a pair of links to ponder

This post is a summary of a lecture given by Dr. Robert Lustig, talking about fructose and the role it may be playing in the general weight gain the U.S. has seen over the last thirty years.

This post is a counter-argument to Lustig.

I don’t know for sure what to make of any of it, except that I do feel Lustig’s being a bit alarmist by calling fructose a “poison” and agitating for its regulation. I’m not a biochemist, so round about the part where tongodeon‘s post turns into wodges of acronyms and other specialized terms (i.e. the metabolisys grafs), I lose track of the argument. But I can comprehend the beginning and the end, and they told me two useful things.

First, I thought I was all virtuous because I’d almost completely eliminated soda from my diet, replacing it with fruit juice. Why? Well, I’d heard that high fructose corn syrup was bad. Whether Lustig is right or not about the problems of fructose (not just HFCS), it does seem to be true that getting my fructose from juice doesn’t really make as a big of a difference as I’d assumed. I’m still chugging the stuff in large quantities, and I trust Lustig is at least right about how my body metabolizes it. What the effect of that might be, seems to be the point under debate. Anyway, I’m going to experiment for a while with cutting back on fruit juice, too, and see what that does.

Second, the “exercise does not work by burning calories” paragraph was exactly what I needed to read, because it clarifies for me some things I’ve never understood. The math of burning calories never worked out in my head (because it doesn’t, really), so I appreciated seeing a brief catalogue of the other things exercise does, that can have an effect on weight. (Aside from all the non-weight-related benefits, of course, like strength and endurance and agility and so on.) In other words, now I know what “it raises your metabolism” actually means.

Anyway, if you happen to be a biochemist on the side, I’d be interested to hear what you think of Lustig’s arguments. Is fructose (whether consumed as HFCS or sucrose) that important? How about the connection with fiber? Or is this, as the second post argues, just the new “low fat” argument, another attempt to demonize one specific part of our diet while losing sight of the big picture?

0 Responses to “a pair of links to ponder”

  1. difrancis

    I think it’s very interesting. I don’t drink fruit juice, but sometimes use honey and agave nectar as a replacement for sugar. But the bit about how excercise works was very interesting, as was some of the other stuff. Definitely gives food for thought. I’ve been trying to reduce intake of HFCS in general and am glad I’ve done so.

    • Marie Brennan

      Did you see the bit about agave nectar toward the end of the first post?

      A lot of things lately have been saying you should avoid HFCS if possible, but this is the first analysis I’ve personally seen as to why.

      • difrancis

        yeah, I saw it. And me too on this being the first analysis I’ve seen as to why. I’ve switched a lot to tea, and trying to cut back the sugar in it gradually (actually splenda, but the word is that it isn’t so great either). I’m beginning to be glad I had gestational diabetes with my pregnancies because I ate a nearly perfect diet given what this said. So I didn’t start them off on a wrong foot. But some of what he was talking about may account for some of the shifts lately in my cholesterol and etc numbers. I’m working on losing weight because I do have a metabolic syndrome and it’s very difficult. But understanding some of the chemistry does help. And he sounds reasonable, if, like you a said, a little alarmist.

        • Marie Brennan

          I would love to see a good analysis of the artificial sweeteners out there. I don’t know what to make of them; I just know I don’t like most of them.

          • difrancis

            me too. I think Stevia is the one that is considered most natural and integrates best in the body. Because of the chlorine element to Splenda, there are concerns. And of course Nutrasweet and Aspartame are supposed to have issues. I’ve gone to using real butter because I don’t eat much and it’s more natural. I read a thing on fats the other day and omega 3s and 6s that was really interesting about the balance (or lack thereof) in our diet. There’s supposed to be a ratio. I wonder where I found that. It was really interesting. But most people are skewed to heavily to the omega 6s and that creates issues.

          • Marie Brennan

            I admit I’m knee-jerk dubious of anything that artificial, simply because we don’t have a couple million years of omnivorous eating to tell us they’re probably okay. I can’t help but think a few decades down the road it’s going to be the late 20th-early 21st century equivalent of lead poisoning, y’know? Even if that’s unfair.

