Gary Taubes—author of Why We Get Fat: and What to Do About It—attempts to make the argument that obesity is the result of a “fat storage defect” which carbohydrates purportedly encourage through the secretion of insulin. Taubes theory hinges on the notion that some calories (carbohydrates) are more fattening than others (protein or fat).
Three reasons why Taubes’ theory fails:
1. Taubes ignores a consistent body of literature that shows “a calorie is a calorie.” At this point there are numerous well done studies that have compared diets of varying levels of protein, carbohydrate and fat that find no statistical difference in weight loss WHEN CALORIES ARE CONTROLLED (kept at the same level for each diet type).[a],[b],[c],[d],[e],[k] Additionally, studies comparing low glycemic index (or glycemic load) diets to other weight loss diets find no difference when calories are kept at the same level for each diet type.[f] Furthermore, even when calories are not controlled any early statistical differences between diets are short-lived—dissappearing by six months.
2. Taubes’ theory ignores huge pieces of the human energy metabolism picture.[g],[h] Human energy metabolism is a complex system that constantly adjusts what substrates (carbohydrate, fat, protein or alcohol) it’s using (for energy) based both on what we provide it (eat and drink), as well as one’s current energy needs. More precisely we’re always burning a combination of these substrates, so it’s the ratio that changes.
Storing fat is the normal response to excess available energy from any substrate. However fat stores are also drawn upon between meals making the net change (in fat stores) zero over the course of a day—UNLESS energy intake has exceeded energy needs. Therefor, looking at energy balance in anything less than a 24-hour time frame is pointless.
When energy from carbohydrate or protein is taken in, the oxidation of protein and carbohydrate increases—as the body “knows” it has little ability to store either of these substrates (especially protein). At the same time, the body will preferentially store fat (hopefully for later use) as it has the unlimited ability to store fat. Likewise, since the body has no ability to store alcohol, it will also always be oxidized preferentially, even before protein or carbohydrate.
All these energy substrates are interconnected—the ingestion or oxidation of each affects the oxidation or storage of the others—in one of nature’s most elegant automatic feedback systems.
Taubes’ argument overlooks this big picture—total energy metabolism—by paying attention only to “deposits” (the storage of fat). This argument is like saying that your bank balance is only affected by deposits. If only it were so! As if that wasn’t specious enough, Taubes goes further into the weeds, essentially suggesting that $20 in five dollar bills (carbohydrate) adds more to your account (fat-deposits) than $20 in one dollar bills (protein), or $20 in ten dollar bills (fat).
This basic argument has long been the notion behind popular and fad diets of the low-carb, high-protein, and low-glycemic index approaches to weight loss.
While it is true that the Thermic Effect of Food is higher for protein than for carbohydrates or fat, those differences don’t add up to enough calories to be of practical significance, especially on reduced calorie diets.
3. Taubes’ theory would require reconsidering a law of physics. Earlier this year, a consensus statement came out of an American Society for Nutrition (ASN) conference where obesity researchers from a variety of backgrounds (biophysics, exercise science, human nutrition, physiology, etc.) formally agreed that the human body complies with the First Law of Thermodynamics. The bottom line the ASN Consensus Statement[i] translates to is that—as far as human energy metabolism is concerned—“a calorie is a calorie.” The jury isn’t out, to suggest otherwise is to suggest that a law of physics needs to be reconsidered. No serious researcher supports such nonsense.
While "a calorie is a calorie," what comprises a healthy diet is another conversation. And on that front, at least three well done studies point to higher cardiovascular risk and mortality rates for persons following indiscriminate high-protein/low carbohydrate regimes. Atkins is an example of an indiscriminate-low-carb diet, while South Beach—which emphasizes lean protein, unsaturated fats, and whole unprocessed foods—is not. Data from Harvard’s Nurses and Male Health Professionals Health Studies show that those following low-carb diets rich in PLANT proteins were 43% less likely to have died over 20-plus years of follow-up as those following low-carb diets rich in animal proteins.[j]
The Bottom line: Looking at a snapshot of metabolism (i.e. what happens only in the few hours after eating) overlooks the “rest-of-the-story.” Making claims about human metabolism based on a snapshot is like claiming to know a jigsaw puzzle picture from 2% of its pieces.
Taubes isn’t the first armchair theorist with an intelligent sounding but specious theory—and won’t be the last.
For example, as I mentioned earlier, carbohydrate oxidation automatically increases after eating carbohydrate. The same is true for protein. Not so for fat however, which is why Covert Bailey PhD (author of Fit or Fat) jumped to the conclusion that dietary fat was more fattening (than carbohydrate or protein). Bailey’s “theory” is another example of the hazards of theories based on just a couple puzzle pieces! The low-fat craze that Bailey kicked off in the 90’s didn’t solve anyone’s weight problems, and most agree at this point that the indiscriminate avoidance of (healthy) fat in favor of the indiscriminate intake of sugar and processed carbohydrates was a health boondoggle.
Despite what Taubes and other authors of popular diets would have you believe there is no magic way of eating that unlocks the mysteries of weight loss (or gain). Weight management and a healthy diet don’t require a PhD—just some common sense.
All the Best,
Additional references added: Sept. 1, 2012
For reliable information on healthy eating, and healthy weight loss, see my book The NEW Healthy Eating & Weight Management Guide.
[a] De Souza RJ, et al. Am J Clin Nutr 2012;95:614-625.
[b] Foster GD, et al. N Engl J Med 2003;348(21):2082-90.
[c] Sacks FM, et al. N Engl J Med 2009;360:859-873.
[d] Mozaffarian D, et al. Ann Intern Med 2010;143:147-57.
[e] Dansinger ML, et al. JAMA 2005;293:43-53.
[g] Stubbs R, et al. Am J Clin Nutr 1995;62:316-329.
[h] Stubbs R, et al. Am J Clin Nutr 1995;62:330-337.
[i] Hall KD, et al. Am J Clin Nutr 2012;95:989-94.
[j] Lagiou, P, et al. BMJ 2012;344:e4026.