It’s possible to “prove” just about anything via a blizzard of citations and a few carefully-placed appeals to authority. It’s also easy to become seduced by a plausible and elegant biochemical pathway. Presto: science!

However, when formulating a hypothesis, it’s most important to constrain it by observed reality.

(This is Part II of a series. Click here for Part I.)

Empirical Evidence: “Calorie Math” Doesn’t Work

“ERS data suggest that average daily calorie intake increased by 24.5 percent, or about 530 calories, between 1970 and 2000.” (Source: “Profiling Food Consumption In America”, USDA Economic Research Service.) In absolute terms, the average American was consuming roughly 2150 “calories” per day in 1970, 2260 “calories” per day in 1980—and nearly 2700 “calories” per day in 2000.

Source: USDA ERS

Note that the shape of this curve roughly parallels the prevalence of obesity in America, which increased slowly before 1980 and took a steep upturn afterwards:

Note that the upturn in obesity coincides with the US Government’s advice to eat less fat and cholesterol, and more whole grains.

Edible fats contain roughly 3500 calories per pound. Therefore, assuming that people were close to their mythical “daily maintenance calories” in 1970, “calorie math” tells us that the average American gained approximately 800 pounds between 1970 and 2000…and has been gaining one pound per week ever since!

If “calorie math” worked, we would all look like this.

Meanwhile, back in reality, the average adult American gained approximately 19 pounds between 1971 and 2000. (Source: Mean Body Weight, Height, and Body Mass Index, United States 1960–2002, Centers for Disease Control.)

The same “calorie math” says a 19-pound gain in 30 years should require a surplus of just six calories per day. That’s nearly two orders of magnitude smaller than the observed 530 calories per day.

Yes, six calories is enough to stop the obesity crisis! All Americans have to do in order to stop gaining weight is to pull four Rice Chex out of the bowl each morning.

I blame the ones hiding under the spoon.

Clearly, “calorie math” doesn’t work.

These are back-of-the-envelope calculations, and are not meant to be exact. And I know some might be tempted to quibble about potential errors in the ERS data: keep in mind that we’re not speaking of a 12% difference, or even a 100% difference. We’re speaking of a nearly 10,000% difference between predicted and observed weight gain.

Yes, I weighed the Rice Chex myself.

Empirical Evidence: “Calorie Math” Doesn’t Work, Part II

We’ve established that the 3500-calorie rule is off by roughly two orders of magnitude for weight gain. It’s also wildly inaccurate for weight loss.

Int J Obes (Lond). 2013 Apr 8. doi: 10.1038/ijo.2013.51. [Epub ahead of print]
Can a weight loss of one pound a week be achieved with a 3500-kcal deficit? Commentary on a commonly accepted rule.
Thomas DM, Martin CK, Lettieri S, Bredlau C, Kaiser K, Church T, Bouchard C, Heymsfield SB.

Despite theoretical evidence that the model commonly referred to as the 3500-kcal rule grossly overestimates actual weight loss, widespread application of the 3500-kcal formula continues to appear in textbooks, on respected government- and health-related websites, and scientific research publications. Here we demonstrate the risk of applying the 3500-kcal rule even as a convenient estimate by comparing predicted against actual weight loss in seven weight loss experiments conducted in confinement under total supervision or objectively measured energy intake.

Their Java applet simulates the average of all the weight vs. time curves extracted from the studies they selected: you can download it here. While it doesn’t account for the differences caused by macronutrient composition (e.g. Ludwig 2012), meal timing (see below), meal composition (see below), or the host of other significant factors, you can amuse yourself by turning on “Show 3500 Calorie Rule” from the Options menu.

Clearly, “calorie math” doesn’t work.

Empirical Evidence: A “Calorie” At Dinner Does Not Equal A “Calorie” At Breakfast

Here’s a fascinating controlled study:

Obesity (Silver Spring). 2011 Oct;19(10):2006-14
Greater weight loss and hormonal changes after 6 months diet with carbohydrates eaten mostly at dinner.
Sofer S, Eliraz A, Kaplan S, Voet H, Fink G, Kima T, Madar Z.

Seventy-eight police officers (BMI >30) were randomly assigned to experimental (carbohydrates eaten mostly at dinner) or control weight loss diets for 6 months.
[…]
Greater weight loss, abdominal circumference, and body fat mass reductions were observed in the experimental diet in comparison to controls. Hunger scores were lower and greater improvements in fasting glucose, average daily insulin concentrations, and homeostasis model assessment for insulin resistance (HOMA(IR)), T-cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) levels were observed in comparison to controls.
[…]
A simple dietary manipulation of carbohydrate distribution appears to have additional benefits when compared to a conventional weight loss diet in individuals suffering from obesity.

How about that?

The officers were eating the same number of “calories”…they were even eating the same balance of protein, fat, and carbohydrate. Yet, the “carbs for dinner” group lost an additional 2.5kg (5.5 pounds) after six months.

Furthermore, this was a deeply restricted diet (1300-1500 “calories”), so we’d expect all the participants to be extremely hungry. (The Minnesota Starvation Experiment fed its volunteers more: 1600 “calories” per day.) Yet the “carbs for dinner” group rated themselves as less hungry and more sated…so real-world results, in which food intake is only restrained by one’s willpower, would be even greater.

