Weight and Nuts

Sometimes people do research and then write it up in a way that reveals that they had preconceived notions about the results. An example of this is a recent report suggesting that eating nuts may help you to lose weight. The report was presented at the American Heart Association's November meeting.

OK, that makes sense. Most nuts contain a lot of fat, and fat slows down gastric emptying, so you feel full longer.

The study involved a food-frequency questionnaire, which can be fairly inaccurate. Who remembers everything they ate last week, or even yesterday? But that's not the problem I'm concerned with.

The researchers said the nuts were eaten "in place of foods generally considered low in nutritional value." So it's not just eating nuts but eating nuts in place of junky foods. One assumes they mean empty calories in sugary drinks or starchy highly processed foods.

But wait! They said "Substituting one serving a day of any type of nuts in place of one serving of red meat, processed meat, French fries, desserts or potato chips was associated with less weight gain over the four-year intervals."

Red meat is low in nutritional value? Since when?

According to P. G. Williams at the University of Wollongong, Australia,

"Lean red meats are:

"• An excellent source of high biological value protein, vitamin B12, niacin, vitamin B6, iron, zinc and phosphorus 
"• A source of long-chain omega-3 polyunsaturated fats, riboflavin, pantothenic acid, selenium and possibly also vitamin D
"• Mostly low in fat and sodium [this analysis refers to meat with fat trimmed]
"• Sources of a range of endogenous antioxidants and other bioactive substances including taurine, carnitine, carnosine, ubiquinone, glutathione and creatine."


This study was done in the lab of Walter Willett, who has long opposed eating red meat, and I suspect that because the researchers consider red meat to be unhealthy, they just lumped it in with foods considered low in nutritional value. This is not good science.

Even perfectly done nutritional studies can be confusing because so many factors are involved. Eating more of X usually means eating less of Y, so if the results are different, which was the crucial factor? Most people, including professional dieticians, make errors when reporting what they ate. And of course there are interactions between foods. Maybe food A has one effect when eaten with Food B but not when eaten with food C. And so forth.

So to see a misleading statement like the above in a report from Harvard is discouraging.

Will we ever know what the healthiest diet is? Probably not, because what works for one person may not work for another. What makes blood glucose go up for one person may not for another. And a diet that person A can stick to for years might be different from a diet person B could tolerate long term.

Our best approach is to try different diets and see how they affect our daily blood glucose levels and less frequent lab results and then choose one that works for us.

And it's probably also a good idea to try to ignore popular press articles about diet, which are often slanted to favor some marketing group. The nut study was funded in part by the California Walnut Commission.