Chris Gardner strikes again!

Weight loss on low-fat vs. low-carbohydrate diets by insulin resistance status among overweight and obese adults: a randomized pilot trial (Gardner et al., 2015)


diet compositions


Low carb diet: participants went from 230 grams/d to less than 50 for the first 3 months, then creeped up to ~80 over the next 3 months.

Will the critics say “the carbz weren’t low enough!”?  REALLY?



Background reading:
Carbs: Low vs. Lower
Insulin Resistance (includes a great video by Gardner)
Personalized Nutrition by Prediction of Glycemic Response

In brief, the one-size-fits-all diet theory is #fail.

Don’t be tied down to one approach; different #contexts require different approaches, and both can change over time.

On to the new study:

At baseline, patients were divided into insulin sensitive & resistant groups based on insulin levels (AUC) during an oral glucose tolerance test.  Then those groups were assigned to either a low fat or low carb diet.  There were four groups, three time points (baseline, 3 months, and 6 months).


To make a long story short, insulin sensitive patients randomized to the low fat diet lost about 20% more weight than those randomized to low carb.  Read that sentence again (just the part in bold).


weight loss by diet and insulin status


Insulin sensitive dieters lost more weight on a high carb diet than a low carb diet (10.4 vs 8.6 kg).  Insulin resistant dieters lost more weight on low carb (9.6 vs 7.4 kg).  Notably, of all four groups, the most weight was lost on a high carb diet (10.4 kg) despite low carbers consistently getting more protein.

Don’t be a science denier!

Body comp assessment would’ve been nice, but whatevs…



weight loss plot


Was there a lot of overlap? yes (EVERYONE lost weight)

Was there statistical significance? no, except  metabolic parameters improved more so in people assigned to the insulin-appropriate diet (ie, LC for IR, LF for IS).

Are these data meaningful? YES


I say this because the differences are very close to the magnitude we’d expect in these populations.  Insulin sensitive dieters lost 20% more weight if they were assigned to a low fat diet, but they still lost weight on low carb…  we wouldn’t expect insulin sensitive dieters to gain weight on a low carb diet, just lose a little less because it’s not optimal in this #context.


Diet chart


Are there a million other factors involved here?  YES.  Insulin sensitivity  is only one of ’em, but a pretty good starting point.

Theoretical scenario: a sedentary, obese insulin resistant patient starts off on LC and is initially successful.  They start exercising and focusing on sleep quality, insulin sensitivity improves (ie, new #context)... but weight loss stalls in many of these people.  Maybe at this point they would benefit more by switching the focus from strict LC to monitoring other things, like calorie or fat intake (ie, to match the new #context) –> progress resumes.


Don’t be tied down to one approach; different #contexts require different approaches, and both can change over time.


That’s all, for now.



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calories proper


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