By Dr. Mercola

What is the proper role of sugar in our society? It used to be a condiment; now it’s a diet staple. Mounting evidence clearly shows that refined sugar is a primary factor causing not just obesity, but also chronic disease.

According to Dr. Robert Lustig, Professor of Pediatric Endocrinology at the University of California, San Francisco (USCF), sugar acts as a chronic, dose-dependent liver toxin (poison) when consumed in excess.

You might recognize Dr. Lustig from one of the most popular YouTube videos on sugar that has over 5 million views. You might also have seen him on 60 Minutes, which ran a report on the dangers of sugar in 2012.

You might also have seen him sparring with Stephen Colbert or Bill Maher. Or you might know him from his book, Fat Chance.

Never before have humans consumed as much sugar as we do today, and the ramifications of this dietary change are quite clear. Fructose, found in most processed foods, is by far the worst form of sugar, causing the greatest amount of harm in the shortest amount of time.

For example, in one clinical trial, test subjects who consumed high fructose corn syrup (HFCS) developed higher risk factors for cardiovascular disease in just two weeks.

Chronic Disease Has Risen in Lockstep with Sugar Consumption

Historically, sugar was used as a condiment. As early as 1200 BC, India developed a process to extract cane juice, called khanda, which is where we got the word “candy” from.

"It was for nobility and it was hard to come by, until about year 1700, when the pot still allowed for mass production of refined sugar. It was still extraordinarily expensive until the middle of 18th -19th century," Dr. Lustig says.

"At that point, we started seeing it appearing in various venues. We started seeing the growth of American sugar industry in Louisiana, Texas, and Hawaii. That's when we started seeing chronic metabolic disease.

In fact, the very first demonstration of an increase in chronic metabolic disease was in 1924, when Hayden Emerson, the commissioner of health of New York City, noticed a seven-fold increase in diabetes rate in the [city’s] population.

Then in 1931, Dr. Paul Dudley White (cardiologist at Massachusetts General Hospital) called attention to the fact that we had an epidemic of heart disease.

Finally, in 1988, we learned about the advent of adolescent type 2 diabetes. These are the three seminal hallmarks of chronic metabolic disease pervading our population. It goes up in lockstep with our increase in per capita sugar consumption.”

The bottom line is that sugar used to be something we added to coffee and tea. We had full control over the amount we ate. Today, we consume about 20 times more sugar than our ancestors did, and we have very little control over the amount since it’s become a diet staple.

It’s now found in virtually every processed food you can think of. On average, sugar makes up 15 percent of total calories consumed (about 19.5 teaspoons per day), and your liver, which processes sugar, simply cannot handle that kind of load. When you overload your liver in this way, you inevitably end up with chronic metabolic disease.

"Basically, sugar is metabolized virtually identically to that of alcohol, and we are now seeing diseases in children that we never saw before, and they are alcohol-related diseases, like non-alcoholic fatty liver disease and type 2 diabetes.

Kids don’t drink alcohol but they certainly consume sugar, and that’s the point,” Dr. Lustig says. “Sugar is the alcohol of the child. And we are all overdosed.

We have gone beyond our limits and we are now evidencing a massive increase in chronic metabolic disease that is chewing through the health care resources of every developed and developing country on the planet, and this is unsustainable."

Insulin Resistance—A Hallmark of Metabolic Syndrome

According to Dr. Lustig, whatever organ becomes insulin resistant ends up manifesting its own chronic metabolic disease. For example, when you have insulin resistance of the liver, you end up with type 2 diabetes.

When you have insulin resistance of the brain, you end up with Alzheimer’s disease. Insulin resistance of the kidney leads to chronic renal disease, and so forth. All of these diseases are insulin resistant states. The question is what causes the insulin resistance in the first place?

"[W]e have some new data that we are very excited about, which demonstrate that if you overload the mitochondria, the little energy-burning factories within cells, in any given organ, you'll end up manifesting various forms of chronic metabolic disease," Dr. Lustig says.

“The chemical that overloads the mitochondria best is trans-fats. But the chemical that overloads the mitochondria next best is sugar. Trans fats and sugar pretty much characterize the processed food diet.”

In November 2013, the US Food and Drug Administration (FDA) removed trans fats from the Generally Recognized as Safe (GRAS) list. This is a step in the right direction. Unfortunately, instead of reverting back to healthy saturated fats like coconut oil, lard, and butter, trans fats have been replaced with other non-saturated vegetable oils, that when heated, produce toxic aldehydes which cause cellular damage.  

We may not realize the full ramifications of this switch until a decade or two down the line. Sugar, on the other hand, is going to be even more difficult to dislodge from the food system.

