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- WELCOME TO THE FOURTH SECTION
IN OUR SERIES ON ENERGY BALANCE AND OBESITY.
AND IN THIS SECTION I'M GOING TO BE COVERING REGULATION
OF APPETITE, HUNGER, FOOD INTAKE, AND SATIETY.
LET'S START BY TAKING A CLOSER LOOK AT THIS CHART.
AND STARTING WITH BEFORE WE HAVE ANY FOOD INTAKE,
THAT POINT OF HUNGER.
I WANT TO DISCUSS HUNGER FOR A MINUTE.
BECAUSE HUNGER IS ACTUALLY A PHYSIOLOGIC NEED FOR FOOD,
A NEED FOR CALORIES AND FOOD NUTRIENTS
TO PROVIDE US WITH CALORIES.
WHEN THERE IS NO FOOD IN THE STOMACH,
GHRELIN, WHICH IS A HORMONE, IS RELEASED.
AND THIS IS THE HORMONE
THAT CAUSES THOSE STOMACH CONTRACTIONS,
THAT STOMACH GROWLING YOU FEEL WHEN YOU HAVEN'T HAD FOOD.
GENERALLY IT'S ABOUT 4-6 HOURS.
GHRELIN ALSO TRAVELS TO THE BRAIN AND SIGNALS
THE BRAIN TO SAY, "HEY, WE NEED TO GET SOME FOOD."
IN ADDITION, THERE ARE ALSO
NO NUTRIENTS GOING INTO THE BLOODSTREAM.
AND ALTHOUGH THERE MIGHT NOT BE A DIRECT SIGNAL,
THERE ARE NO INHIBITORY SIGNALS WHICH WOULD INHIBIT HUNGER.
SO WE HAVE A FEW MECHANISMS THAT CAUSE US TO SEEK FOOD.
NOW APPETITE IS A LITTLE BIT DIFFERENT.
THERE'S SOME OVERLAP WITH HUNGER,
BUT A LITTLE BIT MORE ABOUT DESIRE FOR FOOD.
SO YOU CAN HAVE AN APPETITE FOR FOOD,
BUT ACTUALLY NOT BE HUNGRY.
SO THE SMELL OF FOOD AND THE SIGHT OF FOOD
WILL ACTUALLY STIMULATE SOME OF THE BRAIN ENDORPHINS,
AND WILL INCREASE THAT DESIRE OR URGE OR NEED FOR FOOD.
SO YOU CAN WALK INTO A ROOM AFTER HAVING A FULL MEAL,
AND IF SOMEONE IS BAKING CHOCOLATE CHIP COOKIES
AND YOU LOVE CHOCOLATE CHIP COOKIES,
YOU MIGHT BE STUFFED, BUT ALL OF A SUDDEN
YOU HAVE A DESIRE OR AN APPETITE FOR A CHOCOLATE CHIP COOKIE.
SO THERE ARE THINGS THAT,
IN ADDITION TO HUNGER, CAN INCREASE APPETITE.
AND ALSO CAUSE THIS FOOD-SEEKING BEHAVIOR.
SO THERE IS A DRIVE FOR US TO SEEK FOOD.
AND THIS DRIVE,
PARTICULARLY WITH HUNGER, IS VERY STRONG.
BECAUSE WE HAVE NOT HAD FOOD ABUNDANCE THROUGHOUT HISTORY,
WE'VE HAD FOOD SCARCITY,
OR PERIODS OF FOOD SCARCITY.
SO HUNGER IS A VERY STRONG DRIVE
BECAUSE IT'S BEEN A SURVIVAL INSTINCT FOR US.
SO WITH OUR FOOD-SEEKING BEHAVIOR
AND THEN WE START EATING, THE CONTINUED EATING,
WE ACTUALLY TALKED ABOUT THIS, BOTH WITH SERVING SIZES,
EATING, PORTION SIZES, HOW MUCH WE EAT,
AND WHY WHEN WE REVIEWED SOME OF DR. BRYAN WEINSTEIN'S
RESEARCH EARLIER IN THIS SEMESTER.
BUT THE PRESENCE OF OTHERS, THAT SOCIAL STIMULATION,
THERE ARE OTHER PEOPLE AROUND YOU, EATING.
REMEMBER IN THE MOVIE THEATER WITH THE STALE
POPCORN AND HOW PEOPLE ATE IT EVEN THOUGH THEY DIDN'T LIKE IT?
WELL, THAT WILL CAUSE YOU TO EAT, OR CONTINUE EATING.
HOW [ INAUDIBLE ]
AN ENVIRONMENT IS, THE TYPE OF MUSIC THAT'S BEING PLAYED,
THE TIME OF DAY, IT'S 6:30, IT'S TIME FOR DINNER,
I'M NOT HUNGRY, BUT I SHOULD EAT.
SO THOSE ARE CUES TO HAVE US EAT OR CONTINUE EATING.
