverse effects in breastfed infants. Naltrexone is minimally excreted into breast milk and not considered to be of concern in breastfeeding, although the amount of published information is small. It has poor oral bioavailability, at least in adults, which provides an extra margin of safety.
Liraglutide
Liraglutide is an injectable glucagon-like peptide-1 (GLP-1) receptor agonist. GLP-1 receptor agonists delay gastric emptying and cause satiety. Liraglutide is FDA approved for weight loss as well as for type 2 diabetes. No information is available on the excretion of liraglutide into milk or clinical use of liraglutide during breastfeeding. Because liraglutide is a large peptide molecule with a molecular weight of 3,751 Da, the amount in milk is likely to be very low and oral absorption is unlikely because it is probably destroyed in the infant's GI tract.
Herbal products
A number of herbals have been used in weight-loss products. The most common include green tea (Camellia sinensis), guarana (Paullinia cupana), bitter orange (Citrus aurantium/naringin), Garcinia cambogia, Hoodia gordonii, ginger (Zingiber officinale), ginseng (Panax ginseng/quinquefolius, Eluetherococcus senticosus), fennel (Foeniculum officinale), glucomannan (Amorphophallus konjac), licorice (Glycyrrhiza glabra), and willow bark (Salix alba).
Most of these products have not been studied in nursing mothers. Based on their known ingredients, though, some predictions can be made. Both green tea and guarana contain caffeine and they are sometimes found in the same product. High maternal doses of caffeine can cause fussiness and excitability in breastfed infants. Bitter orange contains synephrine and octopamine, which are sympathomimetics, somewhat similar to those discussed previously. They can potentially affect the infant or reduce lactation. Garcinia contains hydroxycitric acid, which is thought to inhibit the enzyme involved in conversion of carbohydrate to fat. It has also been associated with numerous cases of hepatotoxicity, so it should be avoided. Ginseng is not recommended during nursing because of its possible estrogenic actions. Willow bark contains salicylate, which can adversely affect infants in high doses. It is also best avoided during lactation.
Ginger, fennel, and licorice are all purported galactogogues that have been used in nursing mothers. Evidence for their efficacy either as galactogogues or weight-loss agents is weak, but they do not appear to be particularly toxic during breastfeeding. Glucomannan is not absorbed from the GI tract, so it is not of concern during nursing.
As with all dietary supplements, these supplements do not require premarketing approval from the U.S. Food and Drug Administration. Manufacturers do not need to prove the safety and effectiveness of dietary supplements before they are marketed. Product content can also vary between manufacturers or lot to lot.
Weight Loss During Lactation: A Special Situation
An interesting and somewhat sobering phenomenon that occurs during breastfeeding is that of the excretion of fat-soluble contaminants into milk. Many lipid-soluble environmental contaminants are stored in body fat. Some of these are very persistent in the environment and in the body and are referred to as persistent organic pollutants (POPs). Insecticides such as dichlorodiphenyltrichloroethane (DDT), its metabolite dichlorodiphenyldichloroethylene (DDE), and hexachlorocyclohexane (HCH), the fungicide hexachlorobenzene (HCB), as well as the electrical insulators, polychlorinated and polybrominated biphenyls (PCBs and PBBs) are not eliminated well from the body and can potentially accumulate over a lifetime of exposure.
Rapid weight loss after bariatric surgery results in much higher levels of POPs in the serum. The specific POPs that increase depend on the age of the person because they were exposed to different POPs over their lifetime—some prevalent in the 1940s and 1950s were subsequently banned. 1 These pollutants can partition into milk because of its fat content, potentially lowering the maternal body burden. Primiparous mothers who breastfeed may excrete more of these products into milk than multiparous mothers. For example, a small study found primigravida mothers excreted 15% more DDT and 230% more HCH into their milk than women who had breastfed a previous child. 2 However, results of studies are somewhat mixed and possibly dependent on the specific POP. 3
Rapid weight loss may mobilize contaminants stored in body fat to a greater extent than slow weight loss. Trans fatty acids, obtained mostly in the diet from hydrogenated vegetable oils in processed foods, are also stored in body fat unmetabolized and excreted into breast milk. One study found that the trans fatty acid content of milk was nearly double in women who lost 4–7 kg for a 9-week period than in those who lost 0–2 kg for the same time period. 4 A recent study of Swedish mothers found that weight loss was correlated with the amounts of DDE, HCB, and PCBs in their milk, with milk concentrations increasing the most in those who lost the most weight. 5 Because infants began supplementation during the study period, their intake of POPs from milk remained relatively constant for the lactation period.
So, although mothers may have little control over the amounts of fat-soluble contaminants stored in their body fat, they can control their rate of postpartum weight loss. Aggressive weight loss during lactation appears to be undesirable. Fortunately, many POPs and trans fatty acids are being eliminated from the environment and diet, so younger mothers may have lower amounts of these stored in body fat than older women.
Summary
Drugs are not the preferred method of weight loss, and information on them during breastfeeding is almost nonexistent. Several of them might cause adverse effects on the infant or on lactation itself. Nonabsorbable products such as orlistat and the herbal glucomannan (and other gums and fibers) are probably acceptable during breastfeeding. Women with postpartum depression might find the bupropion–naltrexone combination products helpful for both depression and weight loss. Women with type 2 diabetes might benefit from liraglutide, although there is no information on its use during nursing. Excessive or rapid weight loss during breastfeeding might transmit larger amounts of POPs to the breastfed infant.
Footnotes
Acknowledgments
The author thanks Cheston Berlin, MD, and Judy LaKind, PhD, for their review of the article and helpful suggestions.
Disclosure Statement
No competing financial interests exist.