According to SugarScience.org, added sugars hide in 74 percent of processed foods under more than 60 different names.¹ And yet, getting rid of the excess sugar in processed food is exactly what needs to be done.

"As long as sugar is on that (GRAS) list, the food industry has license to use as much as it wants to in any given food stuff. So, sugar has become the biggest problem in our diet since the advent of trans fats," Dr. Lustig says. "Granted, there are many problems with processed food. There's too much of five things and too little of three things.

There's too much trans fats; too much omega-6 fatty acids (which are pro-inflammatory); too much branched-chain amino acids (which also overload your liver and cause chronic metabolic disease)... too much alcohol, and too much sugar.

On the too-little side, there's too little fiber, too few micronutrients, and too little omega-3 fatty acids, which are anti-inflammatory. Processed food has a zillion things wrong with it. Unfortunately, processed food is what we subsidize. Processed food is what we expect people to consume because of 1) expense and 2) shelf life. That’s making a fortune for the food industry, but it’s killing us.”

Is There a Safe Threshold for Sugar?

According to Dr. Lustig, trans fats are “without question consumable poison.” But is sugar as bad or worse than trans fat? Dr. Lustig says no, it’s not worse, because while there is no threshold at which trans fats are safe, there may be a threshold below which sugar will not cause a problem. While there are individual differences, as a general rule the safety threshold for sugar appears to be around six to nine teaspoons (25-38 grams) of added sugar per day.

“That’s what the data suggest, because your liver does have the capacity to metabolize fructose, as long as the mitochondria don’t get overwhelmed,” Dr. Lustig says. “So as long as you keep it below the threshold, above which toxicity would occur, I think that, probably, sugar is okay.”

Whether or not you're insulin resistant will play a role, as insulin resistance generates hyperinsulinemia. Hyperinsulinemia means that there's more insulin at the fat cell, which means you'll shunt more energy into those fat cells because that's what insulin does. Insulin resistance is clearly associated with weight gain. But while many believe that insulin resistance is the result of weight gain, recent data argues against that notion, Dr. Lustig says. Instead, the data shows that insulin is what drives the weight gain.

When your liver turns excess sugar into liver fat and becomes insulin resistant, that generates hyperinsulinemia, and hyperinsulinemia drives energy storage into body fat.

Currently, about two-thirds of the American population is overweight. About one-quarter to one-third is diabetic or prediabetic, and another quarter of the population is hypertensive. Many also have high serum triglycerides.  Insulin resistance is a component of all of these health issues. According to Dr. Lustig, the data shows that at least 50 percent of Americans have some form of insulin resistance—whether you’re overweight or not—and that is what’s driving our seemingly out-of-control disease statistics.

Metabolic Disease in America

As Dr. Lustig notes, if you were to do a Venn diagram^2,3 of the United States population, you'd have 240 million adults in that diagram, divided into two circles. One circle would be about twice as big as the other: the obese population forming a smaller circle of about 30 percent, and the non-obese population forming a larger circle of about 70 percent. Eighty percent (57 million people) of the obese population is metabolically ill. They have insulin resistance that manifests itself in a myriad of ways, including type 2 diabetes, hypertension, dyslipidemia, heart disease, cancer, and dementia.

"The standard mantra is, 'If they would just diet and exercise, they wouldn't be obese and we could solve this problem,'" Dr. Lustig says. "This is patently untrue. It is true that 80 percent of the obese population is metabolically ill. But that means that 20 percent of the obese population is not. They're metabolically healthy. They are called metabolically healthy obese. They will live a completely normal life, die at a completely normal age, and not cost the taxpayer a dime. They are just fat. They're not contributing to our runaway medical train, as it were."

Conversely, it turns out that of the 70 percent that are of normal weight (168 million people), 40 percent of them (67 million people) have insulin resistance on lab testing, and they manifest aspects of the metabolic syndrome as well. They too get type 2 diabetes, hypertension, dyslipidemia, cardiovascular disease, cancer, and dementia. The prevalence of metabolic disease among normal weight people is not as great as among obese people—40 percent versus 80 percent—but they do get ill and there are far more people in this group.

“When you do the math, there are more thin sick people than there are fat sick people,” Dr. Lustig says.  “The thin sick people are actually costing more, and when you do the math on the two together, the sick population is 124 million—that’s more than half of the US adult population. It turns out the thin sick people are costing us more...