AND OF COURSE THERE'S THE ABUNDANCE OF FOOD.
IF YOU ARE AT A DINNER PARTY AND THERE'S A TABLE
FULL OF FOOD AND THERE ARE A LOT OF PORTIONS AROUND,
PEOPLE ARE EATING, YOU MIGHT BE FULL,
BUT YOU MIGHT CONTINUE TO SERVE
YOURSELF MORE AND CONTINUE TO EAT.
AND THIS IS SOMETHING THAT IMPACTS
THE AMOUNT OF FOOD THAT WE EAT--
EITHER THE DRIVE FOR FOOD,
OR THE AMOUNT THAT WE ARE CONTINUING TO EAT.
BUT WHAT ABOUT SATIETY?
SATIETY IS THAT FEELING OF FULLNESS.
AND IT'S NOT AS STRONG OF A DRIVE FOR US AS, I MEAN,
OUR SIGNALS ARE NOT AS STRONG AS THE HUNGER SIGNAL.
AND IF YOU THINK ABOUT THROUGHOUT HISTORY,
WE HAVE 2-1/2 MILLION YEARS ON THIS PLANET OF EATING,
AND HUNGER AND GETTING THOSE CALORIES IN IS
GOING TO BE A MUCH STRONGER DRIVE THAN
THAT SATIATION OR THAT FEELING OF FULLNESS.
NOW FIRST, WHEN YOU EAT FOOD AND IT GOES INTO THE STOMACH,
THE STOMACH WILL EXPAND.
WHEN THERE'S FOOD IN THERE,
THAT SENDS THE STRETCH RECEPTORS THAT ACTUALLY
SIGNAL THE BRAIN AND GO TO THE SATIETY CENTER AND SAY,
"OKAY, WE'VE GOT FOOD IN THE STOMACH."
AND THIS IS IMPORTANT BECAUSE THE TYPE OF FOOD THAT YOU'RE
EATING IS GOING TO HAVE A BIG IMPACT ON THIS.
FOODS SUCH AS, SAY, ICE CREAM ACTUALLY HAVE
A VERY LOW SATIETY RATE, BECAUSE, FOR ONE,
THEY'RE NOT REALLY GOING TO STRETCH OUT THE STOMACH AT ALL.
IF YOU EAT, REMEMBER THAT PLAIN BAGEL I KEEP REFERRING TO?,
OR IF YOU EAT A PIECE OF, YOU KNOW, SOME BREAD, THAT IS,
AND WHEN YOU PUT THAT REALLY HIGHLY REFINED, SAY,
WHITE BREAD INTO YOUR MOUTH, IT JUST MELTS, RIGHT?
I MEAN, THERE'S NOT A LOT OF CHEWING THAT HAS TO BE DONE.
THAT IS GOING TO GO INTO THE STOMACH,
THERE'S VERY LITTLE FIBER, WITH NOT A LOT OF EXPANSION,
IT'S ALREADY STARTED BREAKING DOWN
BEFORE IT EVEN GETS TO THE STOMACH.
SO THAT'S NOT GOING TO HAVE A
BIG STRETCH REFLEX ON THE STOMACH.
BUT WHAT ABOUT FRUITS AND VEGETABLES?
WHAT ABOUT IF YOU ATE A BIG SALAD?
OR IF YOU HAD SOME BROCCOLI OR ASPARAGUS?
AND THOSE ARE VERY FIBROUS FOODS,
THEY HAVE A LOT OF CELLULOSE, THEY HAVE INSOLUBLE FIBER,
SOME OF THEM HAVE SOME SOLUBLE FIBER TOO.
IF YOU HAD FRUITS OR AN APPLE, WELL,
THIS IS GOING TO CAUSE THAT STOMACH TO EXPAND.
AND THAT'S GOING TO CAUSE THOSE STRETCH RECEPTORS
TO SEND A SIGNAL TO THE BRAIN THAT YOU'RE FULL.
BEFORE THAT FOOD EVEN GETS TO THE DIGESTIVE PROCESS,
OR EVEN GETS TO THE INTESTINES.
SO THE TYPE OF FOOD YOU EAT IS GOING TO MAKE A DIFFERENCE.
AND I HEARD SOMEBODY SAY THIS ONCE,
SO I'M GOING TO STEAL THEIR TERM,
BUT WE'VE GOTTEN TO A POINT IN OUR SOCIETY
WHERE A LOT OF OUR FOOD IS ALMOST PRE-CHEWED.
I MEAN, YOU PUT IT INTO YOUR MOUTH,
IT'S HIGHLY PROCESSED, IT'S HIGHLY REFINED,
YOU'VE TAKEN OUT, YOU KNOW, THE FIBER,
THERE'S NOTHING LEFT TO CHEW, IT MELTS IN YOUR MOUTH.
