August 28, 2002
From the desk of Jane Galt:"So if you don't think
"So if you don't think that fat calories are better for you than sugar calories," ask several emails, "what do you think makes Atkins work, Miss Smartypants?"
Well, first of all, thank you to the eight hundred people who wrote to tell me that the important thing isn't metabolism; it's the effects on appetite due to the slower digestion of fat, and the steadier blood sugar levels. I agree with that, and indeed, I wrote about it in my first post on the subject.
I also think that most people on Atkins probably aren't eating that much more fat than they used to. Aside from meat, what does fat taste good with? Carbs! Bread and butter, french fries (McDonalds french fries have more calories than the burgers, and something like 75% of those calories come from fat), cheese on pasta, luscious, fatty desserts laden with sugar and butter. After you cut all of that stuff out, the fat you're getting from salad dressing and meat probably isn't much higher (for most people) than what they were eating before.
Which brings me to the second point -- fewer calories. First of all, on Atkins there's a ton of stuff you can't eat. I've sat with friends at restaurants, watching them pore over their choices, and like as not they end up with the low-calorie fish dish because it comes with the veggie sides, instead of the potatoe or rice. Second of all, the stuff you can eat is harder to overeat. Most of us can chow down on a loaf of bread or a huge dish of pasta, but it's hard to eat twice as much steak as you meant to, at least for most of us. Third of all, I believe that there are suppressant effects on appetite, due to the aforementioned gastric emptying rate. And fourth of all, fatty substances by themselves aren't snack food. How often have you watched a co-worker stand by someone's candy dish, absent-mindedly popping candy or chips into their mouth as they tlaked? Now how often have you seen someone do that with, say, a hunk of cheese? Even if it didn't have to be refrigerated. So you get fewer "uncounted" calories -- the kind no one bothers to factor into their running total of what they've eaten because it was just a little penny candy, but which could easily be 200-300 calories a day.
I believe Atkins works. I've seen it do so. My contention was only that Atkins was not working because fat calories aren't real calories, which is an argument I've seen over and over. It works because you're eating less than you're expending, which is how all diets that work, work.
To my mind, Atkins is a heuristic. By putting entire large categories of food off limits, it causes you to cut your calories with minimal mental effort. As long as the heuristic isn’t too restrictive, I think such diets can work over the long term. I knew a model who had a different color on each day of the week: blue for Monday, red for Tuesday, etc. On that day of the week, she only ate food of that color. It made her skinny; she was the girl they got to model the “support garments”, because there wasn’t an ounce of fat on her to bubble over the elastic waistband. But it didn’t work because there’s some magic in food colors, though as I recall, she believed there was; it worked because on “purple” day, all she was eating was blackberries and eggplant. Vegetarian diets work the same way, when they’re done right; to be a healthy vegetarian, you have to eat a lot of complex carbohydrates, which take the place of the empty you’d otherwise consume. It’s tough to get enthusiastic about a baked potato with sour cream when you’ve just eaten a half a pound of rice and beans.
I actually think the low fat diets used to work the same way. When they came out, they got just as much buzz as Atkins gets now. But think of everything you’d be cutting out, in 1980, if you cut out the fat. Who wants bread or a baked potato without butter? Jello without whipped cream? No ice cream, cookies, candy bars, cream sauces, not even that many simple starches; none of the low-fat, high sugar substitutes we take for granted, like frozen yogurt and reduced-fat cookies, had been invented. The diets claimed if you counted the fat grams, you wouldn’t have to count calories. Which was true, because given the foods available at the time, anyone serious about cutting fat would also be cutting their calorie intake.
The problem is, as marketers worked to capitalize on it, they found ways to make empty calories – simple starches and sugars – low fat. People who had been holding off on low fat diets now found that they were quite palatable. Which was because they now had more calories.
So I think Atkins works on much the same principle. And I think that if we saw widespread adoption, we’d see more and more high-fat products come out that would do to Atkins followers what Snackwells did to the low-fat disciples – up their calories intake without their realizing it until they started to gain weight. But that’s just my opinion. I could be wrong.
Anyway, my beliefs about dieting were summed up by my coworker when she saw this week’s Time Magazine headline: “What Makes You Fat?”
“I don’t even need to read the article,” said Ewa. “The answer is ‘sitting on your ass and eating all the time.’ ”
Posted by Jane Galt at August 28, 2002 01:45 PM | TrackBack | Technorati inbound linksAbout a decade ago, I was taking a course in undergrad biochemistry. The topic of one day's lecture was glucose (blood sugar) metabolism, and it reminded my professor of "this crazy fad diet back in the 1970s."
She went on to describe how "some quack doctor" came up with the idea of eating only fat and protein to lose weight, and evoked the "ridiculous" image of people going into fast food restaurants and ordering a hamburger, and then throwing away the bun. I looked around the class and saw my fellow students were similarly appalled; it seemed far too absurd to believe.
When she said that the kicker to this story was that the diet actually worked, we were incredulous. She went on to explain the basis for why it worked, though, and it made a terrible kind of sense.
The blood-brain barrier, you see, is extremely selective. As a result, the cells in the brain depend almost exclusively a single source of energy - glucose. In a normal diet, this is provided by the sugars and the breakdown of starches. But in this diet, you get few to none.
When the brain recognizes that it's not getting enough glucose, it first starts freeing up stored glucose. These reserves don't last any appreciable length of time, though - and the brain HAS to get glucose, since it can't stop functioning. Plants have little trouble making sugars and starches through photosynthesis, but we're not similarly equipped.
What the human body has to do is 1) break down fat and protein molecules from your diet and your body, then 2) use an incredibly energy-wasting process to build glucose molecules up bit-by-bit from units of two of the many fragments, pyruvate and lactate.