          • difrancis

            me too. One nice thing about living in Montana is that we eat a lot of game meat and it’s a lot healthier. On the other hand, there’s no growing season and so veggies and fruit are always questionable.

            A friend was just telling me about this stuff called Palene that some 4H and FFA people are feeding their animals. It’s a natural steroid apparently. Makes me wonder if commercial outfits are using it and if so, I don’t want to be eating it. Blech. My sister just got chickens in the city she lives in. I almost think it’s a good idea. At least to know what’s going into my eggs.

            Too much artificial crap in all our food. I wish that wasn’t the case.

          • diatryma

            Splenda made one of my aunts crazy. She started putting it in her coffee, then things got weird, and she came pretty close to taking herself to a hospital before another aunt said maybe she should look it up… and lo, some people react to large amounts of Splenda by becoming crazy. It was, I am told, a great relief to just stop megadosing on the stuff with her coffee.

  2. unforth

    As I’m on rather an exercise and health kick, I was pretty interested in this. I see some serious problems, though, at least based on my own understandings of things. Interesting, the paragraph that THE most red flag “danger, danger” to me was the exercise paragraph – one that you found helpful. Now again, this is based on my understanding of things, so I might not have things straight, but from my understanding that paragraph is all wrong. Exercise does burn calories. Calories are the energy that your body uses to do things. When it says “you’d have to jog 20 minutes to burn off one chocolate chip cookie,” it’s first of all highly deceptive: jogging 20 minutes can mean almost anything (speed? distance? incline?), and there isn’t one iconic thing that IS a chocolate chip cookie. If I get chips-ahoy, they have 80 cal each or so, and I can burn that many calories by jogging just under a mile (which happens to take me about 9 minutes). (put another way, my body uses the equivalent of about 80 calories worth of exercise in order to generate the momentum necessary for me to jog for 9 minutes). If I go to Starbucks and get one of those enormous cookies, they have about 500 calories, and I’d have to jog for almost an hour to burn that off.

    Beyond that, though, the paragraph is just confusing and inaccurate. Exercise makes the TCP cycle go faster because you need the ENERGY thus produced in order to make your body do things, and calories are one way of expressing that energy. And while it’s true that exercise reduces both stress and appetite, this also completely ignores the important part that exercise builds muscle, and muscle takes more energy for your body to maintain at all times, and thus simply having more muscle burns more energy (and energy can essentially be said to equal calories) and thus the positive energy-burning effects of exercise are amplified. This is what is meant by a higher metabolism rate: it represents how much energy your body needs to simply function at all times. By being active, your body needs more energy all the time, which burns through more of what produces energy, and energy comes from your body processing what you consume.

    This, while perhaps not that clear, is my understanding of how this works.

    Another one that stuck out to me was the claim that high sugar diets are the same as high fat diets. This isn’t true. There are plenty of high fat things that don’t contain hardly any sugar (cheese, oil, and butter spring to mind). Meanwhile, here’s a quote from the wiki article on Fructose: “Triglycerides are incorporated into very low density lipoproteins (VLDL), which are released from the liver destined toward peripheral tissues for storage in both fat and muscle cells.” This is reference to all that chemistry. Lustig tries to say that Fructose metabolizes into fat, so it’s bad – but according to wiki (and I see no reason to doubt it on this point) that same substance builds our muscles. That means we need it.

    Also, as far as I can tell, he pretty much completely ignores the exercise question. He talks about people eating more, and what they are eating, but doesn’t at all discuss evidence that suggests that people are much less active than they used to be.

    The suggestion that the FDA doesn’t regulate fructose because of exports and corporate conspiracy is flat out completely absurd. To regulate fructose would be to tell people not to eat fruit. And how would this regulation be done? The suggestion that this one thing is the source of the evil is really absurd.