WELL, THAT PRE-CHEWED, THAT PROCESSED FOOD,
THOSE HIGHLY REFINED CARBOHYDRATES AND PACKAGED,
PROCESSED PRODUCTS DON'T INVOLVE A LOT OF WORK BY THE MOUTH.
THEY DON'T HAVE A LOT OF IMPACT ON OUR SATIETY,
SO WE'RE GOING TO EAT MORE OF THEM.
IF YOU STICK MORE WITH YOUR WHOLE FOODS,
YOU'RE GOING TO HAVE MORE OF AN IMPACT ON YOUR SATIETY.
WHEN THE NUTRIENTS ACTUALLY GET INTO THE INTESTINES,
THERE ARE A COUPLE OF IMPORTANT HORMONES,
WHICH I DON'T REQUIRE YOU TO KNOW,
THAT WILL SIGNAL THE BRAIN THAT THERE'S FOOD IN THE INTESTINES.
AND ONE WILL JUST BASICALLY SAY,
"THERE'S SOME FOOD IN THE INTESTINES,"
SO GIVE AN IDEA OF ABOUT HOW MUCH
FOOD IS COMING INTO THE INTESTINES.
AND IT SLOWS THE EMPTYING OF THE STOMACH.
AND YOU THINK ABOUT THE STOMACH EMPTYING HERE,
THIS IS KIND OF A COLON HERE, BUT WITH THE SMALL INTESTINES,
IF YOU SLOW THE EMPTYING OF THE STOMACH, IT DOES TWO THINGS.
ONE, IT ENHANCES THE DIGESTION AND OF THE
BREAKDOWN OF THOSE FOOD PRODUCTS INTO INDIVIDUAL
NUTRIENTS WHICH WILL ENHANCE ABSORPTION,
SO THE BODY WILL GET MORE OUT OF THAT FOOD.
IT INCREASES EFFICIENCY.
THE AMOUNT OF FOOD GOING INTO OUR SYSTEM THAT WE CAN ABSORB.
BECAUSE IT'S NOT GETTING OVERLOADED ALL AT ONCE.
SO THAT'S VERY IMPORTANT.
BUT IT ALSO INCREASES SATIETY.
SO THE MORE THAT YOU HAVE IN YOUR STOMACH,
AND THE LONGER IT'S THERE,
THE LESS YOU'RE GOING TO HAVE THIS GHRELIN BEING SECRETED,
SO YOU'RE GOING TO HAVE FOOD IN THERE FOR LONGER,
SO YOU HAVE BASICALLY NOW TWO
WAYS THAT YOU'RE GETTING SATIETY.
BUT ALSO, THERE'S ANOTHER HORMONE,
SPECIFICALLY WHEN FAT COMES INTO THE INTESTINES,
THAT SIGNALS THE BRAIN.
SO WHEN YOU EAT FAT, IT'S ACTUALLY SATIATING.
I KNOW WE'VE TALKED ABOUT HOW FAT IS NOT BAD,
FAT IS GOOD FOR US AND HAS MANY FUNCTIONS IN THE BODY.
ANOTHER KEY WITH SATIETY IS THAT FAT WILL INCREASE SATIETY
BY CAUSING THE SIMULATION OF THIS HORMONE THAT'S
GOING TO TRAVEL TO THE BRAIN, AND SAY,
"HEY, WE'VE GOT FOOD.
DON'T NEED TO EAT ANYMORE."
SO IT TELLS THE BRAIN YOU'RE FULL.
SO WE DO HAVE
SOME OTHER SIGNALS AS WELL.
AND THE LAST ONE IS,
ONCE THOSE NUTRIENTS GO INTO THE BLOODSTREAM,
SO WE BRING THE NUTRIENTS DOWN, THEY GO INTO THE STOMACH,
WE HAVE THE STRETCH RECEPTOR, [ INAUDIBLE ]
GOES TO THE BRAIN, OKAY,
WE HAVE FOOD IN THE STOMACH, SECONDLY WE HAVE FOOD COMING
INTO THE INTESTINES THAT SLOWS THE ABSORPTION OF
THE STOMACH EMPTYING THAT ALSO HELPS WITH SATIETY.
THIRD, FAT IN PARTICULAR BY SOME
OTHER NUTRIENTS HAVE A LESS EFFECT,
ALSO SEND A HORMONE TO THE BRAIN THAT SAYS, "WE'RE FULL."
LASTLY, BREAKING DOWN THAT FOOD INTO ITS INDIVIDUAL NUTRIENTS,
THAT GETS ABSORBED INTO THE BLOODSTREAM.
NOW REMEMBER, ALL FOOD, CARBOHYDRATE AND PROTEIN,
WILL HAVE AN IMPACT ON INSULIN RELEASE FROM THE PANCREAS.
THE GREATEST RELEASE WILL BE FROM,
OF COURSE, OUR CARBOHYDRATES, GLUCOSE.
