Genetics of obesity: Why we’re never going to find one diet that’s right for everyone

Wednesday, September 16, 2009 15:37
Comments Off on Genetics of obesity: Why we’re never going to find one diet that’s right for everyone

Any regular reader of this blog knows that we spend a lot of time debating the merits of various dietary theories. One of the reasons I sometimes find this debate frustrating (even tiresome) is that so many of the arguments boil down to this:

"Diet X has completely cured my diabetes (heart disease, weight problem, gout, wobbly upper arms, etc.).  Based on my experience, I'm convinced that Diet X is the one and only road to optimal health."

The problem is that "Diet X" may be a low-carb diet, a Paleo diet, a vegan diet, a raw diet, or any number of other mutually exclusive systems. At that point, the conversation starts to resemble discussions of religion or politics. Everyone spends a lot of energy proving their own point of view and trying to disprove alternate views. Some arguments are more articulate and compelling than others.  But in the end, few minds are changed.

In Defense of Wishy-Washiness

Perhaps you think I've been wishy-washy because I don't endorse one side or the other. After all, I've read the arguments and evidence. And I keep saying things like "Do What Works for You" and "One Size Doesn't Fit All." Shouldn't I have reached some sort of conclusion, even tentative, about which approach is "right," or at least "better"?

I really don't think there is one dietary prescription that is right for everyone. Part of this is simply pragmatic: It's a waste of time pitching a caveman diet to a committed vegan. But we're also beginning to see that genetics plays a big role in eating patterns.

Is it the carbs making my jeans so tight? Or my genes?

For example, some argue that eating carbohydrates disrupts the body's ability to regulate appetite and signal satiety (fullness)–leading to overeating and obesity.  As elegant as some of these diet/disease theories are, I don't think that the phenomenon of obesity (or its absence) can be fully explained by nutritional biochemistry alone. 

Recent research suggests that genetic variation also plays a
significant role in how much we eat and whether or not we gain weight,
or develop diabetes or heart disease. Here's a recent review article on the work in this field. (Subscription or library access required to view the entire article.)

The smart money now is on mapping out these genetic variations so that we can better predict who will fare well on what type of dietary prescription.  And here's a perfect example: This study suggests that a low-fat diet may be the best choice for people with a certain "obesity" gene.  Those with a double copy of the FTO gene are 2.5 times more likely to be obese. However, a low-fat diet neutralizes the effect of the gene.

In the meantime, people may need to try different eating patterns to find the one that is a good fit with their lifestyle and personal preferences.but allows them to maintain a healthy body weight over the long term.

Whither the Food Pyramid?

Many have questioned the validity of the U.S. Food Pyramid and Dietary Guidelines. But most simply want to replace them with pyramids and guidelines which better represent their own dietary dogma.  However, as nutritional genomics matures, one-size-fits-all efforts like the Food Pyramid and Dietary Guidelines may become less and less relevant.

Your thoughts?

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