The number of overweight children, adolescents and adults is rising markedly. Obesity in children and adolescents predicts obesity in adult life, it predicts morbidity and mortality decades later, it is associated with cardiovascular risk factors, orthopaedic conditions and lower self-esteem and once present it is hard to treat. Preventing obesity is therefore of primary concern.
Nursing mothers who breastfeed for longer amounts of time may be helping their babies avoid weight troubles later in life, according to research.
Results gleaned from 17 studies over the last 39 years suggest an association between the number of months babies are breastfed and the risk of being overweight.
"One month of breastfeeding was associated with a 4 percent decrease in risk (of being overweight)," concludes Dr. Thomas Harder and colleagues in the study, published in the American Journal of Epidemiology.
"These findings strongly support a dose-dependent association between longer duration of breastfeeding and decrease in (the) risk of (being) overweight."
Adolescents who were breastfed for at least seven months were 20% less likely to be overweight than those breastfed for three months or less (odds ratio 0.80, 95% confidence interval 0.67 to 0.96). These results were adjusted as above.
There was an estimated 8% reduction in the risk of adolescent overweight for every additional three months of breastfeeding (with the highest category being nine months or more) (odds ratio 0.92, 95% confidence interval 0.87 to 0.98).
Investigators analyzed numerous studies dating back to 1966 up to 2005, looking at overweight rates for children who were breastfed and those who were exclusively fed with formula. After nine months of breastfeeding, the effect on being overweight plateaued, the researchers found.
Adolescents who were mostly or only fed breast milk in the first six months had a 22% lower risk of being overweight (odds ratio 0.78, 95% confidence interval 0.66 to 0.91) than adolescents who were mostly or only fed formula. These results were adjusted for the childrens age, sex, sexual maturity, energy intake, time spent watching television, physical activity, birth weight and birth order; the mothers body mass index, smoking, dietary restraint and weight cycling; and estimated household income.
Study authors did not outline specific reasons for the linkage between breastfeeding and being overweight. But some researchers believe breastfed babies are more familiar with signals of "fullness" than formula-fed babies, prompting them to stop feeding.
Two studies seem to disagree whether breastfeeding can reduce the risk of overweight in children. However, considering both studies, it may be the combination of mothers breastfeeding with having an optimum body mass index (implicating sharing healthy lifestyle habits with their children such as diet and physical activity) that reduces the risk of childhood overweight.
Gillman et al study found that breastfed babies are less likely to become overweight adolescents than formula fed babies and the protective effects are larger with longer periods of breastfeeding. In contrast, Hediger et al study did not find any association between breastfeeding and subsequent obesity.
In both studies maternal obesity is related to childhood/adolescent obesity implicating the role of genetic and environmental factors, such as shared lifestyle habits, e.g. diet and physical activity patterns.
The finding that overweight and obese mothers were less likely to breastfeed (perhaps because maternal adiposity prevents successful initiation or maintenance of breastfeeding) provides a further suggestion that it is a combined effect of maternal overweight with the absence of breastfeeding that results in an increased risk for becoming overweight in later years.
"The mechanisms by which breastfeeding affects the risk of (being) overweight are still unclear," the study states. "(However), breastfeeding results in a lowered body weight gain during the critical neonatal periods, obviously caused by a lower mean caloric intake in breastfed infants, compared with formula-fed neonates ."
Scientific evidence has shown that breast milk contains all the essential nutrients and elements needed to nurture the healthy growth of a baby for the first six months of life. However, additional vitamin D supplementation is usually recommended by doctors for babies who are exclusively breastfed.
Additionally, Breast milk is already acknowledged as the best food for babies, giving unique immunological, growth and developmental benefits. If there is a chance that it can help prevent childhood obesity then this should be promoted, paying special attention to overweight mothers who are less likely to breastfeed and may need additional support with initiating and maintaining breastfeeding.
Breast milk is well suited for a baby's delicate digestive system and is rich in antibodies, which help fight off bacteria and viruses. The Canadian Paediatric Society recommends that all newborns be exclusively breastfed for the first six months of life and that the nursing can continue for two years or more.
Also, breast feeding seems to have a influence on the mothers body mass index as well. Mothers who fed their babies only breast milk in the first six months had the lowest average body mass index (24.5 kg/m2). Mothers who fed their babies only formula had the highest average body mass index (25.7 kg/m2).
Mothers who breastfed their babies for a longer period had a lower average body mass index than mothers who breastfed for shorter periods, e.g. mothers who breastfed for at least seven months had an average body mass index of 24.6 kg/m2 compared with 25.7 kg/m2 for mothers who breastfed for three months or less.
Mothers body mass index predicted their childrens weight. Mothers with a body mass index of more than 30 kg/m2 were 27% more likely to have an overweight adolescent than mothers whose body mass index was less than 25 kg/m2 (odds ratio 0.27, 95% confidence interval 0.21 to 0.33).
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