A tale of calories

I have been seeing this preview for a reality TV show for weight loss called The Biggest Loser. It is supposed to launch the participants on a strict regimen of physical training and exercise and whoever loses the most, wins. About 10 years ago, who would have ever thought that a TV show on massive and simultaneous calorie reduction would be such a big hit? But it was just a matter of time. In this age of what I call “Oprah-naissance” — unabashed public exposé and cathartic processing of what used to be (better left) unsaid or even taboo — a show about the actual weight of our human desires, was just waiting for the right treatment and TV executives.

I have nothing against The Biggest Loser. It highlights the role of willpower in achieving goals. And that is not bad but it may be good to look to science as to how will power works.

Willpower is not something that we conjure from sheer bravura. It comes from a physical part of ourselves — in our brains. And our brains are both made up of what we were born with (genes) and what we make of it (connections we make while we live and learn). And scientists from Caltech think they have found at least one spot where “willpower” hangs out in our heads.

The study was published last May 1 in the journal Science and was entitled: The work described in the Science paper, “Self-Control in Decision-Making Involves Modulation of the vmPFC Valuation System.” They showed pictures of food to volunteers who called themselves “dieters” and were asked to rate foods according their “tastiness.” Afterwards, they were asked to choose between these foods and a “neutral” food (food that is not so tasty but not so bad either). They did all these while inside MRI machines.

The scans showed two brain parts that got activated when it comes to the choice of foods. One is the ventromedial prefrontal cortex (vmPFC) and the dorsolateral prefrontal cortex (DLFPC). The vmPFC seems to be the brain part that is all alight in glee when it comes to choosing food based on its yum factor. This vmPFC is always active when you see yummy food whether you are a faithful dieter or not. But what was the difference between those who had self-control and those who did not? It was that other part of the brain (DLFPC) — like the voice of your mother when you were a kid reminding you always to eat your vegetables. The DLFPC seems to be the seat of willpower as far dieting is concerned. Those who exercised self-control had their DLFPCs lighting up so that these same subjects were able to balance the lure of flavor with the health benefits of a particular food choice. But the scientists also cautioned that your DLFPC cannot be such a superhero that it can make you eat healthy things that you dislike in the first place. There may be some other brain part for that.

Another thing that bears on weight loss may be the pace at which you get those spoonfuls into your mouth. Livescience.com reported last Nov. 4 of this study yet to be published in January 2010 in the Journal of Clinical Endocrinology & Metabolism. Essentially, it explains that it takes some time after you have swallowed your food before your guts release the hormones that would reach your brain to let you realize that you are already full. The researchers said that it ranges from 12 minutes from thin people to 20 minutes from obese ones. The experiment had the subjects all eat a cup of ice cream during two different sessions. The sessions were either five minutes or 30 minutes for the ice cream to be eaten. Then, the researchers took blood samples from eaters at the start of the snack and at 30-minute intervals for the next three and a half hours. It turned out that the slow eaters had higher concentrations of peptide YY and a glucagon-like peptide — the two hormones that the gut makes and sends to the brain to signal that we have had our fill. In addition, they found that the slow eaters also rated their “fullness” higher than the fast eaters.

I am sure that there is a lot more to losing weight than just the untiring encouragement of a faithful trainer, a very diligent DLPFC and the slow pace of your spoonfuls. But for now, this is the science dish I can offer based on recent findings.

The human story is innately rich in drama and even our relationship with wheat or white bread and the whole world of calories become a fascinating story because what we eat affects our health which in turn affects who we are and how we live. We each live out our own tales of calories, televised or not, and there science could help make the story clearer, more understandable and maybe, just maybe, really healthier.

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