It seems to be human nature to want to find ONE SOLUTION to complex problems. Obesity is no different. Every few years something new is blamed as THE CAUSE OF OBESITY. At least one of those is high fructose corn syrup (HFCS). Like others before, it has been blamed as the cause of obesity, diabetes/The Metabolic Syndrome, health problems and the breakdown of the nuclear family.
A lot of this idea started with research by Bray who CORRELATED an increase in the intake of high fructose corn syrup with increasing rates of obesity. Much of this started with a 2004 paper by Bray where he correlated changes in HFCS intake with changes in obesity, suggesting that it was the increase in HFCS intake that was driving obesity. This was taken, as usual, far out of context into the popular realm of magazines, newspapers and tv soundbites.
Suddenly high fructose corn syrup was THE enemy.
Nowhere is this more prevalent than in the athletic/bodybuilding and fat loss arena where people are simply losing their ever-loving minds over anything with HFCS. Any food that dare list high fructose corn syrup on its label (even if the total quantity is obviously miniscule) is immediately deemed to be evil, a destroyer of not only one’s physique but a corrupter of children, a direct line to Satan himself. Ok, maybe I’m exaggerating but not by much.
But is this actually the case? Is HFCS in and of itself the problem here?
To examine the issue, I want to look at the paper
High Fructose Corn Syrup: What It is and What it Ain’t
This paper, in the aggregate, addresses this idea, by looking at the hypothesis that somehow HFCS is uniquely obesity or health-problem causing beyond simply being a source of calories. The author states that several assumptions must be found to be true to accept this idea as fact. They are:
- HFCS and sucrose are significantly different
- HFCS must be uniquely obesity-promoting
- HFCS must be predictive of US obesity
- HFCS must be predictive of global obesity
- Eliminating HFCS from the food supply must significantly reduce obesity
I won’t detail in full every one of his arguments. But the punch line of course is that none of these actually turn out to be true. Yes, HFCS and foods containing them often contribute a large number of calories to the diet and clearly that alone causes problems. But there is nothing special about HFCS to warrant the fear about it that many seem to have developed.
What is HFCS and is it Really Different than Sucrose?
Historically, HFCS was developed back in the 50’s as an alternative to cane sugar for food preparations. The reasons why HFCS is superior for foods than cane sugar isn’t really that relevant. Sufficed to say that HFCS is more stable and has replaced your basic cane sugar/sucrose in a lot of foods.
Now, a lot of the silliness, especially in the fitness world about HFCS probably comes out of two factors.
The first is a generally anti-fructose, anti-fruit idea that started about 30 years ago with John Parillo. For absolutely absurd reasons, fruit is often considered forbidden during a contest diet. Nevermind that it helps a LOT of people with hunger (liver glycogen status is one of many signals to the brain) and seems to do something good for thyroid status for many people. Parillo said it slowed down fat loss or even caused fat gain and the lore remains.
The second is a general confusion about what HFCS actually is, the problem is with the name, the “high fructose” part of it suggests to people that HFCS is much higher in fructose content that it actually is. However this is not the case as the chart below shows. The percentage of either fructose or glucose is shown for each of the types of sugars.
As the chart clearly shows, HFCS-42 is only 42% fructose which is a LOWER fructose content than straight sucrose, invert sugar or honey (often considered “healthier” at least in hippie/health food subcultures.
In contrast, HFCS-55 is 55% fructose meaning it contains 5% more fructose than the other sugars. To put this in perspective
- 50 grams of HFCS 42 would contain 21 grams of fructose
- 50 grams of sucrose, invert sugar or honey would contain 25 grams of fructose
- 50 grams of HFCS 55 would contain 27.5 grams of fructose
That’s a whopping 2.5 grams more fructose than straight table sugar.
It’s worth noting that there are products such as HFCS-80 and 90 which contain 80 and 90% fructose but they aren’t used widely commercially so I won’t consider them further.
The point being that despite its name, high fructose corn syrup is not functionally higher in fructose than other sugars. The “high fructose” moniker is simply a very poor choice of names that has led to widespread confusion.