    • unforth

      All in all, I think that this is pretty much new “low fat” argument. All of these things, like the Atkins diet, suggest that there’s a magic bullet: change this one thing, and poof, it’ll be better! The key isn’t to change just one thing, but just to eat a balanced diet. I’ve lost weight in the last year by eating tons of fiber (oatmeal, whole wheat bread), a fair amount of protein (cheese made with part-skim milk, beef, chicken, turkey), drinking only water and tea (to which I don’t add sugar), having a salad every day (no dressing), and allowing myself to eat at least one pretty unhealthy thing (ie, a 500 cal cupcake, a piece of cake, etc.) on most days that I go to the gym. I’m not saying do this, but I am saying that simple awareness of what one is eating can make a big difference.

      I’m not saying there aren’t some valid things in this argument; I do think that the original poster’s dismissal of the rebuttal as unconvincing is really missing how flawed Lustig’s argument is. Just look at his “solution” to this problem:
      “If you want to stay healthy, get rid of all sugared liquids. Drink only water and milk. Eat carbohydrates with fiber, and wait 20 minutes before you eat a second portion, to get the satiety signal. “Buy” your screen time with an equal amount of physical activity. If you go out and play for 30 minutes you can watch TV for 30 minutes. In his clinic, these measures work – BMI z-scores steadily decrease from baseline over 30 months. Multivariate linear regression analysis shows that the one thing that prevents this from working is sugared beverage consumption. The more sugared beverages his patients drink, the less well the lifestyle interventions work.”

      He throws out some math that most readers won’t understand to try to demonstrate that his connection is there; multivariate linear regression analysis can show correlations of many sizes, he doesn’t even say that this is the greatest correlation, he just says that it’s one of an unknown number. Meanwhile, the advice he gives is exactly what any good diet would tell you to do. Everyone should eat more fiber. Everyone should try to get at least 20 minutes of exercise each day. Of course it works. This is the textbook recommendation for being healthier. It in no way draws a connection that the cause of all of this is fructose.

      I don’t know. This just bugs me because it all sounds so much like something that could be used an excuse: “it’s not my fault, exercise won’t fix this, the corporations are putting hfcs in everything, that’s why I’m fat.” And…there’s just so much of it that is wrong, but by cloaking it in all that biochemistry, he makes it sound like we’re all too stupid to understand how correct he is.

      Anyway. This rambling rant took the time I had planned to use for responding to the WoT post more. Next time… πŸ™‚

      • unforth

        A couple related things that might help:
        What is Metabolism – the intro to the wiki article sums it up.
        What a calorie is – “calorie” is simply a unit for measuring energy.

      • unforth

        I just realized a better way to express my problem with this: it’s reductionist. Any attempt to look at the obesity problem in this country and point at one thing and say “this is the problem” is guaranteed to be wrong. There isn’t only one cause. But human brains really don’t like multivariate problems, they like dichotomies, and this is a prime example of (in my opinion) pretty bad reductionism.

      • Marie Brennan

        Meanwhile, the advice he gives is exactly what any good diet would tell you to do. Everyone should eat more fiber. Everyone should try to get at least 20 minutes of exercise each day. Of course it works. This is the textbook recommendation for being healthier.

        It’s the first one I’ve seen, though, that says fruit juice may not be as good of an idea as I assumed it was. That’s what caught my eye. And it’s the first one that convincingly outlines a metabolic difference between different types of sugars, and what happens when they’re consumed in conjunction with other things. I don’t think it comes across like the Atkins diet, though, because it doesn’t claim “you can eat anything you want so long as you avoid fructose!” It says, “here’s what I think is one of the underlying rationales for the textbook recommendation.” Everything I’ve seen up until now has made that recommendation on the basis of generalized common sense; but there must be some kind of biological basis for it, some reason why our bodies react differently to Diet X than Diet Y. (Using “diet” in the scientific sense of “what you regularly consume,” not “weight-loss diet.”)

        This just bugs me because it all sounds so much like something that could be used an excuse: “it’s not my fault, exercise won’t fix this, the corporations are putting hfcs in everything, that’s why I’m fat.”

