As some Pacific island cultures have “westernized” over the last several decades, among the changes has been a dramatic increase in obesity. Researchers don’t understand all the reasons why, but even a decade ago in American Samoa 59 percent of men and 71 percent of women were obese. A new Brown University study finds that the Samoan epidemic of obesity may start with rapid weight gain in early infancy.
The implications of the study published online in the journal Pediatric Obesity may not be confined to Polynesian populations, said the authors. American Samoa’s prevalence of obesity in infancy may be the harbinger of a slower-moving trend in the same direction in developed nations. Places like the mainland United States, after all, are the origin of the more sedentary, calorie-rich lifestyle that has largely replaced subsistence fishing and agriculture in American Samoa.
“One of the reasons we think Samoa is interesting is really because we think the level of obesity there could actually foreshadow what we see here in the United States and other high-income nations if we continue the way that we’re going,” said study lead author Nicola Hawley, a postdoctoral research fellow in the Alpert Medical School at Brown University and the Weight Control and Diabetes Research Center.
To conduct the study, Hawley and her co-authors examined the medical records of nearly 800 American Samoan babies born between 2001 and 2008. The babies were all singleton births, carried to term of 37-42 weeks.
In particular, the team tracked the babies’ growth, weight gain, and whether they were breastfed, given formula or a mix of both. They used the data to plot the trajectories of infant weight gain up to 15 months of age.
The researchers made several main findings:
One in five newborns qualified for a diagnosis of macrosomia — excessive birth weight of more than 8.8 pounds or 4 kilograms.
By 15 months of age 23.3 percent of boys and 16.7 percent of girls were obese (based on being heavier than the U.S. CDC’s 95th percentile). A further 16.1 percent of boys and 14.0 percent of girls were overweight.
At 15 months, 38.6 percent of formula-fed boys were obese while only 23.4 percent of breast-fed boys were obese.
Stephen McGarvey, research professor of epidemiology and the study’s senior author, said the babies were perhaps less heavy at birth than one might expect given the prevalence of obesity among their mothers, but the subsequent weight gain in early infancy was the study’s most important finding. Rapid weight gain in infancy is widely understood to be a risk factor for adult obesity.
The median weight gain among the Samoan babies in the first four months of life was 978 grams a month, McGarvey said. That figure is almost 20 percent more than the 820 grams a month documented in a prior study of babies on the U.S. mainland.
The Samoan babies’ average weight gain curve, he said, resembled the trajectory epidemiologists see among undernourished babies who suffer intrauterine growth restriction, meaning they are nutritionally deprived in the womb but then compensate by gaining weight rapidly after birth. Samoan babies are not undernourished, McGarvey said, but they may also be somehow constrained in their growth as fetuses, perhaps because they are at an upper limit of growth before birth.
“We wonder whether this response is not partially a response to the events in utero,” said McGarvey. He and Hawley plan to pursue that question in future research.
Hawley noted that while the seemingly protective effect of breastfeeding has been shown in other studies, the results bolster the case for the idea that it extends to non-European populations. The finding also suggests a specific tactic — encouraging breastfeeding throughout more of infancy — that public health officials can employ in stemming infant obesity, at least in boys.
The researchers acknowledged that further research is required to understand why the benefits of breastfeeding were not seen in girls.
Most importantly, McGarvey and Hawley said, the study indicates that in a population with prevalent obesity such as in American Samoa, excessive weight begins in infancy.
Additional authors on the study are William Johnson of the University of Minnesota and Ofeira Nu’usolia of the Tafuna Clinic of the American Samoa Department of Health.
The National Institutes of Health (grants: R25-TW008102, R18-DK075371, and R01-HL093093)) and Brown University funded the study.
Editors: Brown University has a fiber link television studio available for domestic and international live and taped interviews, and maintains an ISDN line for radio interviews. For more information, call (401) 863-2476.
David Orenstein | EurekAlert!
One gene closer to regenerative therapy for muscular disorders
01.06.2017 | Cincinnati Children's Hospital Medical Center
The gut microbiota plays a key role in treatment with classic diabetes medication
01.06.2017 | University of Gothenburg
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
23.06.2017 | Physics and Astronomy
23.06.2017 | Physics and Astronomy
23.06.2017 | Information Technology