A potential explanation
could lie
in thetrillions of microbes
that reside in the gut. In 2009,
Rosa Krajmalnik-Brown from Arizona State University
in Tempe and her colleagues
sequenced
the bacterial genes present in faeces from three people who had received a gastric bypass. Compared with obese and normal-weight controls,
their guts contained proportionally fewer bacteria
from the usually abundant Firmicutes phylum,
and excess levels of the Gammaproteobacteria class8.
“Even with that small sample size
we were able to get statistically significant differences
because the microbiota changed so drastically
Krajmalnik-Brown says.