Monday, 12 November 2012

What is wrong with sugar? "Sugar: The Bitter Truth"

In 2009 Robert H. Lustig, MD, UCSF Professor of Pediatrics in the Division of Endocrinology, presented a seminar for the UCSF Mini Medical School for the Public called Sugar: The Bitter Truth.
Below is my summary of what he presented. The seminar is one and a half hours long and you can watch it here Sugar: The Bitter Truth. In my opinion this is critical viewing, and I strongly urge you to take the time.
If you have concerns about the following information, do discuss them here, but remember this is Robert Lustig's research that I am summarising.

Since the 1970s, as fat has been reduced in our diet, sugar and carbohydrate consumption has increased. Fat used to provide the flavour, and sugar has taken its place.

We have reduced our fat intake, but rates of obesity metabolic syndrome (obesity, type II diabetes, lipid problems, hypertension, cardiovascular disease) have all gone up. Why?...

"It ain't the fat people, it ain't the fat." It's the carbohydrates. Sugar.

In the 1970s we learnt that dietary fat increased LDLs ("bad cholesterol"). An increase in LDLs led to Cardiovascular Disease. And so we were told to decrease our fat intake. HOWEVER:
We now know that there are actually 2 kinds of LDLs, the neutral ones, that have no effect on our arteries, and the "bad guys." Dietary fat increases the number of neutral LDLs. And guess what increases the bad guys? Carbohydrates. But, we decreased fat in our diets, and replaced it with carbohydrates, specifically - sugar. And that was the worst thing we could do.
Read that again and again until you get it - it's crucial!

So what is wrong with sugar?

Sugar is 50% glucose and 50% fructose. Glucose is good. Fructose is bad.

When you eat glucose, 80% of the calories are taken up and used by all the organs in the body. Every cell in the body uses glucose. It is the energy of life, and it is what we were supposed to eat.
20% goes to the liver. And the liver can handle any amount of glucose that is thrown at it. Maybe about half a calorie ultimately gets stored as fat.

When you eat fructose, 100% of the calories have to be metabolized by the liver. The rest of the body can't deal with it. When an entire compound has to go to the liver because only the liver can metabolize it, and in the process it creates a variety of problems, we have a name for this... we call it a poison.

30% of fructose calories end up as fat.

Chronic fructose consumption leads to:

type II diabetes
lipid problems
increase in uric acid causing gout
increase in blood pressure and therefore hypertension
cardiovascular disease
myocardial infarction
hepatic dysfunction
fetal insulin resistance
habituation, if not addiction

The way fructose is metabolized and the problems it leads to are extremely similar to those of chronic ethanol exposure (heavy drinking).

Fructose does not suppress the hunger hormone. Your insulin doesn't go up, your leptin doesn't go up, and so the brain does not know that you have eaten and therefore you eat more. We are eating more and more and we don't know when to stop. Thanks to sugar.

As fat has been reduced in our diet and sugar increased, fibre has also been decreased. It's too slow to cook, too slow to eat, and decreases a product's shelf life. But fibre reduces the negative effects of fructose. We should be eating our carbohydrates with fibre. So don't worry, fruit is OK: "when God made the poison, he packaged it with the antidote" - fruit contains both fructose and fibre.

Fruit juice is stripped of fibre. So you can pour fructose down your throat, or down the sink. Dr Lustig's first recommendation for reducing and removing fructose from your diet is to pour your juice down the sink.

Fructose is a carbohydrate, but it is metabolized like a fat.

"A high sugar diet is a high fat diet"

A few further points:

You can't exercise enough to burn the calories you are eating. This is pretty much impossible. ("C'mon, 20 minutes of jogging for one chocolate chip cookie. You can't do it. Are you joking me?") Exercise is important because it reduces obesity for more complicated reasons (see video at 1hr 11 mins). But it doesn't burn calories.

If you are living and eating in the USA you have one massive High Fructose Corn Syrup problem. You should watch this whole video (specific details are at 17 mins and at 1hr 11 mins).

If you are interested in the LDL/cholesterol discussion:
for the reasons explained above regarding the 2 types of LDLs, Lustig suggests tryglicerides are a better measure of cholesterol than LDLs (low TGS and high HDLs are good, high TGS and low HDLs are bad). You may have picked up that this LDL discussion has massive consequences for our diet, regarding more than just sugar. That's a topic for another day.

And finally. In the North and South Magazine article "What's Making us Fat. Surprising new discoveries on why we gain weight" by Donna Chisolm (November 2012, great timing huh?!) we are told this:
The American Heart Association recommends a daily intake of 9 teaspoons of sugar a day for men, 6 for women, and 3 for children. We have a median intake of 30 for men, 24 for women, and 26 for children. 

We should probably do something about that.