Correlation is not Causation
The initial “data” suggesting that HFCS was responsible for obesity was correlational in nature. That is, increases in HFCS intake seemed to track. The thing is that correlation is not causation. Lots of silly things correlate with one another which have nothing to do with each other.
Which isn’t to say that the increasing intake of a high-calorie sugar compound isn’t likely to be a contributor to obesity. The question is whether HFCS is somehow unique in its contribution outside of the calorie content.
As well it’s not as if an increase in HFCS content was the ONLY change occurring in society during the time period it seemed to track with obesity. It was one change of many. Despite Bray’s assertion that increases in HFCS correlates with increases in obesity, the paper points out that he looked at the relationship in isolation.
During the time that HFCS intake was going up, daily food intake was also increasing, by about 500 calories per day from 1980 to the year 2000. That alone would predict increased rates of obesity regardless of HFCS per se.
Additionally, intake data shows that total sugar intake did not increase over that time frame. As HFCS intake was going up, sucrose intake was going down. Rather, what people were eating more of were grains and dietary fat. There is simply no basis to conclude that increasing HFCS intake has any correlation with rising rates of obesity per se.
Is High Fructose Corn Syrup Sweeter than Sucrose
It’s often claimed that HFCS is sweeter than sucrose, the logic being that the sweet flavor will increase intake. But this is also untrue. While pure crystalline fructose IS sweeter than sucrose, HFCS is identical in sweetness. Increasing use of HFCS in the US food supply did not increase the relative sweetness of those foods.
Note: pure fructose is rarely consumed outside of hippy subcultures who believe it’s healthier. As importantly, consuming LARGE amount of fructose causes stomach upset. Part of the entire HFCS debate went off the rails by focusing on the fructose itself. Zillions of studies giving pure fructose were done, often using absurd amounts which have no basis in real life. But people simply don’t eat pure fructose by and large.
Importantly, both high fructose corn syrup and sucrose contain 4 calories/gram. In that sucrose appears to have been swapped out for HFCS in a more or less 1:1 ratio, there is no reason to believe that HFCS intake is increasing caloric intake outside of simply being a source of calories.
Does the Metabolism/Absorption of HFCS Differ from Sucrose?
Finally, the paper looks at the issue of absorption and metabolism of sucrose vs. HFCS. While fructose is metabolized differently than glucose (in terms of the transporters used and how it is handled in the liver), keep in mind that HFCS is only about half-fructose, just like sucrose. Fructose malabsorption is a problem, mind you, but only when large amounts of fructose by-itself is consumed (as above this is rare), this does not apply to HFCS.
Quoting from the paper:
Sucrose, HFCS, invert sugar, honey an many fruits and juices deliver the same sugars in the same ratios to the same tissues within the same time frame to the same metabolic pathways. Thus…it makes essentially no metabolic difference which one is used.
So, again, while HFCS is certainly a source of calories (and many HFCS containing foods are easily overconsumed), there is nothing special about HFCS that makes it uniquely problematic. Fruit juice or a sucrose containing soda would function identically in the body to a HFCS containing drink.
Is HFCS Uniquely Obesity Promoting?
At the start of this article, I gave a list of requirements that would have to be met to show that HFCS is UNIQUELY obesity causing compared to other sugars. Simply, they have not been met.
So what’s going on? As I noted above, much of the focus with HFCS has been on the fructose component and a lot of very stupid studies have been done on the topic.
One that is making the rounds now showed that feeding rats a 60% fructose diet for 6 months caused leptin resistance. But let’s reality check this. First and foremost, a human on 3000 calories per day consuming 60% as pure fructose would be consuming 450 grams per day. Every day. For six straight months (which is about the equivalent to several years in human time). Yeah, I won’t disagree that 450 grams of sugar per day would be unhealthy. But fructose is not the problem here: the 450 grams of sugar per day is.
To the above I’d add: ignoring the fact that rat studies are irrelevant, the study I linked actually did 6 months of pure fructose feeding before switching the rats to a high-fat diet. When they were switched to the high-fat diet they gained fat. But they actually gained NO fat on the high fructose diet. The conclusion that HFCS causes fat gain and fat doesn’t was actually contradicted by the paper itself. Something the idiots talking about it missed. Again, you’re not a rat so who cares.
