room outfitted with instruments that measure how their
bodies use air, food, and water under different conditions—
show that whether you eat two meals a day or six your
metabolic rate is exactly the same. This is liberating because
the approach of eating fewer and larger meals provides
lifestyle flexibility, allows us to feel full, reduces decision
fatigue, and helps keep the amount of time insulin is
circulating to a minimum. Be aware, though, that as you
adjust to fewer and larger meals, it may take at least a few
days for your stomach to stop sending out signals saying
“It’s time to eat!”
Leptin: The Metabolic Throttle
Hormone
Sleep can also negatively affect another hormone
involved in hunger called leptin. Leptin is the “satiety”
hormone that helps regulate energy balance by inhibiting
hunger, and it plummets with sleep deprivation. Leptin’s job
is to control energy expenditure through its action on the
hypothalamus, the brain’s master metabolic regulator.
Because leptin is secreted by fat cells, the more fat cells one
has, the more circulating leptin. The brain interprets higher
levels of leptin as permission to open up the throttle a bit on
the rate at which our bodies burn calories—after all, food is
seemingly plentiful! But as with insulin, chronically elevated
leptin can cause leptin resistance to develop, and the signal
of “satiety” and the positive benefits of leptin on metabolism
becomes lost.
This is the unfortunate paradox faced by those who lose