Understanding Ultra-Processed Foods
Based on the work of Robert Lustig, a pediatric endocrinologist and author
Dr. Robert Lustig argues that one of the biggest problems with the modern diet isn't simply fat, carbohydrates, or calories. It is the enormous amount of ultra-processed food we eat.
Ultra-processed foods are industrial formulations that often contain refined ingredients, additives, flavorings, and other substances not typically used in home cooking. Many packaged snacks, sugary drinks, sweets, and fast foods fall into this category.
Lustig is particularly concerned about added sugar, refined carbohydrates, and lack of fiber. He argues that these foods can contribute to Insulin Resistance, fatty liver, obesity, and other metabolic problems.
His alternative is remarkably simple:
Eat Real food.
What I find useful about Lustig's message is that we don't have to decide whether every individual nutrient is good or bad. A practical place to start is simply to ask:
“How much of what I'm eating is actually real food?”
What Makes Ultra-Processed Food Different?
Processing itself isn't necessarily a problem. Cooking, freezing, fermenting, canning, and pasteurizing are all forms of processing.
Ultra-processing generally refers to industrial formulations made largely from refined or extracted ingredients and additives.
Processing can remove fiber, concentrate carbohydrates and fats, and make food easier and faster to consume.
An apple, for example, is different from apple juice. The intact fruit contains fiber and physical structure that affect how quickly its sugars are consumed and absorbed.
For Lustig, how food is constructed matters.
Sugar, Fiber, and the Liver
Lustig is particularly concerned about added sugar, especially when large amounts are consumed rapidly in sugary beverages and processed foods.
He argues that excessive sugar can contribute to liver fat and Insulin Resistance, particularly in the setting of excess calorie intake.
Fiber works differently. It slows digestion and provides food for parts of the gut microbiome.
This is the idea behind one of Lustig's favorite summaries:
Protect the liver. Feed the gut.
An Important NIH Experiment
One of the strongest experiments on ultra-processed food was conducted at the National Institutes of Health.
Participants lived in a research facility and were offered either an ultra-processed or an unprocessed diet. They were allowed to eat as much as they wanted.
On the ultra-processed diet, people spontaneously consumed about 500 more calories per day and gained weight. On the unprocessed diet, they ate less and lost weight.
The experiment doesn't show that every ultra-processed food is harmful. But it provides strong evidence that the foods we eat can influence how much we naturally want to eat.
Not Everything in a Package Is Bad
The term ultra-processed includes foods with very different nutritional characteristics. A packaged whole-grain bread, flavored yogurt, protein product, and candy bar may all meet some definitions of ultra-processing.
Protein, fiber, added sugar, calorie density, and the overall diet still matter.
The goal doesn't need to be avoiding everything that comes in a package. A more practical approach is to keep highly processed foods from becoming the foundation of the diet.
What Should We Eat Instead?
Lustig's answer is straightforward: make minimally processed foods the default.
That can include vegetables, whole fruits, fish, meat, eggs, nuts and seeds, healthy fats, fiber-rich foods, and minimally processed dairy.
The exact diet can vary. Someone can follow a Mediterranean diet, a lower-carbohydrate diet, or another whole-food approach while following the same principle.
What I Take From Lustig
I don't think we need to decide that every processed food is dangerous, nor do we need to eat a perfect diet.
The more useful lesson is about proportion. If most of what we eat consists of recognizable, minimally processed foods, an occasional highly processed food probably isn't the central problem.
Instead of constantly asking:
Is fat bad? Are carbohydrates bad? How many calories are in this?
we can begin with another question:
How much has this food been altered from its original form?
For me, Lustig's most useful advice can be reduced to three words:
Eat real food.
Learn More
Metabolical:The Lure and the Lies of Processed Food, Nutrition, and Modern Medicine
Dr. Lustig's book about processed food, nutrition, metabolic health, and the modern food system.
Videos
You May Never Eat Sugar Again After Watching This! - 18 Minutes
A short introduction to Lustig's concerns about sugar and metabolic disease.
Sugar, Metabolic Syndrome, and Cancer - 58 Minutes
Dr. Lustig discusses sugar metabolism, insulin resistance, metabolic syndrome, and their possible connections with cancer.
The True Purpose of Nutrition - 1 Hour 11 Minutes
A broader discussion of food, metabolism, and what nutrition is supposed to accomplish.
Ultra-Processed Foods Fueling Neurological Problems - 34 Minutes
A discussion of ultra-processed foods and their possible relationship to brain and neurological health.