This. Not only that, but seeing "over 5,000 changes" makes me question the thresholds they used to deem a change significant. Actually, I went and downloaded the paper (see here: http://www.cell.com/pb-assets/journals/research/cell-metabolism/on/cmet1935_r.pdf ). There's no replicates (technical or biological), they didn't subsample to identify conserved significant differences (how the hell can you subsample with 13 controls and 10 fats). The effects of the bariatric surgery were studied on SIX PEOPLE. That's it, three time points (one week before, one after, and one freaking year after), there's no controls for those either. This is a freaking joke, and it's quite shocking that this crap article got published on a journal with an impact factor of 17.