EATING TO LIVE OR LIVING TO EAT?

I was on a plane about two weeks ago coming home from Minneapolis, and I saw the guy in front of me reading the Wall Street Journal.  On the front page of the “Personal Journal” was the following article:

Eating to Live or Living to Eat?
Stomach vs. Brain:  Discovering Why Some People Can Resist Dessert While Others Can’t

Needless to say, it caught my attention.  When he was done reading it I asked him if I could take a look.  If he objected, I was going to take it anyway and then kick his ass for being a jerk.  Luckily for him, he didn’t object.

The premise behind the article was actually very interesting (why are some people “able” to resist dessert while others are seemingly “unable”).  They also used a scenario that hits very close to home…the office birthday party!  Ever since I entered corporate America, I have been “that guy” who never eats cake or brownies at someone’s mid-afternoon birthday celebration.  And I always get chastised for it, but it doesn’t bother me.  I actually enjoy it!  (Quick tangent:  for my birthday, some of my co-workers served raw veggies, hummus, and fruit, and everybody destroyed it and raved about how good it was.  For the next birthday, though, it was back to cake…how disappointing)

Basically what the article tells us is that there are two systems that govern hunger cues, the homeostatic system and the hedonic system.

Eating for Survival – The Homeostatic System
This system controls signals from your body to indicate that your body is lacking in something such as water, nutrients, or energy.

Eating for Pleasure – The Hedonic System
This system is governed by the reward system in your brain.  Simply seeing or smelling a food can result in the release of dopamine, which is a neurotransmitter that has many roles in the brain, one of which is reward.

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Scholars have understood the different motives for eating as far back as Socrates, who counseled, ‘Thou shouldst eat to live, not live to eat.’

Socrates:  Born 469 BC, Died 399 BC.  That’s a long time ago, but he was obviously onto something!

This reminds me of another of my favorite quotes, also from a Greek (but a physician, not a philosopher) who lived around the same time as Socrates:

“Let thy food be thy medicine and thy medicine be thy food.”
-Hippocates, known as the father of Western medicine:  Born 460 BC, Died 377 BC.

‘When obese people see high-calorie foods, a widespread network of brain areas involved in reward, attention, emotion, memory and motor planning is activated, and all the areas talk to each other, making it hard for them to resist,’ says Susan Carnell, a research psychologist at the New York Obesity Research Center at Saint-Luke's-Roosevelt Hospital and Columbia University and one of the investigators.

I really dislike this comment.  Perhaps this is truly a “chicken or the egg” scenario, but I doubt it.  The researcher gives the impression that obese people react differently to seeing the foods simply because they are obese.  I tend to believe that certain people react differently to seeing foods and as a result (over time) they have become obese.

Studies have found that a diet of sweet, high-fat foods can indeed blunt the body's built-in fullness signals.  Most of them emanate from the digestive tract, which releases chemical messengers including cholecystokinin, glucagon-like peptide and peptide YY when the stomach and intestines are full.  Those signals travel up to the brain stem and then the hypothalamus, telling the body to stop eating.

This concept was the main premise behind the book The End of Overeating.  More specifically, how the food industry manipulates the combination of sugar, fat, and salt in foods to influence the quantity of food people eat.

Obesity also throws off the action of leptin, a hormone secreted by fat tissue that tells the hypothalamus how much energy the body has stored.  Leptin should act as a brake against overeating, and it does in normal-weight people.  But most obese people have an overabundance of leptin, and somehow their brains are ignoring the signal.  All these findings beg the question, which came first? Does obesity disrupt the action of leptin, or does a malfunction in leptin signaling make people obese?

…are some people obese because their brains overreact to tempting food, or do their brains react that way because something else is driving them to overeat? Researchers at Yale and elsewhere are turning to such questions next.  ‘It's possible that these changes reflect how the brain has adapted to eating patterns in obese people, and that could create a vicious circle, putting them at risk for even more disordered eating,’ says Dr. Small.