Just as insulin is the “air conditioner” for
safe blood glucose levels, glucagon functions
as the “heater,” preventing blood sugar levels
from falling too low and giving us access to
energy we’ve previously stored. When the
body senses a dip in normal blood sugar
levels, alpha cells in the pancreas release
glucagon. Glucagon then tells the body to
break down stored fat and convert stored liver
glycogen (and, if necessary, protein from your
muscles) into glucose, trickling it into the
bloodstream to provide you with energy and
keep blood sugar levels normal.
There is a caveat.
Glucagon can tell the cells to release
stored energy—and use body fat—only when
there’s not a lot of circulating insulin. After
all, if insulin is elevated, nutrients are being
stored as fast as they’re being mobilized—or
faster. Which means that when insulin levels
are elevated (even moderately), the net effect
is more energy storage than energy access.