---

Q: Could you start by introducing yourself?
A: I am Dr. Robert Lustig, a pediatric neuroendocrinologist. This means I study how the brain controls hormones and how hormones influence neuroscience. My main focus has been understanding why so many people today are obese and sick—and figuring out what we can do to address these problems.

Q: In your opinion, how can we stop the obesity and diabetes epidemic?
A: The first thing to understand is that obesity is not simply the result of two behaviors: overeating and lack of exercise. Many people think this because they believe obesity adheres to the first law of thermodynamics: energy in equals energy out. In simple terms, they believe that if you eat it, you’d better burn it, or you’ll store it as fat. According to this logic, weight gain is a matter of personal responsibility. If you’re overweight, it must be your fault, and the only solution is diet and exercise. This thinking also leads to the belief that any calorie can be part of a balanced diet, whether it comes from a Coca-Cola or a kumquat.

But my research has shown that this is not the case. A calorie is not just a calorie. While it’s true that a calorie is a unit of energy—the amount needed to raise the temperature of one gram of water by one degree Celsius—what really matters is how different calories are metabolized in the body.

Calories from ultra-processed foods are particularly problematic. Even if the nutrients in ultra-processed and unprocessed foods are the same, the processed versions will make you gain weight, eat more, and burn less energy. This is because ultra-processed foods have specific defects:

1. Too much sugar, which directly causes metabolic diseases.
2. Too little fiber, which means sugar enters the bloodstream more quickly, causing damage.
3. A lack of anti-inflammatory fatty acids like omega-3s.
4. Harmful emulsifiers, which damage the gut lining and cause systemic inflammation.

These factors combined are the main defects in our current food supply. Numerous studies, including my own, have shown that when people eliminate ultra-processed foods from their diet, their markers for longevity improve, and the pathogenic processes reverse. In short, it’s our food—not just our behavior—that’s the root of the problem.

Q: Many people want to live longer. Where do you think the focus should be—lifespan or healthspan?
A: You cannot fix lifespan without first fixing healthspan. In other words, you can’t improve how long you live without addressing the health problems that cause premature death. Right now, there are eight key pathologies driving aging:

1. Glycation: The binding of glucose or fructose molecules to proteins, making them less flexible and increasing cell death.
2. Oxidative stress: Reactive oxygen species damage lipids and proteins, leading to cellular injury.
3. Mitochondrial dysfunction: Impaired cellular energy production.
4. Membrane instability: Weak cellular membranes that lead to cell injury.
5. Inflammation: Often originating in the gut, causing systemic damage.
6. Methylation: Changes in DNA expression that contribute to disease.
7. Insuline resistance
8. Autophagy failure: The inability of cells to clear out waste, which impairs function.

These processes happen in all of us, but their speed determines how long we live. The faster they occur, the quicker we age. The slower they occur, the longer we live.

Bad food accelerates all eight of these pathologies. While exercise can help with some of them, it doesn’t address all of them. For example, glycation, oxidative stress, membrane instability, and methylation are not improved by exercise. This is why you cannot outrun a bad diet.

Q: If we need to focus on diet, what steps should be taken to improve our food system?
A: Ultimately, you have a choice: pay the farmer or pay the doctor. Would you rather invest in healthy food and stay well or save money on food only to spend it on healthcare later? Unfortunately, our current food paradigm is driven by profit, not health.

Ultra-processed foods have been a public health disaster. They not only harm individual health but also contribute to societal, mental, and environmental problems. Chronic metabolic diseases cost the world $11 trillion annually, while environmental damage from producing and consuming ultra-processed food costs $7 trillion. Add in $1 trillion in lost productivity, and the total cost is $19 trillion per year—far outweighing the $9 trillion profit of the global food industry.

We need to make it clear that our food system is unsustainable and that change is urgent.

Q: Is today’s food really worse than ever?
A: Yes. In the U.S., we effectively pay an “eight-year longevity tax” because of our food. While the average lifespan in Japan is 86 years, it’s only 78 in America. This gap isn’t due to differences in healthcare but in diet.

If you’re obese, that longevity tax increases to 15 years. And if you have metabolic syndrome—conditions like diabetes, cardiovascular disease, cancer, dementia, or fatty liver disease—you’re paying a 20-year longevity tax. The choice is clear: a few less dollars in your pocket for better food, or decades lost to poor health.

Q: With the global population growing, can we sustainably produce enough healthy food?
A: By 2050, there will be 10 billion people on Earth. Producing enough food sustainably will be a major challenge. Instead of focusing solely on producing more food, we need to make processed food healthier.

Healthy food, processed or not, must adhere to three principles:

1. Protect the liver.
2. Feed the gut.
3. Support the brain.

I’ve worked with companies to re-engineer their products according to these principles. For example, we’ve added fibers that form a 3D matrix in the stomach. This matrix traps sugars and refined carbohydrates, preventing early absorption and allowing the gut bacteria to process them, which generates anti-inflammatory compounds. These innovations show that it’s possible to improve processed foods.

Q: Dementia is a major issue. How does diet affect brain health?
A: Dementia rates are skyrocketing, and food plays a significant role. The Lancet Commission published a major report on dementia but didn’t mention food even once. However, research shows that eliminating sugar, increasing omega-3 intake, and adding B vitamins can reduce dementia risk by 60%.

Small fish like sardines, anchovies, and mackerel are excellent sources of omega-3s with low levels of toxins. Supplements made from algae are another great option.

Q: Thank you for this enlightening conversation, Dr. Lustig.
A: Thank you. It was a pleasure discussing these important topics.

---