BUT ANY FOOD THAT COMES IN ACTUALLY
WILL CAUSE A RELEASE OF INSULIN.
INSULIN, IN ADDITION TO BRINGING GLUCOSE INTO THE
BODY CELLS FOR ENERGY, WILL TRAVEL TO THE BRAIN
AND ALSO GO TO THE SATIETY CENTER AND ESSENTIALLY SAY,
"WE NOW HAVE FOOD IN THE BLOODSTREAM."
SO WE HAVE THREE FACTORS AT WORK.
NOW REMEMBER, YOU PROBABLY HEARD,
WAIT 20 MINUTES AFTER A MEAL, TO SEE IF YOU'RE FULL.
WELL, PART OF IT IS THE STRETCH RECEPTOR REFLEX IS PRETTY QUICK.
LET'S REMEMBER,
OTHER HORMONAL SIGNALS ARE NOT AS FAST, YOU KNOW,
PARTICULARLY WHEN WE THINK ABOUT THE ACTION OF INSULIN.
IT'S ACTUALLY GOING TO TAKE QUITE A WHILE BEFORE,
DEPENDING ON WHAT YOU EAT,
BEFORE YOU'RE ACTUALLY GOING TO GET THAT EFFECT.
SO IT IS GOOD TO SIT BACK, RELAX,
AND SEE IF YOU ACTUALLY ARE STILL HUNGRY.
NOT THAT YOU HAVE AN APPETITE FOR
MORE FOOD BECAUSE IT LOOKS WONDERFUL,
IT SMELLS WONDERFUL, OTHER PEOPLE ARE EATING.
WERE YOU ACTUALLY HUNGRY?
DO YOU HAVE A PHYSIOLOGIC NEED FOR MORE FOOD?
AND YOU DO HAVE TO GIVE YOUR BODY A MINUTE OR TWO TO--
ACTUALLY, MORE THAN A MINUTE OR TWO,
THEY SAY 20 MINUTES, IT MIGHT BE A LITTLE BIT LONGER,
AND IT'S GOING TO VARY BASED ON WHAT YOU EAT--
TO ACTUALLY HAVE THOSE SIGNALS BE PROCESSED.
NOW I WANT TO GO OVER A LITTLE BIT OF RESEARCH BECAUSE THESE
ARE FACTORS THAT CAN DRIVE OUR BEHAVIOR TOWARD EATING.
AND THIS IS OUT OF AN ARTICLE IN THE
AMERICAN JOURNAL OF CLINICAL NUTRITION.
AND WHAT THEY LOOKED AT WERE THE TYPES
OF FACTORS THAT ACTUALLY CAUSED US
TO INCREASE OUR DRIVE TO OBTAIN FOOD.
SO IT'S THAT DRIVE OR DESIRE FOR FOOD.
THEY FOUND OUT THAT THE TOP THREE WERE ALCOHOL CONSUMPTION,
SLEEP DEPRIVATION, AND TELEVISION.
NOW I WANT TO JUST START WITH OUR NORMAL STATE,
AND THIS IS WHAT THEY HAVE DETERMINED,
THAT SOME OF THESE BEHAVIORS REALLY DECREASE OUR
INHIBITORY CONTROL OVER OUR NORMAL DRIVE TO EAT.
BECAUSE NORMALLY WE HAVE A BIG INHIBITORY CONTROL.
WE DO HAVE THIS DRIVE TO EAT BECAUSE
IT'S A SURVIVAL MECHANISM.
THAT'S HOW WE LASTED 2-1/2 MILLION YEARS,
BEFORE THE LAST HUNDRED YEARS OF FOOD ABUNDANCE.
A HUNDRED OR MORE.
BUT WE DO HAVE AN INHIBITORY CONTROL.
THERE'S A MECHANISM THAT SAYS,
"SLOW DOWN," YOU KNOW, IN OUR NORMAL STATE.
WHAT OUR CONDITIONED MEMORY IS,
IS THAT LET'S JUST SAY, WHEN YOU COME HOME FROM WORK,
YOU DIDN'T SLEEP WELL LAST NIGHT,
YOU HAD A LONG DAY, YOU GRAB A BEER,
AND YOU SIT IN FRONT OF THE TELEVISION.
AND IN YOUR MEMORY, YOU REMEMBER HOW FANTASTIC
IT WAS TO MUNCH ON THAT BOWL OF CHIPS.
SO THAT'S, YOU KNOW, PART OF YOUR MEMORY.
[ INAUDIBLE ]
IS THAT THERE'S MORE OF THAT DESIRE,
AN INTENSE DESIRE TO HAVE THOSE CHIPS WHILE YOU'RE WATCHING TV.
AND THAT DESIRE IS WHAT REALLY DRIVES YOU TO EAT THAT.