On its face, it sounded almost positive, although strange. This diet would reduce the amount of energy your body receives from food to a fraction, by taking advantage of the body's emergency mechanism for starvation. In fact, one of the students asked Dr. Katz, "Then why aren't people using this diet now?" with a hopeful look.
"Because," Dr. Katz told us, "it got quite a bad name from some of the inconvenient side effects. All of that energy is being wasted, but it has to go somewhere. Any ideas?"
I ventured, "Heat?"
Dr. Katz nodded, and went on to explain that people who were on the diet would typically run very high body temperatures. One effect would be that the typical dieter would be miserably hot, in addition to ill mood from low blood sugar. A second, more pernicious effect was that the cells of the retina are extremely sensitive to heat - and in some cases, people who overdid it went blind.
The same student who'd asked why this diet had fallen out of favor now asked, "But what if you just didn't exercise and turned up the air conditioner?"
Dr. Katz went into a laundry list of reasons, most of which I've forgotten. But chief among them was that buildup of pyruvate and lactate to the concentrations needed for gluconeogenesis results in elevated "ketone bodies" as side-reaction byproducts, acidifying the blood by degrees. The extreme of this condition is ketosis - diabetic shock.
Another that I'd add on in retrospect from later classes in grad school would be this: Your liver is the primary organ for constantly detoxifying your blood. One of the major mechanisms it uses for this is to attach a glucose molecule to a molecule it "thinks" might be toxic, so that it washes out of the body on its next pass through the kidneys. When glucose is scarce, though, the brain takes precedence - and this mechanism is rendered mostly ineffective.
We were pretty-well convinced by the time Dr. Katz returned to describing normal function of the body, which is breakdown of glucose. Even the hopeful student compared it to running a car without oil - necessary in an emergency, but a really bad idea for general use.
Skip forward seven or eight years, and I'm reading about some "new" diet that's becoming popular. "Hmmmm, strange. Wait a minute, no carbohydrates... Is this.... Oh my God, that must have been the name of the quack who Dr. Katz couldn't remember! Atkins!"
And so it goes. :-)
Posted by: David Reynolds on February 13, 2004 07:03 AMAbout a decade ago, I was taking a course in undergrad biochemistry. The topic of one day's lecture was glucose (blood sugar) metabolism, and it reminded my professor of "this crazy fad diet back in the 1970s."
She went on to describe how "some quack doctor" came up with the idea of eating only fat and protein to lose weight, and evoked the "ridiculous" image of people going into fast food restaurants and ordering a hamburger, and then throwing away the bun. I looked around the class and saw my fellow students were similarly appalled; it seemed far too absurd to believe.
When she said that the kicker to this story was that the diet actually worked, we were incredulous. She went on to explain the basis for why it worked, though, and it made a terrible kind of sense.
The blood-brain barrier, you see, is extremely selective. As a result, the cells in the brain depend almost exclusively a single source of energy - glucose. In a normal diet, this is provided by the sugars and the breakdown of starches. But in this diet, you get few to none.
When the brain recognizes that it's not getting enough glucose, it first starts freeing up stored glucose. These reserves don't last any appreciable length of time, though - and the brain HAS to get glucose, since it can't stop functioning. Plants have little trouble making sugars and starches through photosynthesis, but we're not similarly equipped.
What the human body has to do is 1) break down fat and protein molecules from your diet and your body, then 2) use an incredibly energy-wasting process to build glucose molecules up bit-by-bit from units of two of the many fragments, pyruvate and lactate.
On its face, it sounded almost positive, although strange. This diet would reduce the amount of energy your body receives from food to a fraction, by taking advantage of the body's emergency mechanism for starvation. In fact, one of the students asked Dr. Katz, "Then why aren't people using this diet now?" with a hopeful look.
"Because," Dr. Katz told us, "it got quite a bad name from some of the inconvenient side effects. All of that energy is being wasted, but it has to go somewhere. Any ideas?"
I ventured, "Heat?"
Dr. Katz nodded, and went on to explain that people who were on the diet would typically run very high body temperatures. One effect would be that the typical dieter would be miserably hot, in addition to ill mood from low blood sugar. A second, more pernicious effect was that the cells of the retina are extremely sensitive to heat - and in some cases, people who overdid it went blind.
The same student who'd asked why this diet had fallen out of favor now asked, "But what if you just didn't exercise and turned up the air conditioner?"
Dr. Katz went into a laundry list of reasons, most of which I've forgotten. But chief among them was that buildup of pyruvate and lactate to the concentrations needed for gluconeogenesis results in elevated "ketone bodies" as side-reaction byproducts, acidifying the blood by degrees. The extreme of this condition is ketosis - diabetic shock.
Another that I'd add on in retrospect from later classes in grad school would be this: Your liver is the primary organ for constantly detoxifying your blood. One of the major mechanisms it uses for this is to attach a glucose molecule to a molecule it "thinks" might be toxic, so that it washes out of the body on its next pass through the kidneys. When glucose is scarce, though, the brain takes precedence - and this mechanism is rendered mostly ineffective.
We were pretty-well convinced by the time Dr. Katz returned to describing normal function of the body, which is breakdown of glucose. Even the hopeful student compared it to running a car without oil - necessary in an emergency, but a really bad idea for general use.
Skip forward seven or eight years, and I'm reading about some "new" diet that's becoming popular. "Hmmmm, strange. Wait a minute, no carbohydrates... Is this.... Oh my God, that must have been the name of the quack who Dr. Katz couldn't remember! Atkins!"
And so it goes. :-)
Posted by: David Reynolds on February 13, 2004 07:06 AMComments are Closed.