"Wait, wait, wait, wait a second. You're tellin' me that I came all the way to Kentucky to get some of your fried chicken, and the Colonel isn't even workin' today?!?"
-- Peter Griffin

Wouldn’t it be sweet

Limbo & I were discussing something I had heard about artificial sweeteners and how they are linked with weight gain while I was visiting her last weekend. I wasn’t sure of the mechanism, but the following Globe & Mail article does a pretty decent job of explaining the connection. Turns out the digestive tract has taste buds too, and when they detect sweetness, the body responds by releasing hormones to increase the body’s absorption of glucose. “That means that even though a diet soft drink is sugar-free, the artificial sweetener leads to a greater uptake of sugars from other foods that might be in your belly at the same time”. Now if I recall my biochemistry correctly, all foods when digested break down into some proportion of glucose, even meat. Am I remembering correctly?

4 Responses to “Wouldn’t it be sweet”

  1. Nope, that’s not quite right. All carbohydrates will break down into sugar, but fats and proteins are broken down into glycerin and amino acids, which might then be broken down further into ketones rather than glucose. Ketones (unlike glucose) aren’t converted into fat when left unused. This is the essential basis of the Atkins system (and what the fad Atkins pretenders claim to support).

    Have a look at this page for a good description: http://wilstar.com/lowcarb/chem.htm

    (BTW, for the Atkins-naysayers, the real trick of course is forcing your body into breaking the fat and protein all the way into ketones rather than just storing the fat. If your body doesn’t consistently stay in ketosis, the Atkins diet is actually less healthy than a standard low-fat, low-calorie diet.)

    Looking at the Globe article, it’s hard to tell how valid their conclusions are. Everything I’ve read has said that unused glucose in your body will always be absorbed into the bloodstream (i.e. it will not be excreted), and this study only seems to imply that the absorption rate may be quicker if you’ve ingested artificial sweeteners, i.e. you have less time before your body considers the glucose to be “unused”. So for the majority of people who don’t run a marathon after that plate of pasta washed down with a diet pop, I can’t see this discovery making a huge difference. :-)

    Note that they’re still saying that drinking an artificially-sweetened drink is still probably better than a drink full of sugar. And the related point that “people who down diet beverages are just as likely to develop heart disease and diabetes as those who consume sugary drinks” ignores a basic premise of science: correlation does not imply causation. The reality is that most of the idiots in the world who drink diet beverages do so in the complete absence of any other kind of diet changes (think of the people who order a diet Coke with their Big Mac and fries).

  2. Actually, Kaveman, check your reference more carefully… in the section of your wilstar.com website entitled “Relevance to dieting”, it says the following:

    “If you eat a hypothetical diet consisting of 70% carbohydrates and 30% protein with no fat, some of the protein will be used for body building and repair, and some will be converted into glucose.”

    Later in the text it indicates that as much as 58% of the protein can be converted into glucose. (admittedly, not sufficient for the body’s uses, hence the basis for low-carb diets, but glucose is still produced).

    That being said, that doesn’t explain everything to my satisfaction. e.g. Does the study referenced in the G&M refer to the hormone insulin, or other hormones? (I think they are vague on this point.) Where does protein conversion to glucose take place, in the gut or eslewhere? Under normal cicumstances, does all the glucose resulting from food being broken down in the digestive tract get absorbed, or is some excreted? Time to break out those biochem notes, I guess…

  3. Now for some flexing of medical biochemistry muscle:
    1) Yes, Binz, that is true: unused protein can be converted into glucose. This happens in the liver. Given that most of the average North American diet is protein rich, that’s a fair glucose load right there. This is a protective mechanism for the body: the ONLY fuel that brain cells can use is glucose (though ketones can be used in a pinch, glucose is the preferred fuel), hence the “back-up” ways of getting more glucose in times of starvation (i.e. use from either protein sources, or production of ketones);
    2) The hormone they indeed refer to would be insulin: it’s the body’s main anabolic (building up) hormone, and causes us to pack on the pounds. In patients with very little insulin production (type 1 diabetes, the type usually seen in children), they eat enormous amounts of food but actually LOSE weight. In fact, our teenage diabetics often “forget” their insulin in order to drop a few pounds before prom…
    3) We do not absorb all glucose: some is excreted in our feces, along with unused fats and carbohydrates. Interestingly enough, a recent study found how much food we actually absorb is likely based on what kind/proportions of gut bacteria we have: hence, perhaps an explanation why some people can eat like a horse and stay skinny, while others diet continuously and still are fat.

    Hope that helps! :D

  4. Grabber, can you add a #4 to your analysis and describe ketosis? I’ve obviously misunderstood something here, but I’m not quite able to put my finger on what, exactly… :-)

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