Sunday, November 26, 2006

Snake-oil Infomercial on PBS

My local PBS affiliate is running a pledge drive, running rather different programming from its usual fare. Right now, they're running what amounts to an infomercial for snake oil, in the person of Dr. Mark Hyman and his "Ultra-Metabolism" plan for "automatic weight loss." He makes a number of valid points: skipping breakfast will make you gain weight, Americans don't eat enough fiber, we should eat leaner protein, there are good fats and bad fats, and we should exercise more. However, mixed in with those bits of truth are some half-truths, misdirections, and outright falsehoods that set off my bullshit detector repeatedly. Most especially, he talks about the "new science of nutrigenomics" that will "reprogram your genes" to help you lose weight. I'll puncture some of his marketing hype, and also tell you the true secret to healthy and sustainable weight loss.

"Hi, I'm Dr. Mark Hyman, and I'm here to tell you how to use revolutionary new science, the science of nutrigenomics, to reprogram your genes to automatically lose weight and regain your health. ... You literally can reprogram your genes by changing the way you eat ... During this program, I'm going to teach you about the myths that make you gain weight ... 'Now, what is he talking about?,' you might be saying. 'I thought genes were something you got from your parents. ...' But no, genes are every moment, every second, interacting with your body, interacting with your environment, with the food you eat, with the stress you're under, with the thoughts you have. Everything is turning messages on or off in your DNA that literally controls your metabolism." Well, first of all, it's not a "myth": your genes are something you got from your parents. Saying that your genes are "interacting" with your environment, however, is a myth. "Interacting" means that your genes act upon the environment, and the environment acts upon your genes, but neither of those is actually happening. Indeed, you absolutely and categorically cannot "reprogram" your genes by eating differently. The genes you were born with are the genes you will die with, except for any that might get garbled by mutation or viruses or cancer. What Dr. Hyman actually means is that you can affect the genetically programmed responses of your body by changing your circumstances and your environment. If you are hot, your genes have programmed your body to perspire, but moving from the arctic to the tropics is not "reprogramming" those genes. It is simply giving different input to your body, which has genetically determined responses.

"If we understand this new concept, that we can use food, that we can change our environment, that we can change the way we live in our lifestyles, to literally communicate messages to our DNA, to turn on health and weight loss, then we have the problem of obesity solved." Well, no, actually you can't "literally communicate messages to your DNA." It's a nonsensical assertion. To be specific, your DNA has no receptors with which to receive "messages" from your food or your body or your environment.

I promised you the true secrets of weight loss, though, so here they are:
  • Eat when you're hungry, but don't eat when you're not hungry.
  • Stop eating when you're satisfied, not when you're absolutely stuffed.
  • Eat healthy, nutritious food, in reasonable portions, with modest amounts of "treats" like candy and desserts.
  • addendum: Eat slowly and chew your food thoroughly. If you rush through eating a meal, your stomach doesn't have time to send a signal to your brain that it's full, making it easy to eat too much before you realize it. Eating slowly also gives you the opportunity to savor your food — your taste buds get the same joy with less food. Finally, eating slowly and chewing thoroughly improves your digestion.
  • Exercise regularly.
All of the above is just common sense, not some magic bullet or secret elixir of health. Some of Dr. Hyman's specific advice is right on the mark: eat more fiber, less processed food (especially processed sugar and the dreaded duo of transfat and high-fructose corn syrup), more fresh vegetables, and sensible, regular meals. Skipping breakfast is very bad, and for exactly the reason Dr. Hyman gives: your body's natural reaction to food deprivation is a starvation response — lower metabolism and the impulse to binge at the next opportunity. Filling up on candy, freedom fries, soft drinks, Twinkies, and all the other forms of junk food obviously leads to weight gain, but if you deny yourself all junk food, you're unlikely to stick with the plan. When you feel the desire for a treat, make it a small one, and make some of your treats non-junk food. A piece of fruit is sweet and juicy and flavorful, but much better for you than a Ding-Dong. You can still have the occasional outright indulgence, but not with every single meal. Make your treats, especially the less nutritious ones, less frequent so that they are more special.

The secret is that it's all vastly "easier said than done." You won't have sustainable weight loss by going on a crash diet. You have to make real and lasting changes in your eating and exercise habits, and there is no way around that reality.

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