This article could easily be subtitled “The Study That Tells You Everything You Need To Know About Insulin, Blood Sugar, Carbohydrates, Satiety, And Obesity”. Yes, I admit to a degree of hyperbole—but this study is so well instrumented and controlled, and its results so informative, that I believe it’s important for everyone to read it.
PEDIATRICS Vol. 103 No. 3 March 1999, p. e26
High Glycemic Index Foods, Overeating, and Obesity
David S. Ludwig*, Joseph A. Majzoub*, Ahmad Al-Zahrani*, Gerard E. Dallal, Isaac Blanco, and Susan B. Roberts
Thanks to the American Academy of Pediatrics for making the full text of their archives freely available.
You should really click on the fulltext link above and read the study yourself, because it’s very clearly written…but as not everyone has that kind of time, I’ll cover the important parts.
The design of the study was simple.
- Take twelve obese teenage boys.
- Admit them to the research center the evening before. Feed them dinner and a bedtime snack (the same each time).
- In the morning, feed them one of three different breakfasts, each with equal caloric value but dramatically varying composition.
- Measure blood samples and subjective perception of hunger every 30 minutes.
- Feed them the same meal for lunch.
- Repeat blood and hunger measurements for the next 5 hours.
- Allow them to request food at any time after lunch. Measure when and how much they ate.
- Repeat after 1-2 weeks, until everyone’s been measured for all three meals.
The three breakfasts and lunches in question:
- “High-GI”: Instant oatmeal with 2% milk, a tablespoon of cream, and glucose plus an unspecified “artificial sweetener”. Milk was treated with lactase in order to increase GI. 64% of calories from carbohydrate, 16% from protein, 20% from fat.
- “Medium-GI”: Steel-cut oatmeal, prepared as above—but without the lactase, and with fructose instead of glucose and sweetener. Same macronutrient composition.
- “Low-GI”: Vegetable omelet made of appx. 1 whole egg and one egg white, low-fat cheese, spinach, and tomato, plus some grapefruit and apple slices. 40% carbohydrate, 30% protein, 30% fat.
All three meals contained the same number of total calories, and weighed approximately the same. (And, if anything, caloric availability would have been greater with the instant oatmeal than with the steel-cut oats.)
How “Heart-Healthy Whole Grains” Make Us Fat—In Pictures!
Now let’s look at the graphs!
“The mean area under the glycemic response curve for the high-GI meal (284 mmoles-min/L) was twice that of the medium-GI meal (141 mmoles-min/L; P < .001) and nearly fourfold that of the low-GI meal (76.6 mmoles-min/L; P < .001)."
Is anyone surprised that a big pile of high-carb oatmeal spikes blood glucose and insulin, and hammers glucagon?
Do you see the huge epinephrine (= adrenaline) spike four hours after the instant oatmeal, when the sugar hit wears off? (And the start of one an hour later, with the steel-cut oatmeal?) How do you think that makes you feel? Nervous, irritable, and desperately in need of another sugar hit?
Moving on: here’s the subjective hunger level, charted over time, after the three test breakfasts. Again, these results shouldn’t be a surprise to anyone:
Note that there is no time at which the hungriest omelet-eater was more hungry than any oatmeal-eater…and that after five hours (approximately the time between breakfast and lunch), both the instant and steel-cut oatmeal-eaters were approximately 65% hungrier than the omelet-eaters!
What do you think that means at lunchtime? It means the “heart-healthy” oatmeal breakfast will leave you ravenously hungry at lunch (if you even make it there without snacking), whereupon you’ll gorge and suffer an hour or two of “food coma”. Goodbye, afternoon!
Now here’s the punchline: the test subjects were fed the same meal for lunch as they had for breakfast. Over the next five hours, they were allowed to request a snack platter and eat all they wanted, as often as they wanted.
These results speak for themselves:
“Voluntary energy intake after the high-GI meal (5.8 megajoule [mJ]) was 53% greater than after the medium-GI meal (3.8 mJ), and 81% greater than after the low-GI meal (3.2 mJ).”
“In addition, mean time to the first meal request after lunch (2.6, 3.2, and 3.9 hours for the high-, medium-, and low-GI meals, respectively) differed between test meal groups (high GI vs low GI; P = .01; high GI vs medium GI, not significant).”
That’s not a misprint. People consumed 81% more calories during the five hours after eating instant oatmeal than after eating the same number of calories as an omelet and fruit—and 19% more calories after eating steel-cut oatmeal than after eating an omelet and fruit. (Note that the hunger curve for both kinds of oatmeal was rising precipitously at 5 hours, whereas the omelet + fruit curve flattened out. Do you ever have to work late? Is dinner always five hours after lunch?) Furthermore, the omelet-eaters took 50% longer to request any food at all.
That’s not all! A modern “heart-healthy” oatmeal breakfast, as mandated for schoolchildren by the new US government guidelines, would use skim milk and no cream (instead of 2% milk plus a tablespoon of half-and-half), driving the GI even higher and fat content even lower. A traditional* breakfast would use whole eggs, butter or coconut oil, and full-fat cheese (or ham, or bacon, or just an extra egg), driving the GI even lower and the fat content much higher! (Recall that between the apple and grapefruit, the low-fat cheese, and the egg whites, the “low-GI” omelet breakfast was still 40% carbohydrate and only 30% fat.) So real-world differences will be even greater than this experiment demonstrates.
* These days “traditional” is confined to a few ghettos called “paleo”, “primal”, or “Weston A. Price”. But less than a hundred years ago, nearly everyone who could afford real food was smart enough to eat it.
Conclusion: Eat Real Food, Not Birdseed
Do you want to be fat, constantly hungry, or both? Keep eating that birdseed. (Known to our overlords as “heart-healthy whole grains”.) The US government pays Big Agribusiness billions of dollars of our tax money each year to overproduce grain—to the point that we’re forced to put corn ethanol in our cars at a net energy loss just to get rid of the excess. Your poor health and shortened life help keep their profits high.
Do you want to be healthy, happy, and strong? Eat real food.
Live in freedom, live in beauty.
Interested in learning more? You might also enjoy my three-part series on carbohydrate addiction: Why You’re Addicted To Bread, Kicking Your Cereal Addiction, and The Myth Of "Complex Carbohydrates". Or, start with the index.
Meanwhile, you can help rescue others from being crushed under the “food pyramid” by using the buttons below.