NOW, IF YOU CAME HOME FROM WORK, YOU KNOW,
YOU'D HAD A GOOD NIGHT'S SLEEP, YOU HAD A GOOD DAY AT WORK,
YOU DON'T SIT IN FRONT OF THE TELEVISION,
YOU DON'T HAVE ANY ALCOHOL,
MAYBE YOU'RE GOING TO GO OUT FOR A WALK WITH YOUR DOG,
YOUR CONDITIONED MEMORY MAY NOT BE
AS STRONG FOR HAVING THOSE CHIPS,
AND THEREFORE YOU'RE NOT GOING TO REALLY HAVE THAT DESIRE.
AND THERE'S A REALLY BIG INHIBITORY
CONTROL IN THIS NORMAL STATE.
WHAT THEY FOUND IS THAT AS SOON AS YOU ADD IN THAT ALCOHOL,
AS SOON AS YOU'RE SLEEP-DEPRIVED,
YOU'RE WATCHING TELEVISION,
OR MAYBE YOU HAVE ALL THREE ALL AT ONCE,
YOU'RE INHIBITORY CONTROL IN YOUR BRAIN IS REALLY SMALL,
THIS GOES WAY DOWN.
SO YOU HAVE THIS REALLY INCREASED DRIVE TO EAT
BECAUSE THAT DESIRE BECOMES INTENSE.
SO YOU STILL HAVE THAT MEMORY OF HOW GREAT IT WAS TO SIT DOWN
WITH YOUR BEER AND YOUR CHIPS IN FRONT OF YOUR TV AND JUST GO,
"OHHH, I HAD SUCH A LONG DAY," THAT DRIVE,
THAT DESIRE, IS ACTUALLY GOING TO INCREASE.
AND THE ENJOYMENT INITIALLY OF THOSE
CHIPS IS GOING TO BE REALLY GOOD.
BUT WHAT THEY FOUND IS THAT IN THIS CHRONIC
RESPONSE IF YOU MAKE THIS A HABIT EVERY SINGLE DAY,
WHEN YOUR INHIBITORY CONTROL DEFINITELY CONTINUES TO GO DOWN,
THE MEMORY OF HOW GREAT IT WAS GOES UP,
YOUR DESIRE AND ENJOYMENT FOR IT GOES DOWN.
AND THIS IS WHAT IS VERY INTERESTING ABOUT THIS.
THIS IS VERY CLOSE TO DRUG-SEEKING.
THAT THE MEMORY FOR THIS ACTION, OR THE DRUG,
AND WE CAN SAY, OR THE FOOD, IS HUGE.
AND YOU ARE GOING AFTER THIS BIG DRUG-SEEKING BEHAVIOR,
BUT YOUR ACTUAL ENJOYMENT OF IT GOES DOWN.
AND THAT'S BECAUSE YOUR INHIBITORY CONTROL GOES DOWN,
THE MEMORY OF IT GOES UP.
THIS IS SOMETHING THAT IS GOING ON IN
YOUR BRAIN THAT YOU ARE NOT CONSCIOUS OF.
BUT IF YOU ENGAGE IN ANY OF THESE BEHAVIORS,
YOU MIGHT WANT TO STEP BACK AND THINK ABOUT IT.
YOU KNOW, IS THIS A CONDITIONED HABIT?
IS THERE A STRONG DRIVE FOR IT,
BUT IS YOUR ENJOYMENT OF THAT FOOD CONSUMPTION GOING DOWN?
'CAUSE THAT'S WHAT THEY HAVE FOUND.
IT'S VERY INTERESTING.
I'M GOING TO TALK A LITTLE BIT ABOUT LEPTIN BECAUSE
I HAD MENTIONED HOW OUR HORMONES DRIVE OUR BEHAVIOR.
AND LEPTIN IS ONE OF THOSE HORMONES.
AND IT ACTS, OF COURSE, WITHOUT YOU KNOWING IT.
BUT LEPTIN HAS THIS DRIVE
TO MAKE YOU MORE ACTIVE.
BUT, YEAH, IT'S SUPPRESSING YOUR APPETITE.
AND THAT LEPTIN IS ACTUALLY RELEASED BY FAT CELLS.
SO WHEN YOU HAVE MORE FAT ON YOUR BODY,
LEPTIN IS RELEASED, SAYING, "HEY,
WE'VE GOT STORES OF FAT,
YOU CAN NOW GO OUT AND DO SOME ACTIVITY,
YOU DON'T REALLY NEED TO EAT AS MUCH."
AND IF YOU THINK BACK TO OUR DAYS IN OUR SURVIVAL DAYS,
HOW WE GOT THIS FAR IN LIFE, IS WE NEEDED THOSE CONTROLS.
WE NEEDED SOMETHING TO TELL OUR BODY THAT IT'S OKAY TO EXERCISE,
YOU DON'T HAVE TO CONSERVE ENERGY,
YOU CAN GO OUT AND FORAGE FOR FOOD, OR-- .