And you can't attribute this to gluttony and sloth or diet and [lack of] exercise, because they're normal weight. If it's not about behavior, then there's only one other option: it must be about exposure. This is an exposure that obese people are exposed to and it's an exposure that even normal weight people are exposed to. That is called the Western diet. The Western diet is replete with sugar. Sugar is mechanistically the thing that drives this insulin resistance."

How Do You Resolve Insulin Resistance?

The answer can be summarized in two words: real food. According to Dr. Lustig, the overwhelming majority, 60-70 percent of the patients seen in his clinic are there as a result of their processed food diet.

"What we have to do is we have to move them back [to real food], and what we do is we explain what real food is. A lot of kids don't even know what real food is. A lot of kids think that fruit flavored yogurt is real food; it is not. We explain that yogurt is sour milk [it's not sweet]... So if you want yogurt, have plain yogurt and throw whole fruit in, just like what Europeans do. That's called real food."

Intermittent fasting may be another way to address insulin resistance. Although Dr. Lustig doesn’t think most people have to go this far, he believes it can work for some. When you fast, your liver burns off the available liver fat. So you’re temporarily depleting your liver fat stores, restoring metabolic stability to your liver and improving hepatic insulin sensitivity. That said, he believes that the long-term answer for most people lies simply in eating real food.

"I think you can do this rationally, by eating properly all the way through the week rather than having to do intermittent fasting. I think, ultimately, the goal is get the liver fat down. And since the cause of the liver fat is dietary sugar, via the process of De novo lipogenesis... once you get rid of the sugar, the liver fat will go down, and we have data that supports that, both in adults and in children... I think, ultimately, what you have to do is get the liver fat down. Will intermittent fasting do that? Yes, it will. But will eating properly do that too? It does it even better," he says.

"What we tell people are these very simple rules, all of which are evidence-based: get rid of every sugared beverage in the house. Then, eat your carbohydrate with fiber. Whole food is okay because the fiber mitigates the negative effects of the fructose on hepatic metabolism, because it reduces the rate of absorption... We don't tell people they can't eat sugar. But they have to eat sugar in a form that nature provided it, and it's called whole fruit."

The Importance of Exercise

Exercise is also an important component. Interestingly, Dr. Lustig notes that exercise works not by promoting weight loss; rather its benefits are related to the fact that exercise promotes muscle gain. It may be a fine distinction, but one worth noting nonetheless. There is a transcription factor known as Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), which is involved in mitochondrial biogenesis. When you turn up PGC-1α, you make more mitochondria. Increasing your sympathetic muscle tone. This is what exercise does, it turns on PGC-1α. So, in short, exercise increases muscle mass, which increases mitochondria, and this in turn improves insulin sensitivity.

"Every doctor who tells their patient, 'Well, if you'd exercise, you'd lose weight.' Given what we know now, this statement is tantamount to malpractice, because it isn’t true. There are no studies that show [exercise leads to weight loss]. Yet, exercise is the single best thing you can do for yourself and we should be promoting it, but we have to explain to patients what the outcome variable they should be looking at is. And the outcome variable is belt size [waist size], because they will reduce their visceral fat. They will lose inches, not pounds. And losing inches means improved metabolic health," Dr. Lustig explains.

Research Proves Causation—Sugar Definitely Increases Risk for Disease

At present, there are 15 agencies and 51 separate agreements controlling food regulatory activities in the US, and according to Dr. Lustig, “no one knows what the other hand is doing, and the food industry takes complete advantage of this.” Dr. Lustig and many others are pushing for a national food policy. He also insists that “it’s time for us to take food back as a mode of therapy.” And if food is medicine, doctors really must be taught a thing or two about nutrition...

“We have the data. We don’t have correlation anymore. Now, we have causation. We have causation for sugar and obesity (although sugar is not the only cause). We have causation for sugar and diabetes, for heart disease, and for fatty liver disease... We now have causation. It’s time to do something about it.”

For example, a paper by Yang, et al, published in JAMA Internal Medicine last year looked at consumption of added sugar over two decades, as a percentage of total calories, concluding that it significantly contributed to cardiovascular deaths. People who consumed 30 percent of their daily calories as added sugar (like many teenagers are) had a four-fold greater risk of dying from heart disease.

"If you think we got a problem now, wait until our teenagers hit heart disease age; things are really going to be even worse shortly," he notes. "Food should confer wellness, not illness, and it used to. But then, the food industry got involved. And now it confers illness, not wellness. We have to take back our food."

To counter the propaganda provided by profit-driven industry interests, dozens of scientists at three American universities—including Dr. Lustig—have created a new educational website called SugarScience.org,⁴ aimed at making independent research available to the public. To learn more about what the science really says about sugar, I highly recommend browsing through the site.