        This is quite possibly true. Anything touching on nutrition and weight wanders between two swamps, one consisting of “it’s all corporations/genetics/something else I can’t control,” and the other consisting of “fat is a moral failing I could overcome if I were just a better person.” Neither of which is good for anybody. But there has to be some constellation of answers that explains why things have changed over the last three decades or so; neither the seemingly “simple” equations of calories and exercise appear to cover it completely on their own, and you won’t convince me that either our genetics or our morality have radically changed since I was born. So I look for other factors, and I think it’s possible that this is at least one of them, if not the demon at the heart of it all.

        • unforth

          I unfortunately haven’t researched the benefits or harm of fruit juices at all, for the simple reason that for the past 10 years I haven’t been able to drink fruit juice without getting a massive stomach ache (gas and worse…). I love juice, but I can’t drink it for reasons completely unrelated to health and fitness. What says about drink cals is what I’ve read too, though, and is why I only drink water. If I drink a cup of milk, my body will act as if it’s had nothing at all; if I eat a slice of cheese (same number of cal) my body acts like I’ve had something to eat.

          I’d say if you’re attracted to juices, you can make it work, but avoid ones that have sugar added. (like, squeeze your own OJ kinda thing. πŸ™‚ )

          • Marie Brennan

            Lately I’ve been on a kick of buying a half-gallon of unpasteurized apple cider from the farmer’s market every week. As fruit drinks go, I could probably choose far worse.

      • Marie Brennan

        This rambling rant took the time I had planned to use for responding to the WoT post more.

        Dammit! I’m looking forward to that. πŸ™‚

        • unforth

          I’ll try. πŸ™‚ I’m just not very focused today, and I’ve been really struggling to get through things I have to do, and I still have a couple important ones left. πŸ™‚

    • Marie Brennan

      Hmmm. Your counter-arguments don’t read as much of a disagreement, to me at least; it sounds to me like your points are not far off what I took away from the post.

      Exercise does burn calories.

      He didn’t say that it didn’t — just that looking to the calorie-burning end of things as the sole (or even major) explanation of why exercise works doesn’t cut it.

      Beyond that, though, the paragraph is just confusing and inaccurate. Exercise makes the TCP cycle go faster because you need the ENERGY thus produced in order to make your body do things, and calories are one way of expressing that energy.

      What you say in the rest of that graf doesn’t come across to me as a contradiction of his point — more an expansion of it. “I ran twenty minutes and burned eighty calories” (or whatever) would not, on its own, explain weight loss. But the rest of it, the part where a fit body burns more calories just by existing than a non-fit one does, explains a lot more.

      Lustig tries to say that Fructose metabolizes into fat, so it’s bad – but according to wiki (and I see no reason to doubt it on this point) that same substance builds our muscles. That means we need it.

      Yes, we do — and like I said, I think he goes overboard in calling it a poison. Obviously we shouldn’t cut it entirely from our diets. But his points about the difference between consuming fructose in conjunction with fiber, and consuming it without, seemed sensible to me, as do the points about how our consumption (whether via sucrose or HFCS) has risen over the years.

      Also, as far as I can tell, he pretty much completely ignores the exercise question. He talks about people eating more, and what they are eating, but doesn’t at all discuss evidence that suggests that people are much less active than they used to be.

      I haven’t watched the video, but the summary touches briefly on that in the “What to do about it” section; it claims there was a distinct difference between people who pursued a less sedentary lifestyle while cutting sugared drinks, and those who did the former but not the latter.

      Regulation: no argument here. Like I said, I think his end-point attitude is overblown.

      • unforth

        I can live with that. πŸ™‚

        Just to make one point, though, the summary in the link says that “exercise does not work by burning calories” – but our bodies wouldn’t do the things we were exercising to do if it wasn’t burning calories. πŸ™‚

        I guess what I’m trying to say (as we are in agreement) is that the parts of what Lustig says that aren’t blown out of proportion aren’t new ideas. πŸ™‚

        • Marie Brennan

          Okay, I see the unclarity there. I read it in the sense I think he meant it — “exercise doesn’t make you lose weight just by the calories you burn while doing it” — but the phrasing could have been better.

