Whether you're munching on salty snacks or sugary treats, it's no news that any type of processed food isn't great for your waistline—especially if you're eating it in place of fresh fruits and vegetables or other healthy foods like legumes and nuts. However, what's even more concerning is processed foods' ability to wreak major havoc on your health later down the line.

In Metabolical, which recently debuted in bookstores everywhere, Robert H. Lustig, MD, MDL, a pediatric neuroendocrinologist, exposes the many ugly truths of our current food system and modern medicine. He dives into the depths of eight pathologies within cells that belie all chronic disease, arguing that drugs aren't an adequate solution for prevention or treatment. Instead, Lustig demonstrates how the food we eat is the real cure—and enemy—for non-communicable diseases.

Ultra-processed foods, such as potato chips, cured meats, cheeses, and candy bars, are often teeming with added sugars, partially hydrogenated oils, and nitrates. In Metabolical, a title that marries the workings of the body (metabolic) with that of mass-produced food, Big Pharma, and Big Government (diabolical), Lustig illustrates how all of the components found in processed foods can lead to conditions like type 2 diabetes, heart disease, and even cancer.

How can eating processed foods lead to cancer?
"Nitrates are turned in the intestine first into nitrites, then into nitrosoureas, which are known carcinogens and cause colon cancer," Lustig says in an interview with Eat This, Not That!.

Recent research has even suggested that nitrates—which are found in cured meats like pancetta, prosciutto, and salami, plus other processed meats like bacon, beef jerky, and sausages—may increase your risk of developing cardiovascular disease on their own.

"And refined carbohydrates lead to insulin release and insulin resistance," he says. "Insulin is a growth factor that makes cancer cells grow, and glucose is their primary fuel."

Some cancers, such as pancreatic cancer, feast on fructose (which makes up 50% of table sugar or sucrose), allowing them to become stronger and more harmful.

"So, while sugar is not a specific cause of cancer cell differentiation, it is a primary driver of cancer cell growth," Lustig adds.

How has mass food production ruined society's health over the past several decades?
Excluding 2020, if you were to examine causes of death over the past 50 years, you'd notice that they've changed dramatically from infectious diseases (like influenza) to chronic non-communicable diseases (such as heart disease, dementia, and cancer), Lustig says.

"These are the diseases of mitochondria. We now have the evidence for how ultra-processed foods—especially sugar, but also trans fats—interfere with mitochondria to cause these chronic diseases," he adds. "In other words, food has gone from providing health to causing disease.

The point is that it's not the food—it's what's been done to the food that makes it poisonous."

What should you do to improve your own metabolic function and avoid chronic and inflammatory diseases?
Lustig says the answer lies within three words: Eat real food. It's simple.

"Real food is anything that came out of the ground or any animal that ate what came out of the ground," he adds.

When an animal is fed something processed, a plant-based item has been stripped of nutrients and fiber (think whole wheat versus white bread), or chemicals are added to animals' feed or growing crops, the food can then become a threat to our health.

"We have a limited capacity to metabolize these chemicals, and we are way over our limit," Lustig says.

For more, be sure to check out the 26 Worst Habits Slowing Your Metabolism, Says Science.