Crunching massive amounts of data, involving billions of measurements, has offered up a detailed picture of the changes a human body undergoes during periods of weight gain. The research, led by a team of scientists from Stanford University, combined a variety of different biological profiling technologies to find weight changes in a human body affect everything from a person's microbiome and immune system, to their cardiovascular system.

"The goal here was to characterize what happens during weight gain and loss at a level that no one has ever done before," explains Michael Snyder, co-senior author on the study.

The research looked at 23 healthy participants, 10 with a normal sensitivity to insulin and 13 that were identified as insulin-resistant, a condition considered to be a precursor to type 2 diabetes where cells are unable to effectively process insulin. The information gathered on each subject spanned a broad cross-section of different fields the researchers labeled "multiple omics strategies." This included data on genes and gene expression, the bacterial composition of the microbiome, and information on protein production.

Baseline measurements were first gathered, and initial differences between the two sub-sets of participants were identified. The biggest disparity at the outset was the presence of inflammatory molecular markers in the blood of the insulin-resistant subjects. Snyder suggests this kind of molecular flag could be useful in the future to help better target those at risk of developing type 2 diabetes.

The next stage saw all the subjects placed on a high-calorie diet for a month, after which they had gained an average of 6 lb (2.7 kg). All the data profiles were again gathered, and despite the modest weight gain recorded, several molecular shifts were observed.

One of the most notable changes identified in all participants post weight gain was a systemic inflammatory response. Raised inflammation markers were seen across several different pathways, including protein production and gene expression, but interestingly this response was mostly reversed quickly when the participants lost that weight.

The most unexpected change the researchers noted was the activation of a gene pathway associated with a condition called dilated cardiomyopathy, a type of heart failure.

"That was quite surprising. I didn't expect 30 days of overeating to change the whole heart pathway," says Snyder. "But this all fits with how we think of the human body – it's a whole system, not just a few isolated components, so there are systemwide changes when people gain weight."

The study is perhaps most significant for the way it incorporates new data collection methods and crunches those big volumes of data to uncover functional observations. These detailed molecular studies not only shed light on the systemic changes that modest weight gain can cause, but point physicians towards a future where big data can personalize medicine to focus precisely on the biology of individual patients.

"Big data will be critical to the future of medicine, and things like these integrative omics profiles will offer an understanding of how the human body responds, in a very personal way, to different challenges," says Snyder. "I think it will be a critical part of managing human health in the future."

The study was published in the journal Cell Systems.

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