          Lustig’s points may not be new ideas at all, no. But they’re actually new to me, or at least the explanations behind them are; everything else I’ve seen on this specific topic has been hand-wavy in the extreme.

          • unforth

            I hear ya. I do think a lot of the problems with this account may actually lie with the person who wrote all that down, maybe not with the original video (which I didn’t watch) – this is not a very well written account, and I can’t escape the impression from reading it that the person who put it together doesn’t have a clue what a calorie IS – it reads like they think a calorie is an actual “thing.”

          • Marie Brennan

            Quite possibly. The video was just too long for me to devote that time to it, though.

          • unforth

            Also: I guess I’m surprised that it’s new to you. I think of you as one of my health-conscious, knowledgeable friends on this sort of thing, so I didn’t expect that. πŸ™‚

          • Marie Brennan

            Nope. I’m flattered you think that, but when it comes to nutrition, I’m quite ignorant. What I know about health applies much more to the exercise end of things.

          • unforth

            If you thought it’d be helpful, I could write up a quick and dirty run down of my understanding of how things work. I’m sure I’d get some details wrong, but I’ve got a decent understanding of the outline of how nutrition works. I had to learn – before I started dieting, I didn’t understand at all, not even the slightest clue (beyond “fat is bad” and “sweets are bad”), so I studied up. πŸ™‚

          • Marie Brennan

            I might take you up on that — but I’d rather have the TDR commentary. πŸ™‚ (Shows where my priorities are . . .)

          • unforth

            lol. Okay, I take the nudge. I’ll have a bunch of time tomorrow. I will do my best to get to it then, promise. πŸ™‚

  3. tiamat360

    Hrm. I didn’t watch the video, but I skimmed the LJ post, and now I’m wondering if I ought to take the time to watch the video. Many of the points announced in the LJ post made me raise an eyebrow. For example, exercise speeds up the TCA cycle so you precipitate fewer lipids? Um. Disregarding some language confusion (precipitate?), the idea behind this just doesn’t make sense to me. Acetyl-CoA, the basic building block of fatty acids, does get consumed in the TCA cycle – but it also gets regenerated. There is no net gain or loss of acetyl-CoA, so changing the rate of the cycle shouldn’t change how much sticks around. What altering the rate of the TCA cycle does do is increase the use of pyruvate, and therefore glucose, and therefore your body thinks it’s starving and drops the rate at which fatty acids are made.

    Another thing that’s bothering me is how they get from phosphorylation of fructose –> uric acid. The post seems to say that fructose phosphorylation consumes ATP (true, I believe), ultimately leading to the breakdown of the nucleotide to uric acid. However, the liver uses ATP for all kinds of reactions (not least of which is gluconeogenesis); does starvation lead to excess uric acid production? Furthermore, ADP doesn’t automatically enter the purine degredation pathway (in fact, ADP is rarely involved – usually it’s adenosine (no P’s), being made into AMP then getting degraded). Your body would be much happier regenerating the ATP from ADP (say, using electron transport chain??) than throwing it out.

    Anyway. Some problems with juice, unrelated to fructose specifically:
    1) We add extra sugar to juice in the US. So it’s usually just as caloric as pop, even though it really doesn’t have to be. Um, oops?
    2) Juice (and pop, and any other sugared beverage) doesn’t alter how much food you consume. So, if you drink a cup of juice with 150 calories, you’re still going to eat the same amount of food that you would if you hadn’t drunk that juice, plus you got 150 calories out of it.

    In short, I don’t think fructose is a horrible evil villain. Sure, too much is bad for you, but that’s not much of a surprise. Overconsumption and lack of exercise are far, far worse.

