Is a Varied Diet Over-rated?

Over the past ten or twenty years, scientists have spent a lot of energy investigating the world’s healthiest and longest-lived populations, trying to figure out what they are doing right. Why do they live so much longer and have vastly lower rates of cancer, heart disease, diabetes, and other diseases than Western countries?  We’ve picked apart and analyzed the traditional diets and lifestyles of Okinawans, Cretans, Icelanders, Cameroons, Pima Indians, and so forth, in an attempt to codify, once and for all, the healthiest diet.

The problem is that health and longevity are about the only things that these cultures have in common. 

The robust Tarahumara Indians, for example, eat a diet of 80% carbohydrates (mostly in the form of starchy vegetables like corn and potatoes!), while the indestructible Cretans get almost 50% of their calories from fat.  Some long-lived cultures eat almost no meat, while the hale and hearty Icelanders eschew vegetables as “animal feed” and eat large quantities of lamb and fish.

Here’s one thing that indigenous diets do tend to have in common: They’re all composed of a relatively small list of foods. In most cases, about two dozen foods provide 95% of the calories–in some cases,  fewer than a dozen! Compare this with the tens of thousands of food products we are confronted with at the grocery store. Hundreds of kinds of produce from every climate in the world. Dozens of kinds of grains.  Scores of protein sources.  We think nothing of eating Indian food on Monday, Chinese on Tuesday, sushi on Wednesday, Latin-American on Thursday and Greek on Friday.

I’ve talked before about the benefits of a varied diet. But just last week, I wrote about a study suggesting that a highly varied diet is associated with higher body weight. And we do tend to eat more when confronted with a large variety of foods than we do when we eat just one or two things at a meal. (Think of your behavior at buffets, or at Thanksgiving.)

How about this: When it comes to vegetables, fruits, nuts, legumes, fish, nuts, herbs and other nutrient-dense foods, go for lots of variety! But when it comes to sweets, treats, highly processed snack foods, alcohol, and other empty calories, the less variety, the better!