Sugar: The Bitter Truth

Dr. Robert H Lustig MD, a professor of Pediatrics at UC San Francisco, lectured on why refined sugars, particularly fructose, along with not enough fiber, contribute significantly to our obesity epidemic. It is fascinating yet haunting, and I highly recommend it to anyone. It’s basically what inspired me to do this project.

It’s called “Sugar: The Bitter Truth” and it is available on YouTube.  Dr. Lustig also has a seven-part miniseries called “The Skinny On Obesity”, which I hope to watch soon also. It looks like it is very informative! Anyways, here is the run down of what I got from his lecture:

He begins his lecture with a couple surprising facts.

  • The USDA regulates everything  (trans fats, saturated fats, calories, sodium, etc.)…except for sugar. Considering that it’s a big part of the obesity epidemic, there is clearly something wrong with the system.
  • If a person drank one soda a day, that would be equivalent to adding about 15.5 pounds of fat each year. If each soda is 15o calories, multiply that by 365, and divide it by 3500 (the amount of calories in a pound of human body fat), you get about 15.64.
  • The average American consumes about 141 lbs of sugars per year.
  • If you walked down the bread isle, out of 32 refined breads, only 1 doesn’t contain some sort of added sugar

Then, he moves onto a bit of history, in which he explains why consumers today are surrounded by so many unhealthy, high-sugar options. Basically,

  • In 1973, Nixon decided to subsidize food, to make it cheaper to the American. Not a bad idea, but it had profound implications, as we all know today.
  • The invention of high fructose corn syrup in the 1960’s made it easier for manufacturers to put sugar in their products since it was substantially cheaper.
  • At around that same time, the USDA made an order to reduce fat consumption from 40% of our diet to 30% because there were studies that showed it caused bad cholesterol and strokes, which is also true.

That third point is important, because, surprisingly, the food industry did comply with that order and brought the fat content of it’s food down. But, without the fat in processed foods, they became basically tasteless. Processed foods in general are pretty tasteless pieces of cardboard, so they would always need some component to compensate for the taste of the lost fat, and that came from massive amounts of added sugar. However, sugar turned out to be even worse for Americans.

There are two big types of sugar, says Lustig. Glucose and Fructose. The former is a natural sugar that humans have been burning for energy for thousands of years. The latter however, is not naturally metabolized, and is sent directly to the liver. An article by Susan Beck from Pediatrics Consultant Live explains the difference and effects pretty well.

Fructose metabolized like fat – just as alcohol is. Dr Lustig did a masterful job of explaining the many ways in which fructose metabolism differs from human metabolism of glucose. When glucose is metabolized, it promotes a nice negative feedback pathway involving the liver, pancreas, and brain. The end result is that, through the suppression of ghrelin, the appetite for more glucose is suppressed and glucose consumption is kept in check. Insulin performs efficiently, and energy is stored in a usable form.

Fructose metabolism takes a very different form. In fact, it is metabolized by the liver in many ways just like a fat – and 30% of fructose actually ends up as fat. By-products of fructose metabolism include uric acid (which causes hypertension), very low-density lipoprotein (VLDL) cholesterol and triglycerides (which contribute to dyslipidemia), and free fatty acids (which lead to insulin resistance). These are all components of the metabolic syndrome. In addition, fructose leads to leptin resistance, thereby setting up a positive feedback pathway in which continuous consumption is promoted. (Dr. Lustig pointed out that these problems are all minimized when fructose is consumed in the form of whole fruit, since whole fruit always contains significant amounts of fiber , and fiber works to counteract the effects of fructose in a variety of ways. “When G-d made the poison, he packaged it with the antidote,” he said.
Dr Lustig noted that fructose metabolism also is strikingly similar to the way in which ethanol is metabolized. He made the graphic point that a 150-calorie can of soda and a 150-calorie beer both lead to 90 calories reaching the liver, and that both result in the toxic by-products of VLDL cholesterol and excess free fatty acids. Excess alcohol consumption and excess fructose consumption also result in many of the same health problems. Both cause hypertension, dyslipidemia, insulin resistance, and fatty liver disease.
Even more frightening, Lustig says that the earlier one is exposed to sugar, the more they will crave it later in life. For example, infant formulas are highly sweetened, containing large amounts of lactose, fructose, and glucose.
There are four points that Lustig summarizes with, or his bottom lines:
  1. Fructose is a carb
  2. Fructose metabolizes like a fat and is in fact, high fat
  3. Fructose is a toxin
  4. The FDA labels fructose as a GRAS (generally regarded as safe) food, however, that label isn’t based off of any solid research.
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