Just Read: DIETFITS and Effect of Low-Fat vs Low-Carbohydrate Diet, real food is better, is the low fat diet worse for metabolic health?

Gardner CD, Trepanowski JF, Del Gobbo LC, Hauser ME, Rigdon J, Ioannidis JPA, et al. Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion. JAMA [Internet]. 2018 Feb 20;319(7):667. Available from: http://jama.jamanetwork.com/article.aspx?doi=10.1001/jama.2018.0245

I updated the post with TG/HDL calculations and their significance, interested in others’ comments

Long anticipated study findings, previously reported in conference proceedings. I posted on the methods previously (see link below).

lipid changes, there are significant ones:

The 12-month changes in low-density lipoprotein cholesterol concentrations significantly favored a healthy low-fat diet. High-density lipoprotein cholesterol concentrations increased significantly more and concentrations of triglycerides decreased significantly more for the healthy low-carbohydrate diet group than for the healthy low-fat diet group.

Unfortunately, I couldn’t make sense of the values in Table 3 of the paper, so I ended up going to the supplemental data to review lipid and metabolic health changes. I plotted those in the attached images, click on any to see full size.

Study subjects show evidence of insulin resistance, is the low-fat diet diabetogenic?

As several recent studies have shown (including this one using Kaiser Permanente data), triglycerides and HDL may be more impactful to health in the long run than LDL-C changes.

From the paper referenced below:

The hazard ratio for having an insulin-resistant triglyceride/HDL-c ratio was 1.68 (95% CI, 1.57-1.80), compared with an insulin-sensitive ratioBertsch RA, Merchant MA. Study of the Use of Lipid Panels as a Marker of Insulin Resistance to Determine Cardiovascular Risk. Perm J [Internet]. 2015 Nov 2 [cited 2017 Oct 24];19(4):4–10. Available from: http://www.thepermanentejournal.org/issues/2015/fall/5945-insulin-resistance.html

Looking at the data, by this definition, the average TG/HDL ratio for all subjects is in the insulin resistance range, and only in the low-carbohydrate diet group does the average drop into the insulin sensitivity range.

Just Read: Challenging the role of LDL vs Insulin Resistance in predicting heart disease, via Kaiser Permanente data

This is especially interesting because

  • This is not a study of diabetes or lipid treatment
  • the study subjects are healthy, mostly white, and
  • specifically not on diabetes or lipid-lowering medications
  • Measures of liver dysfunction are not included (and they are not one of the outcomes)

Therefore, the concern is that the low-fat diet may be more diabetogenic than the low-carb one

Real Food wins, Industrialization & Genetic Testing doesn’t

This is great news. Preventing the further medicalization/industrialization of obesity, and potentially diabetes (although as stated above, this is not a study of diabetes)

We consider the differences betweenthe current findings an dthe studies cited to potentially involve diet quality beyond simply differentiating fat and carbohydrate intake. In this regard, refined grains are low in fat but considered of poor nutritional quality due to low-nutrient density relative to energy content. In contrast, vegetables are high in nutrient density,and relatively high in proportional carbohydrate content,but low in calories. Both diet groups in the current study were instructed to minimize or eliminate refined grains and added sugars and maximize intake of vegetables.

People can quibble about the definition of “low carbohydrate”

In the healthy low-fat diet vs the healthy low-carbohydrate diet, respectively, the mean 12-month macronutrient distributions were 48% vs 30% for carbohydrates, 29% vs 45% for fat, and 21% vs 23% for protein

Those proportions are not really a diabetes-remission diet

I’m cancelling my trip to Low Carb Breckenridge #LCB18. Just kidding πŸ™‚ .

As I mentioned in this post yesterday, weight loss is one dimension of diet, metabolic health is a bigger universe than that. It is good to see that there’s a place for real food in everyone’s eating trajectory. This seems to be a common theme regardless of eating preference. Remember, this is how we got here:

More from my trip to the Library of Congress and incredible US News and World Report photo collection: 1968’s Harried Housewife Preparing Convenience Foods (and how her diet was re-engineered to be carbohydrate-rich)

Citation: Gardner CD, Trepanowski JF, Del Gobbo LC, Hauser ME, Rigdon J, Ioannidis JPA, et al. on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion. JAMA [Internet]. 2018 Feb 20;319(7):667. Available from: http://jama.jamanetwork.com/article.aspx?doi=10.1001/jama.2018.0245

Post on the study design: Just Read: DIETFITS study design – Healthy Low Carbohydrate and Healthy Low Fat Diet Comparison for Weight Loss in non-diabetic humans

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