  1. Eek! Thanks for the research Angela.

  2. Really Interesting stuff. I have been hearing stories of transformation from some friends who have gone sugar free over the last few years, and have felt inspired to try on various occasions, but still find it all a bit overwhelming. Seems such a challenge to go completely sugar free. So we are making changes where we can and I'm trying to find some good sugar free recipes. Keen to hear your take on Stevia, and lower GI options like molasses. So enjoying this (and trying not to let it get overwhelming!) Angela. Thanks! xx

  3. Thank you for sharing your findings Angela, I look forward to your sugar-free recipes! I feel uncomfortable about that last statistic - that women are consuming 4 times more sugar a day than we should...oh dear

  4. Yes, thanks for all your research Angela. I watched the whole seminar/lecture this evening. Very interesting indeed. And I too was very disturbed by that last statistic. The question I am now pondering is how much frustose am I consuming? Can this be decreased by eating less processed food?

  5. I think what I find most shocking about those final statistics is that children are consuming more sugar than women, when they should be having only half the amount. I'm sure (though I've not been able to find them easily) that the UK figures will be just as shocking as those from NZ. I am going to have to seriously consider the amount of fruit juice our two drink - and there was I thinking I'd done a good thing switching them from squash to juice...
    Thanks for all the work you're putting into this, Angela.

  6. That's very interesting and definitely food for thought. There was a similar message in recent BBC programme here in the UK - "The Men Who Made Us Fat" -

    I'm very glad I don't live in the US and have to avoid so much of the HFCS.

    Alex - I'm not sure I'd worry so much about the fruit juice (in reasonable moderation of course). The figures for the amount of sugar eaten by children will presumably include children up to the age of 12 at least and a lot of these, at least in the UK, will be regularly eating high sugar cereals, sweets & chocolate snacks and probably quite a lot of fizzy drinks. At least fruit juice has a nutritional benefit. Also, while large quantities of sugar are obviously not good, I'm still not convinced that we should be eating large quantities of the replacement sweetners - Aspartame has been the subject of much speculation as to its safety.

    We should probably eat both sugar and replacements like aspartame in moderation, but eat less of all types of sweet food - unfortunately, that's easier said than done!

    Really interesting stuff though Angela - and I look forward to trying out some of your sugar-free recipes.

    1. Hi Caroline, yes I wouldn't go near Aspartame and artificial sweeteners, but I am pleased to report that there are other options, and so far they look to be pretty good. You can have a read of my sugar alternatives page here:
      My current favourites are xylitol and Sweet Freedom, and I am also working with glucose/dextrose at the moment, which I haven't written about it yet but it's looking good.
      The question of fruit juice is an interesting one that we might discuss in a new post soon. I would question the nutritional value of many fruit juices other than freshly squeezed 100% juice, but perhaps this is something we could look in to.
      It horrifies me to think that those children who are eating all the stuff you mention above will be eating well above the median of 26 teaspoons a day! But like you say, for the moment at least, we just need to worry about our own intake (before we change the world).

  7. You have definitely succeeded in making me think about how much sugar my family and I intake. I too am looking forward to some sugar free recipes, or ones made with natural alternatives :) I dont think I will ever completely cut sugar out of my diet, for us it just doesnt seem realistic and I do believe in all things in moderation - I guess now it is just about learning to moderate.

  8. Hi Angela. Rachel sent this on to me.

    A query. Your summary is interesting and appears to make sense, but as I don't know really know anything of the chemistry and biological functions involved, I'd like to hear/observe a discussion between him and any critics. Has anyone critiqued this guy, and if so, has he responded?

    1. Hi Renton, yes this is something I have been looking at over the last day or so and am working on how to discuss it on The Cook's Sponge. The main objections appear to be lack of definitive studies that really demonstrate the negative effects of fructose. Lustig certainly refers to quite a number of studies, but the argument is that they do not have enough numbers to come to definite conclusions. I must say it was the chemistry and biology that I found the most compelling; studies looking at the effects of soda on a group of teenagers seemed less relevant to me, but perhaps that is where I show my ignorance.

      The other question is around how much fructose is needed to create these effects. I'll paste in a whole lot of links that I am looking at, you may like to have a read. Some of the arguments don't hold enough weight for me. David Katz's argument that we are are born with a natural instinct for sweetness strikes me as completely irrelevant to the discussion, and his comments regarding fruit make me wonder if he even heard what Lustig had to say on the topic.

      I presume you have watched the seminar, and not just read my summary? To be able to engage in the criticisms at any useful level I think it would be necessary to hear all of what Lustig has to say first.

    2. Here is something else that I've come across but haven't looked at yet.

    3. Renton and Angela, have you read this critique of sweet poison?

      This is the bit I found most interesting:
      (v) On page 78 the claim is made that 'every gram of fructose we eat is directly converted to fat'. This is not correct—fructose may go down the gluconeogenic pathway (leading to its conversion to glucose and subsequent storage in the liver as glycogen) or the fructolytic pathway (resulting in the production of fat). The available evidence suggests that fructose may be preferentially converted to glycogen until liver glycogen is replenished. It appears that only then will the fructolytic pathway predominate [Biochem. J. (1988) 251 (3): 795–802].


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