AND YOU DON'T HAVE TO SIT DOWN AND FOCUS ON,
YOU KNOW, EATING FOOD AT THAT MOMENT.
SO IT IS A CONTROL MECHANISM.
NOW WHEN THE FAT GOES DOWN,
SO LET'S SAY THERE'S FOOD SCARCITY,
THERE'S GOING TO BE LESS LEFT, AND ALL OF A SUDDEN
THERE'S GOING TO BE MORE OF A DESIRE TO BE SEDENTARY.
AND THERE'S GOING TO BE AN INCREASED APPETITE.
YOU'RE GOING TO HAVE MORE OF A DESIRE OR A DRIVE FOR FOOD.
AND YOU MAY HAVE SEEN THESE MICE BEFORE,
AND THIS WAS INITIALLY DISCOVERED
AND IT WAS BY DR. JEFFREY FRIEDMAN,
THEY HAD DISCOVERED THE GENE THAT ACTUALLY IS
GOING TO CODE FOR OUR LEPTIN, THIS HORMONE.
IF YOU TAKE TWO MICE,
AND YOU CREATE TWO MICE THAT DON'T HAVE LEPTIN.
SO THEY ARE BORN WITHOUT LEPTIN.
AND THEY ACTUALLY BOTH GOT THIS BIG.
SO REMEMBER, WITHOUT THE LEPTIN THERE'S A DRIVE TO EAT,
AND YOU WANT TO BE SEDENTARY.
THIS MOUSE OVER HERE, IT GETS INJECTIONS OF LEPTIN,
THE MOUSE IS STILL PRETTY PUDGY, RIGHT?
IT'S STILL NOT A REALLY SKINNY MOUSE, BY ANY MEANS.
BUT THIS MOUSE GETS LEPTIN INJECTIONS.
THE LEPTIN IS GOING TO INCREASE ACTIVITY,
JUST NATURAL ACTIVITY,
AND IT'S GOING TO DECREASE APPETITE.
SO EVEN THOUGH THEY'RE GIVEN THE SAME AMOUNT OF FOOD,
THEY HAVE ACCESS TO THE SAME AMOUNT OF, YOU KNOW,
THE MOUSE WHEELS WHERE THEY CAN RUN AROUND,
ONE IS GOING TO CONSUME MORE AND MOVE LESS,
AND THE OTHER ONE IS GOING TO CONSUME LESS AND MOVE MORE.
AND IT'S ALL ABOUT LEPTIN.
SO WHEN IT WAS FIRST DISCOVERED,
THEY THOUGHT THIS WAS GOING TO BE THE MAGIC BULLET.
OH, MY GOD!,
PEOPLE MUST NOT HAVE LEPTIN.
WELL, THEY FOUND OUT THAT THIS IS VERY, VERY, VERY RARE,
FOR INDIVIDUALS TO BE BORN WITHOUT LEPTIN.
IN FACT, THERE'S ONLY BEEN A FEW INDIVIDUALS
IDENTIFIED AND THEY'VE DEFINITELY BEEN STUDIED.
IN FACT, OBESE PEOPLE TEND TO HAVE MORE LEPTIN.
BUT YOU'D THINK, IT'S COUNTERINTUITIVE,
IF THEY HAVE MORE LEPTIN, THEN WHY,
OR SHOULDN'T THEY BE MOVING MORE AND EATING LESS?
BUT IN THE SAME WAY THAT OVERWEIGHT INDIVIDUALS WILL
DEVELOP INSULIN RESISTANCE, OR INDIVIDUALS WHO ARE
JUST EATING A LOT OF REFINED CARBOHYDRATES,
EVEN BEFORE THEY BECOME OBESE, DEVELOP INSULIN RESISTANCE,
YOU CAN DEVELOP LEPTIN RESISTANCE.
REMEMBER, LEPTIN IS RELEASED FROM FAT CELLS.
SO THE MORE FAT YOU HAVE ON YOUR BODY,
THE MORE LEPTIN THAT IS RELEASED.
WELL, IF YOU HAVE THAT LEPTIN AND YOUR CELLS ARE
CONSTANTLY EXPOSED TO LEPTIN, WHAT HAPPENS?
THEY STOP ANSWERING.
YOU KNOW, IT'S THE BOY WHO CRIED WOLF--
YOU KEEP KNOCKING ON THE DOOR, LEPTIN KEEPS ON KNOCKING,
EVENTUALLY YOU'RE GOING TO IGNORE THE LEPTIN.
SO THERE'S A LOT OF LEPTIN THERE,
BUT THE CELLS AREN'T RESPONDING TO IT.
SO PEOPLE WHO ARE OVERWEIGHT OR OBESE TEND TO
HAVE INSULIN RESISTANCE AND LEPTIN RESISTANCE.