    • Marie Brennan

      So you don’t buy into the leptin end of the argument, where fructose (from whatever source) alters the sense of satiety? I’d heard a non-technical version of that argument before, but solely in the context of HFCS, not fruit juice — and, because biochemistry is not a strong point of mine, I never realized that sucrose actually consists of fructose and glucose. I thought it was an entirely different sugar, and somehow “better” than HFCS. (See above comments about previous things I’ve read on this topic being hand-wavy in the extreme. At least this guy shows his math, so to speak.)

      • tiamat360

        Never heard of the idea before now. Wikipedia cites some legit scientific articles about it; not having read them, I don’t know how much I agree with their data/conclusions. I do know, however, that the person whose LJ you’ve linked to has some very wishy-washy science: he says that insulin stimulates leptin production, and since insulin is stimulated by glucose and not fructose, you get less leptin if you eat fructose…which is simply not true – the amount of circulating leptin is proportional to the amount of adipose tissue you have, and to the best of my knowledge, has nothing to do with insulin. The articles cited on Wikipedia discuss fructose and leptin resistance, which has to do with how the body/brain responds to leptin, not whether it’s being produced or not (think type II diabetes).

        Maybe there is something inherently worse about fructose ::shrug::. Chances are it’s not as bad as this person is making them out to be, and that if you consume fructose in moderation you’ll be fine. Also wishy-washy science makes me sad :P.

        In a counter-argument of sorts, it’s interesting to point out that fructose, or fructose containing foods, have a low glycemic index. They are therefore considered more “healthy” precisely because they don’t cause insulin synthesis and release. (The idea being that rapidly increased insulin leads to plummeting blood sugar leads to hunger leads to eating more.)

  4. diatryma

    I have not read the articles, but it turns out a friend of mine is… fructose intolerant? Something like that. I’m getting the news secondhand.

  5. Anonymous

    Well, my biochemistry degree is a bit stale…

    * The key problem is not “fructose” or “sucrose” or “glucose,” but purity, refining, and concentration. And the problem arises as much from the imbalances that causes in the GI tract as in cell and liver metabolism.

    * Exercise works not just by raising metabolic rates, but by marginal changes in the type and ease of energy storage. The balance between direct storage of sugars (either in the bloodstream and in cells or as glycogen in the liver) and longterm storage by building lipids (fats) changes. This can be a bit hard on the kidneys… which is one of the reasons that one must drink more fluids on a heavy exercise regimen, to help flush stuff through the kidneys without causing crystalization.

    * And, as a bonus, that hydroxyl group hanging off simple and complex sugars looks an awful lot like the hydroxyl group hanging off of ethanol to a lot of enzymes… which is one reason that sugar and alcohol metabolism are both centered on the liver. In turn, this has huge effects on a wide variety metabolic balances.

    Ultimately, the key point is this: Primate biochemistry and metabolism is best managed through a varied diet. ANY extreme is bad for the primate GI tract and liver; Atkins is just one example.

  6. pentane

    I found the most telling fact in the stats posted in the counter point. On average, we have 600 more calories a day in our diet.

    That’s an extra pound to burn off every 6 days.

    I’m a pretty fanatical calorie counter myself. If you figure out how many calories you can take in a day and try and balance a diet while hitting that number, you will lose weight.

    It’s even self correcting… sure I can eat 3000 calories of chocolate chip cookies, but I will not feel good when I do, and once I get done eating the stuff I “need” to eat, there’s not a lot of calories left in the day for other stuff.

    Of course, I got sick of feeling hungry all the time, so I’ve said that I can live with those 15 extra pounds if it means I won’t think about eating all the time.

    I have a generic problem with any arguement about specific foods being good or bad. Anything is bad in large enough quantities, and our individual metabolisms are different enough (skimming through comments I see people that are fructose intolerant, go crazy from artifical sweeteners, etc) that you need to figure out what works for you and listen to your body.

    Just for the record, apple and orange juice are 7-8 quarts for a pound of calories. A case of coke (and a case of beer) are also a pound of calories.

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