Let’s further reality check it, the issue here is not pure fructose but HFCS which is only about half fructose. To consume that same 60% pure fructose diet would mean a diet of 120% HFCS. Wait, huh? By that I mean someone would have to consume 3600 calories (20% over maintenance) to get that much fructose. I think you can see that this is idiotic.
As the paper states:
A pure fructose diet is surely a poor model for HFCS, because HFCS has equivalent amounts of glucose. Because no one would eat a pure fructose diet, such experimentation must be recognized as highly artificial and highly prejudicial and not at all appropriate to HFCS.
Rather, diets examining sucrose intake make a much more appropriate model for HFCS. Not much has been done comparing HFCS to sucrose but what has been shows no metabolic difference between the two. And in a physiological, biochemical and nutritional sense, this is to be expected. HFCS and sucrose are essentially identical. And the body treats them as such (though for some hilarity read some of the idiot level comments on this article).
Does HFCS Intake Predict Either US or Global Obesity?
In a word, no. While Bray’s original analysis suggested a correlation between increasing HFCS intake and US obesity, that relationship no longer holds. HFCS intake has been decreasing in the past year yet obesity continues to increase. Not only is there no biological reason to expect HFCS to uniquely cause obesity, it’s no longer even correlational with it.
Moving to the global arena, there is simply no relationship between HFCS intake and obesity rates with the two countries showing the highest rates of obesity showing the lowest intake of HFCS.
The correlation never mattered to begin with. Now it doesn’t even exist.
Will Eliminating HFCS from the Food Supply Affect Obesity?
You can probably guess the answer which is no. Given that HFCS and sucrose are nearly identical in composition, given that HFCS has replaced sucrose intake in the human diet over the past 30 years, given that they are handled metabolically identically, given that they have the identical caloric value, replacing HFCS with sucrose will simply have no effect on anything. Except perhaps to raise prices since sucrose is higher than HFCS.
What Do We Do with this Information?
Now, since I know some people will mis-interpret this piece, I want to be clear: the paper I examined is NOT saying that people can or should be consuming HFCS in massive amounts. Many HFCS containing foods contain massive numbers of calories. The problem isn’t the HFCS per se, it’s the calorie content.
Of some interest, a large amount of HFCS is consumed in sweetened soda. This is interesting because, unlike foods, beverages are not well compensated for by the body. By that I mean that increasing calorie content in fluids doesn’t cause the body to reduce food intake at other times. When you add calorie containing drinks (except for milk) to the diet, you increase calorie content.
So IF HFCS has any direct effect on obesity, this is it. But it has nothing to do with HFCS and everything to do with the liquid form. Sucrose containing soda or fruit juice has an identical effect.
I’d add more to this. Obesity is multi-factorial and many eating habits tend to cluster together. I want everyone reading this to do a little thought experiment: when you have known someone who consumes a LOT of sugary soda, what does the rest of their lifestyle look like?
If you said “Well they are usually inactive and eat a lot of high-calorie, high-fat, high-sugar foods” you’re going to be correct more often than not.
Is HFCS the issue or is it the fact that people who consume lots of HFCS containing sodas have an overall poor diet and lifestyle the issue?
What I’m getting at with this research review is that the near insane over-reaction and concern to any food containing any amount of HFCS among certain groups. Folks on forums are throwing out the baby with the bathwater under the gross misunderstanding that HFCS per se is a unique evil which it clearly isn’t. Within the context of a calorically controlled diet, there is no reason to believe it will have any differential impact beyond every other sugar that has ever been used.
- Carbohydrates Part 1: Classification and Digestion
- A Short History of Beverages and How our Body Treats Them – Research Review
- A Primer on Dietary Carbohydrates – Part 2
- The Effect of Two Energy-Restricted Diets, a Low-Fructose Diet vs. a Moderate Natural Fructose Diet – Research Review
- A Primer on Dietary Carbohydrates – Part 1