Finally, the “carbs for dinner” crowd were healthier in all measured respects: lower abdominal circumference and fat mass, lower fasting glucose and HOMA(IR), lower LDL, higher HDL, and lower whole-body inflammation (CRP, TNF-α, IL-6). All this from a standard “healthy” high-carb diet (20% protein, 30-35% fat, 45-50% carbohydrate), tweaked so that the carbohydrates were eaten mostly at dinner!

Conclusion: a “calorie” of carbohydrate eaten for breakfast is not equal to a “calorie” of carbohydrate eaten for dinner.

According to “calorie math”, the additional weight loss would equal 107 fewer “calories” per day. Apparently you can change the number of “calories” in food just by eating it at a different time of day…

…or perhaps the concept of “calories” is flawed. (I’ll leave the additional problems this experiment poses for reward-based hypotheses of obesity as an exercise for the reader.)

Also note the dramatic alterations to the hormonal milieu: the same authors explore this in more detail in a followup study.

Nutr Metab Cardiovasc Dis. 2012 Aug 14. [Epub ahead of print]
Changes in daily leptin, ghrelin and adiponectin profiles following a diet with carbohydrates eaten at dinner in obese subjects.
Sofer S, Eliraz A, Kaplan S, Voet H, Fink G, Kima T, Madar Z.

Empirical Evidence: A “Calorie” Of Powdered Food Does Not Equal A “Calorie” Of Regular Food

Hat tip to Kindke for this excellent and well-controlled study:

Br J Nutr. 2013 Apr;109(8):1518-27. doi: 10.1017/S0007114512003340. Epub 2012 Aug 6.
Diet-induced obesity in ad libitum-fed mice: food texture overrides the effect of macronutrient composition.
Desmarchelier C, Ludwig T, Scheundel R, Rink N, Bader BL, Klingenspor M, Daniel H.

“The most striking finding was that all mice fed the different powder diets developed obesity with similar weight gain, whereas among the mice fed the pellet diets, only those given the HF and W diets became obese.”

(Note that all mice were fed ad libitum, which means they could eat as much as they wanted.)

Two instructive graphs:

Weight change on standard pelleted diets.

See? High-fat diets cause obesity! (In C57BL/6N mice genetically-engineered to quickly become obese.)

Weight change on powdered diets.

Except when you grind them all into powder—at which point all diets become equally “obesogenic”.

Another fascinating fact: the mice who became obese on the powdered chow were eating the same amount of food that kept them lean when it remained in pellet form! Yes, they were eating the same number of “calories”…

…which made them fat in powder form, but not in pellet form.

We’re not just talking about a little bit of extra fat, either: the mice got 80% heavier on the powdered food, versus 18% on the pelleted version of the same food.

Furthermore, the mice who ate the “high-fat” diet consumed 19% fewer “calories” worth of powdered food—but became just as fat as before. And the mice eating the “Western” diet also consumed 19% fewer “calories”—but became even fatter than before!

Conclusion: a “calorie” of powdered food does not equal a “calorie” of regular food—particularly when the powder is primarily carbohydrate.

Some More Observations On Desmarchelier et.al.

As Kindke notes, flour is powdered carbohydrate. So is sugar. So is almost anything that ends up packaged in a brightly-colored box…processed foods are almost entirely comprised of grains ground into powder, pressed into shape, usually doused with sugar, and baked or fried. Bread, cereal, pasta, donuts, cookies, corn chips, crackers, “instant” anything…yet another reason that Step 1 of “Eat Like A Predator” contains “Do not eat anything made with ‘flour’.”

This study also poses several problems for reward-based hypotheses of obesity. The “high-fat” diet became less “rewarding” when ground into powder, but resulted in the same weight gain. The “Western” diets came in three different flavors, but produced identical results…and all became less “rewarding” when ground into powder, yet resulted in more weight gain. And chow was apparently just as “rewarding” in powder form as in pellet form, yet caused much greater weight gain. (For a demystification of the current state of hunger science, watch my AHS 2012 presentation.)

Finally, here’s a bonus observation. Quote from the paper: “Irrespective of the food texture, the W diet induced a more severe hepatosteatosis and higher activities of serum transaminases compared with the two other diets. In conclusion, diets differing in macronutrient composition elicit specific pathophysiological changes, independently of changes in body weight. A diet high in both fat and sugars seems to be more deleterious for the liver than a HF diet.”

There’s much more—including an indictment of the entire field of obesity research, which has based much on the idea that “high-fat” diets cause obesity. Head over to Kindke’s article to read it.

Conclusions: Our Story So Far

• A calorie is not a calorie when you eat it at a different time of day.
• A calorie is not a calorie when you eat it in a differently processed form.
• Calorie math doesn’t work for weight gain or weight loss.

And we haven’t yet discussed the effects of nutrient partitioning, the mysteries of acronyms like REE, TEE, and TEF, or the myriad other ways in which a calorie is not a calorie. Click here to continue to Part III!

Live in freedom, live in beauty.

JS

(This is Part II of a series. Click here for Part I.)

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