SO NOW WE HAVE THIS VERY LARGE HORMONAL
IMBALANCE THAT IS GOING TO INCREASE APPETITE,
INCREASE THE DRIVE FOR FOOD, IS GOING TO DECREASE
THE AMOUNT OF PHYSICAL ACTIVITY YOU WANT TO DO,
AND YOU CAN'T EVEN GET THAT ENERGY INTO THE
CELLS TO DO THE ACTIVITY EVEN IF YOU WANTED TO.
SO THESE ARE THE HORMONES THAT I'M
TALKING ABOUT THAT REALLY DRIVE OUR BEHAVIOR.
AND OF COURSE YOU HAVE TO GET TO THE POINT, FIRST,
YOU HAVE TO GET TO THE POINT WHERE THE FOOD,
THE TYPES OF FOOD THAT YOU ARE EATING CREATES THIS.
SOME PEOPLE CALL THEM METABOLIC DERANGEMENT,
AND SAY THAT IS A HORMONE IMBALANCE.
AND THEN GENERALLY THERE IS SOME ASPECT OF BEING
OVERWEIGHT OR OBESITY, AND CERTAINLY GENETICS MIGHT
INCREASE THE SUSCEPTIBILITY OF ONE WAY OR ANOTHER,
BUT OUR FOOD AND OUR ENVIRONMENT ARE A MUCH GREATER FACTOR.
I'M GOING TO MENTION THE THRIFTY GENE
AS ONE THEORY OF OBESITY,
AND IT'S CERTAINLY NOT UNIVERSALLY ACCEPTED.
BUT THE IDEA IS AN INTERESTING CONCEPT
BECAUSE GENES DO PLAY A ROLE IN OBESITY.
BUT IT'S JUST ONE FACTOR.
AND THE THRIFTY GENE, WHICH IS ESSENTIALLY SAYING
THAT IF WE LOOK BACK IN OUR, AGAIN,
OUR 2-1/2 MILLION YEARS OF EATING ON
THIS PLANET AND SURVIVAL, INDIVIDUALS WHO WERE ABLE
TO STORE MORE ENERGY AND BE MORE SEDENTARY,
AND TO HAVE LESS ABILITY TO ACTUALLY USE FAT AS FUEL,
AND HAD INCREASED CAPACITIES TO STORE FAT,
PROBABLY MADE IT THROUGH THE TIMES OF
FOOD SCARCITY BETTER THAN THOSE WHO DIDN'T.
AND INITIALLY IT WAS THOUGHT THAT THIS GENE WOULD HELP PEOPLE
GET THROUGH CERTAIN FAMINES AND, YOU KNOW,
WHEN THERE WAS NO FOOD AT ALL.
BUT THEY HAVEN'T FOUND OUT THAT EVERY
POPULATION HAS HAD BIG FAMINES IN THE PAST.
BUT IF WE JUST THINK ABOUT SURVIVAL IN TERMS OF FOOD
SCARCITY AND PROBABLY HAVING A BIG MEAL,
AND THEN YOU MIGHT GO WITHOUT SOME FOOD,
THEN YOU HAVE A BIG MEAL, WITHOUT SOME FOOD,
MAYBE LONG PERIODS WITHOUT A LOT OF FOOD,
SO OUR GENES ARE PROBABLY MORE ADAPT.
I MEAN, THE PEOPLE WHO SURVIVED THOSE PERIODS,
MORE ADAPT AT STORING ENERGY, THEY'RE GOOD AT IT,
THEY'RE GOOD AT STORING THE FAT.
BUT VERY BAD AT USING THE FAT.
THEY'RE GOOD AT BEING SEDENTARY,
HAVING THE TENDENCY TO CONSERVE THEIR ENERGY.
SO NOW WE WANT PEOPLE TO MOVE.
BUT BACK THEN, IF YOU DIDN'T HAVE TO MOVE,
YOU DIDN'T WANT TO MOVE, YOU WANTED TO CONSERVE ENERGY,
YOU MAY NOT KNOW WHERE YOUR NEXT MEAL IS.
AND A DIMINISHED ABILITY TO USE DIETARY FATS AS FUEL.
SO IF YOU CAN STORE ENERGY BETTER,
BUT YOU CAN'T REALLY USE THAT ENERGY THAT WELL,
AND YOU HAVE MORE OF A CAPACITY FOR IT,
SO THOSE PEOPLE SURVIVED.
AND SOME PEOPLE THINK THAT MAYBE 65%
OF OUR POPULATION HAS A THRIFTY GENE,
MORE BETTER EQUIPPED FOR THIS SURVIVAL.
IT ALSO HAPPENS TO BE ABOUT THE AMOUNT OF
PEOPLE WHO ARE OVERWEIGHT, OBESE, AND MORBIDLY OBESE.
AGAIN, SO THIS IS AN INTERESTING IDEA,
AND IT MAY NOT, WE MIGHT SEE SOME VARIATIONS ON IT,
BUT IT'S NOT NECESSARILY A UNIVERSALLY ACCEPTED THEORY.
