Is it really just fructose that’s making us fat and unhealthy?
In an effort to keep things understandable by the average person visiting my blog, I like to keep things as simple as they can possibly be. You and I both know not everything is so black and white, but the trick is to get people at least thinking about a subject and hopefully digging deeper on their own to learn even more about it. That’s the essence of learning–get armed with a little truth and then investigate it further and further until comprehension takes place.
One such simplistic subject you often see me blog about is sugar. Yes, there’s that sweet-tasting white stuff known as sucrose, or table sugar, that millions of Americans put in their food and drinks each day without any regard for what it is doing to their bodies. An equally if not MORE harmful sugar is the evil high-fructose corn syrup that is showing up in about 90 percent of packaged foods these days. Food manufacturers made the switch from sucrose to fructose in the 1970s and our weight and health has suffered ever since.
That’s why I think it is awesome to see books coming out from major publishers blowing the horn on the harmful impact that sugar, both in the form of sucrose and fructose, is having on us. One such book that looked to be promising was the April 2008 release from Rodale called The Sugar Fix: The High-Fructose Fallout That Is Making You Fat and Sick by Dr. Richard Johnson. On face value, it sounds like a good book for people who are livin’ la vida low-carb to read. We pretty much all agree fructose is bad news and should be avoided.
Questions linger about what role sucrose and even sugar that is produced by starchy carbohydrates play in obesity and disease. Dr. Johnson apparently does not address this in his book and that had one of my readers very concerned. Although I have not yet read this book (but would like to!), this very concerned reader says now he’s confused.
After he read Gary Taubes’ masterpiece Good Calories Bad Calories where insulin was identified as the source of obesity and disease, not just fructose, he’s left scratching his head about what the truth is. In his e-mail to me, the reader asked if I would forward on his questions to Taubes for a response. Below you will see both the reader’s original e-mail to me and Gary Taubes’ reply:
Hey Jimmy, I know you must get a million emails a day, but here’s one more! I just finished reading a new book called The Sugar Fix.
And now I’m REALLY confused. I thought it would be a low-carb message, but it ended up being a low-FRUCTOSE message with the “calorie is a calorie” theory underpinning it. The author Richard Johnson, who is a medical researcher and a kidney transplant doctor (so he should know his stuff), claims that it is only the fructose in our diets that makes us fat and sick.
Following his logic, because sucrose is half fructose and high-fructose corn syrup (HFCS) contains a lot of fructose, all we need to do to be healthy and lose weight is cut out the fructose in our diets. Practically, of course, this means cutting out all drinks sweetened with sugar and HFCS, and cutting down on table sugar, honey, sweet desserts, etc. What really confuses me is that he claims that starch is not a problem.
He says in this book that insulin resistance is caused by FRUCTOSE, not glucose, and that glucose alone causes insulin to spike, but in the absence of fructose, it will not influence insulin resistance in the slightest. So according to this book, if you have your fructose under control (including fruit only in moderation), then you can still enjoy potatoes, pasta and breads because glucose from starch is not a problem.
Now, I’m going through Good Calories Bad Calories for a third time and Gary Taubes argues convincingly that INSULIN is the problem and leads to weight gain and sickness. You see why I’m confused? The author of The Sugar Fix quotes all the studies, is a researcher himself, and now I don’t know WHAT to think.
I thought you would find this interesting, but the real reason I’m telling you all this is that I’m hoping you might pass this note on to Gary Taubes. I would LOVE to hear from him on this, and I know you are in contact with him. His book has been extremely influential in my life, but now I’m having some doubts. THANKS!
And now here is what Gary Taubes had to say in response:
I interviewed Richard Johnson, the author of The Sugar Fix, for my book and have spoken to him a lot since his book came out. He is now trying to get a paper published arguing that fructose and thus sugar and HFCS are the environmental causes of diabetes and metabolic syndrome.
He only read my book after The Sugar Fix was published, so the argument that obesity is not caused by excess calories never made it into his book. That said, it still isn’t in his paper either, so he either doesn’t understand it fully or doesn’t buy it, which is fair enough. Although Dr. Johnson gives my book a very complimentary acknowledgment in the paper he’s trying to get published, I still think he labors under one of the problems I suggest is endemic in the medical research community: that he focuses too tightly on the subject of his own research and doesn’t look far enough outside of it to see what other factors might be involved.
Dr. Johnson does talk about the ability of fructose to stimulate fat synthesis in the liver and, at least indirectly, on its ability in the long term to cause insulin resistance, which, if I’m right, would still be the fundamental cause of weight gain. He’s primarily interested in the ability of fructose to elevate uric acid levels, which could be a causal agent, as well, in causing metabolic disorders in heart disease, obesity and diabetes.
I didn’t get into this in the book because the literature is very sparse and the book was already too long and technical. The fundamental problem here is differentiating between the effect of excess calories and the effect of the nutrient itself on fat deposition, thus allowing for the consumption of excess calories. Dr. Johnson argues that its not possible to induce insulin resistance in animal models by feeding them glucose alone–starches–and can only be done by giving them fructose. Or that it happens far more quickly with fructose than glucose alone. That may be true.
As I say in Good Calories Bad Calories, there is reasonable evidence that sugar is the fundamental problem. But that hypothesis has to be rigorously tested. It’s virtually impossible to find populations that consume refined carbs but not sugars. And, indeed, most populations that are used as counter examples to the carb-insulin hypothesis are those that consumed virtually no sugar–the Japanese, Koreans, etc.
The counter-argument is the one that Peter Cleave made in the 1960s, which is where you can find a lot of extremely fat people who eat no sugar at all but drink a lot of beer, which is another kind of refined carb/sugar–in this case, maltose.
There are four questions here that are key, and I don’t think any can be answered definitively: 1) is fructose alone the problem? 2). Is it worse or particularly noxious, as I suggest in the book, when it’s packaged with glucose, as it is in sugar and HFCS? 3) Does this mean high-glycemic index carbohydrates–white flour and white rice, for instance–are relatively harmless if fructose and so sugar and HFCS is not in the diet? And once sugar and HFCS have caused, say, obesity, metabolic syndrome and diabetes, can you cure the problem only by removing the fructose, but not the glucose?
One possibility, for instance, is that fructose and glucose are needed to create chronically elevated insulin levels and so cause weight gain, metabolic syndrome, etc., but that once the process is initiated all easily digestible carbohydrates keep it going or make it worse. What’s needed is a research community that takes all these hypotheses seriously and then sets out to find out the answers.
One other point to keep in mind is that there are diets out there that limit fructose dramatically–the DASH diet, for instance, that’s now being pushed to treat hypertension. It’s got virtually no sugar in it, but is still relatively high-carb. It does reduce blood pressure, which would be expected. There’s no reason to believe, though, that it drops weight as dramatically as the Atkins diet can, and Atkins restricts all carbs.
So I think Dr. Johnson’s hypothesis is very interesting and potentially very valuable, if it further directs attention to the potential dangers of sugar and HFCS, but I also think it’s too narrow and misses the effect of other carbohydrates, which also elevate insulin levels. I hope all this helps.
What do you think about all of this? As Taubes states in his response, these are the kinds of questions that the research community should be all over taking a serious look at for the sake of finding the answers for people like my reader who are confused. Unfortunately, most people just look at sugar as sugar regardless of its form and consume it liberally without any regard for what they are doing to themselves. They’re freaked out by eating fat, but sugar has to be okay because it tastes so good.
When did our world turn upside down? I look forward to your comments!
