In an extraordinary exchange, former FDA commissioner David Kessler challenged NYU professor Marion Nestle about what we think we “know” about a healthy diet. This video is well worth watching.

The exchange crystalizes a very basic difference of opinion that exists among nutrition researchers today: those who question the basic tenets of our nutritional guidelines vs. those, such as Marion Nestle, who insist that we know what a healthy diet is and that obesity/diabetes continue to rise simply because Americans fail to follow it.

My own view is that we can no longer blame the American public and all people worldwide for failing to follow nutritional guidelines. This is not a plausible explanation, nor is it based on the best available data.

In this video, it is notable that Kessler acknowledges the failure of nutrition policy and states that obesity is the result of “metabolic chaos.” He also gives a nod to “insulin resistance” as playing a role in the etiology of type 2 diabetes, a more nuanced view than the calories-in-calories-out model of thinking which Nestle still promotes.

Kessler states:

“The obesity problem is worse than we’ve thought. It creates a kind of metabolic chaos…And we are clueless. We have no idea what interventions work. I think we have FAILED in giving nutritional advice to people. If diet and exercise worked, we’d all do it, and it wouldn’t be a problem. [Yet] it doesn’t work in the long run…. WE spend billions of dollars throughout many different departments. I’d go back to the very basics. At the National Institutes of Health, I’d set up a new institute on nutritional sciences. I would try to get answers to the very basic questions. Is a calorie a calorie? Can I eat unprocessed meat? What’s the basis of insulin resistance and diabetes? I think we have FAILED the American public on this basic information.”

He continues:

“We began processing foods in the 20s and 30s…and I think no one has a clue the effect of processing on human physiology. Something has driven all of us to get bigger and bigger. And we’re leading the world [in obesity], and we’re exporting it. And it’s coming from what we EAT, and we don’t fully understand it.”

Marion Nestle replies:

“I’m not sure we have to fully understand it. We know that the US production system produces twice the number of calories that we need. And people started eating more in 1980. And those calories have to be sold. We now consume between 300-500 calories more per day, and people gained weight. It’s not complicated! Some of that came from larger portions, and some of it came from food marketing. If you eat more you’re going to gain weight. I think we know what healthy diets are. They’re diets that contain a lot of fruits and vegetables, they’re balanced in calories, and they don’t contain a lot of junk food.”

Kessler counters:

“So why don’t we do it?”

Exactly. Many people strive faithfully to be healthier. We are not all lazy junk-food eaters. So why can we not improve our health? Conventional explanations are no long sufficient or convincing.

[Note: this is not a perfect transcription of the comments, but I hope they accurately reflect the speakers’ intent]