Preventive Medicine: Diet guidance veers from variety

Dr. David Katz

Dr. David Katz

The holidays are coming in hot (figuratively, and courtesy of climate change, literally as well), with Thanksgiving now under two weeks away. So, of course, all thoughts turn to…weight control.

Against that backdrop comes a bit of timely advice, in the form of a Science Advisory, courtesy of the American Heart Association. Their tip regarding diet and weight is this: variety is not your friend. Let’s consider how obvious it already was.

Have you ever been to an all-you-can-eat buffet? Have you ever not overeaten at an all-you-can-eat buffet? Has anyone ever not overeaten at an all-you-can-eat buffet? I don’t think so.

Back to the holidays, let’s consider that upcoming Thanksgiving feast. The common experience, I believe, is to eat until we can eat no more. That’s my plan, certainly, both because our annual feast is great, and because my mother would be disappointed otherwise. So, taking one for the team — I will stuff myself in the traditional manner.

But then a funny thing happens on the way to the Alka Seltzer. I said we eat until we can eat no more, but that’s not quite true. When we can eat no more, we can still eat…dessert. There is usually just enough time between “I couldn’t eat another bite,” and “what’s for dessert” to let out our belts out a notch or two.

That phenomenon is not a hollow leg or extra stomach, but rather a very well-studied trait of the human appetite center, called sensory specific satiety. We tend to fill up in a food and flavor-specific manner. But cross over from the salty, savory delicacies of the Thanksgiving meal to the sweet enticements of the dessert table, and a whole new appetite is activated.

Perhaps we can capture it all by borrowing a well-known aphorism: familiarity breeds satiety. The perilous corollary is that variety is a goad to gluttony.

This, in effect, is what the American Heart Association concluded. We have long had dietary guidance emphasizing the value of variety, and in their new Science Advisory, based on a thorough review of relevant evidence, the Heart Association is saying: not so much. There is no clear evidence of health benefit by increasing dietary variety, while the risk of weight gain rises with the length of your grocery list.

Linking this to grocery lists is directly germane. The inventory of the typical supermarket in the United States in the 1970s was roughly 15,000 products. Now, it is nearer to 50,000. Who can name the 35,000 new fruits and vegetables introduced over recent decades?

No one, because that hasn’t happened. Rather, food manufacturers have done three things primarily to expand our dietary choices so copiously. First, they have used the same four ingredients — wheat, soy, rice, and corn (and, importantly, sugar made from corn) — to create thousands of products. This is not genuine dietary diversity; it is pseudo-diversity. The products vary, but the composition of the products varies barely if at all. Most of the alleged “variety” in modern diets is of this type.

Second, manufacturers have exploited every sequential, equally silly variant on the theme of dietary savior or scapegoat (e.g., fat, carbohydrate, fructose, gluten, GMOs, etc.) to capture the public imagination to create whole new inventories of much the same junky food, tweaked to address the worry-du-jour, as in: sure, they are cookies — but they are gluten free now! Eat them all!

Third, manufacturers have the option of varying the marketing collateral — the banner ads, the nutrient claims — even if the products don’t really vary. Sometimes, we wind up with several versions of much the same concoction because the packaging graphics vary; kids’ cereals are a sad example.

Thousands upon thousands of nutrient compounds are found in vegetables, fruits, grains, nuts, seeds, beans, and legumes. Dietary variety would not be perilous to beltlines and biomarkers in a world where dietary offerings were all actual food. With its updated guidance, the Heart Association is conceding that world is not ours. Where variety often means different shades of lipstick on the same, small parade of pigs; willful manipulation; and new ways to eat badly — it’s time to veer from variety. When you find real food, mostly plants — go for it, and carpe diem. The rest of the time, caveat emptor.