Way back when Taubes’ Good Calories, Bad Calories: Fats, Carbs, and the Controversial Science of Diet and Health came out, he proposed an alternative hypothesis for obesity; essentially, that carbs drive insulin and insulin both inhibits the release of fat from storage and drives additional fat storage. He also criticized the obesity research field and Dr. Kevin Hall described it this way in a guest post on Dr. Yoni Freedhoff’s blog last year.
In a 2010 blog post, journalist Gary Taubes berated nutrition scientists for not understanding the seemingly simple concept of controlling diet variables. He chastised the field for altering multiple diet components at once and said that controlling variables is something that even
“school children are supposed to understand”
The failure of nutrition scientists to understand this basic concept
“has led to what may be another of the great misconceptions in modern nutrition research”
Mr. Taubes then exposes the horrendous misconception:
“carbohydrate-restricted diets are ‘valuable tools’ in the arsenal against overweight and obesity, but they’re just one of the dietary tools.”
Why was such a seemingly reasonable statement proclaimed to be a “great misconception”? Because, in Mr. Taubes’ view, the carbohydrate-insulin theory implies
“that the only meaningful way to lose fat … is by reducing the amount of carbohydrates consumed.” [bold mine KH.]
Doubling down on this claim in his most recent book Why We Get Fat, Mr. Taubes states that
“any diet that succeeds does so because the dieter restricts fattening carbohydrates…Those who lose fat on a diet do so because of what they are not eating – the fattening carbohydrates.”
To his credit, however, Taubes did propose ways of testing his alternative hypothesis and eventually, he teamed up with Dr. Peter Attia to co-found the Nutrition Science Initiative (NuSI), creating a vehicle whereby they could raise the funds and assemble researchers to test this Alternative Hypothesis, described here.
Current research and public health policy on obesity is largely based on the hypothesis that the fundamental cause of the condition is an energy imbalance between calories consumed and expended. By this hypothesis, the interaction between diet and body fat is determined by the caloric content of the foods consumed, while the macronutrient content of the diet (the proportion and type of carbohydrates, fats, and protein) has no meaningful effect. This is often summed up by the assertion that “a calorie-is-a-calorie,” shorthand for the hypothesis that a calorie’s worth of protein has an equivalent effect on the accumulation and storage of fat in the human body (on “adiposity”) as does a calorie of carbohydrate or a calorie of fat. An alternative hypothesis is that the macronutrient composition of the diet influences adiposity through its effect on the hormones that regulate uptake of fat (technically “fatty acids”) by fat cells and their subsequent mobilization and use for fuel (that is, oxidation).
So, well, the study is complete, not published yet, but Dr. Kevin Hall, the principal investigator, was interviewed yesterday by Dr. Yoni Freedhoff on day one of the ongoing International Conference on Obesity.
Some money quotes:
“The loss of fat mass slowed down on a low-carb, high-fat diet.”
“…it took the full 28 days of a ketogenic diet to lose the same amount of fat as was lost in the first 15 days of the normal carbohydrate diet.”
Dr. Hall’s conclusion: no metabolic advantage to a ketogenic diet. Carb-Insulin theory of obesity falsified.
So, it looks like we’re back to plain old caloric restriction to lose weight. And in that vein, then what’s most important is the diet you can stick with. So, if you can more easily or enjoyably adhere to a low-carbohydrate diet in the face of forced caloric restriction over, say, a high-carbohydrate, low-fat diet, then the LC diet is best for you, even if fat loss is more efficient on the latter diet.
Hopefully when the study is published in the near future it will provide clarity and some degree of consolation on the part of low carbohydrate and ketogenic diet advocates. Gary and many others have been pounding the pulpit for years saying ‘just test it, and do it right!’ Well it appears that’s now been done per Gary / NuSI’s own specifications—including a highly controlled metabolic ward setting—and the data simply do not come even close to suggesting that there’s a thing more worth looking at in terms of the “Alternative Hypothesis.”
I won’t be holding my breath that this is the end of it, however.