THERE ARE A LOT OF FACTORS THAT CONTRIBUTE TO OBESITY.
I DO WANT TO MENTION "NEAT".
AND THIS IS A TERM COINED BY DR. JAMES LEVINE.
AND IT STANDS FOR NONEXERCISE ACTIVITY THERMOGENESIS.
SO THIS IS NOT ABOUT DOING EXERCISE,
GOING OUT AND JOGGING OR RUNNING, RIDING A BICYCLE.
IT'S MORE ABOUT A LOW ENERGY EXPENDITURE.
AND WHAT HE FOUND FROM DOING THIS
RESEARCH IS THAT PEOPLE WHO ARE FIDGETY.
ARE YOU SOMEONE WHO'S SITTING THERE AND YOU'RE
WATCHING THIS AND MAYBE YOU'RE BOUNCING A LEG,
OR YOU'RE TAPPING YOUR FINGERS, YOU KNOW, OR YOU DO THIS.
IF YOU ARE A FIDGETY PERSON,
YOU ACTUALLY BURN MORE CALORIES THROUGHOUT THE DAY.
AND HE FOUND THAT PEOPLE WHO ARE MORE
FIDGETY ALSO TEND TO BE THINNER.
HE TRACKED PEOPLE AND THEIR ENERGY,
AND HE ACTUALLY HAS THESE BODY SUITS THAT PEOPLE
HAVE TO WEAR ALL THE TIME, SLEEPING, DURING AWAKE,
AND IT HAS SENSORS ON IT AND IT TRACKS EVERY SINGLE
MOVEMENT AND MOTION THROUGHOUT THE DAY.
AND HE COULD CALCULATE THAT MOTION AND HOW
MANY CALORIES THAT THEY ACTUALLY BURNED.
AND THERE ARE SOME PEOPLE WHO WERE NATURALLY MORE FIDGETY.
SO HE SAYS YOU CAN'T CHANGE THAT.
PEOPLE ARE EITHER FIDGETY OR THEY'RE NOT.
'CAUSE WHEN YOU'RE FOCUSED ON SOMETHING,
YOU CAN'T ALSO BE FOCUSED ON FIDGETING,
YOU MIGHT DO IT FOR MAYBE 10 SECONDS AND THEN STOP.
BUT HE THINKS, AND THIS WOULD GO ALONG WITH THE
THEORY OF CALORIES-IN, CALORIES-OUT,
WHICH I TALKED ABOUT COULD BE FLAWED,
BUT WHAT HIS RESEARCH HAS SHOWN IS THAT THOSE FIDGETY
PEOPLE TEND TO BE THINNER, THEY ARE BURNING MORE CALORIES.
BUT YOU CAN INCREASE YOUR NEAT,
YOUR NONEXERCISE ACTIVITY THERMOGENESIS,
BY DOING SIMPLE THINGS SUCH AS, AND YOU CAN SEE HIM BACK HERE,
THIS IS DR. LEVINE, HE IS ON A TREADMILL.
HE CALLS THIS THE WALKING DESK, AND HE HAS HIS COMPUTER SET UP.
AND HE'S NOT WALKING FOR EXERCISE,
AS IF YOU WERE AT A GYM.
HE'S GOING AT A VERY SLOW PACE,
TO WHERE IT DOES NOT INTERRUPT ANY OF HIS WORK,
HE'S NOT BREAKING A SWEAT.
WHAT HE FOUND PERSONALLY FROM THE EXPERIENCE WAS,
HE HAD MORE ENERGY THROUGHOUT THE DAY,
HE DIDN'T GET THAT TIRED FEELING AFTER LUNCH,
HE FELT MORE MENTAL ACUITY BECAUSE HE WAS MOVING MORE.
AND I THINK THIS IS A FANTASTIC IDEA,
THE IDEA THAT A LOT OF US, YOU KNOW,
AS WE SIT HERE AT OUR COMPUTERS ALL DAY,
OR MAYBE YOU'RE STUDYING, AND WE DON'T HAVE THE
SAME OPPORTUNITIES TO MOVE AS WE USED TO,
THAT INCORPORATING IDEAS LIKE THIS CAN,
NOT INCREASE YOUR CARDIOVASCULAR FITNESS,
BUT THEY'RE JUST GOING TO INCREASE
THE AMOUNT OF ENERGY EXPENDITURES--
SO THE ENERGY-OUT SIDE OF THE EQUATION.
NOW REMEMBER, EVEN THOUGH I TALKED ABOUT THEIR
FLAWS IN THE CALORIES-IN, CALORIES-OUT THEORY,
THE FIRST LAW OF THERMODYNAMICS DOES REMAIN
TRUE ABOUT CALORIES-IN DOES EQUAL CALORIES-OUT,
IT'S JUST THE [ INAUDIBLE ] IS THE CAUSE AND EFFECT.