The study was constructed to examine the hypothesis that genotype and insulin resistance patterns would dictate the best weight-loss diet at the individual level. The theory suggested that people with high-levels of insulin resistance (type 2 diabetics in the extreme) would lose weight more effectively on a low-carb diet, whereas others who are insulin sensitive would fare better with a low-fat approach. This study, the largest and most rigorous to date, not only failed to confirm the hypothesis, it went a step further. It suggests that both diets were essentially equivalent, and that this wasn’t affectedby either genotype or insulin sensitivity. Another powerful conclusion emerged, however. As part of the study method, all 600 participants were instructed to focus on:

• Maximizing vegetable intake.
• Minimizing added sugar, refined flour, and trans (but not all) fat.
• Emphasizing whole, minimally processed foods prepared at home when possible.

Most importantly, there were no controls on calories. The diet was completely centered on what to eat, not how much (to the apparent relief of the participants). And most everyone lost weight –an average of 13 pounds. This is a shot over the bow of a massive calorie-counting diet industry, as well as the producers of highly processed food. The stakes (or maybe the steaks) for these results are high, and there will no doubt be many challenges and conflicting opinions in the coming months. One final note – there are kudos due to the researchers on this study. Although the study completely failed to confirm their hypothesis, they followed the data to another conclusion that may be even more impactful. This is an example of how science is supposed to work.

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This article was recommended by Ken Smith, Senior Research Scholar, Director of the Mobility Division and Design Challenge Leader at the Stanford Center on Longevity.