Just Read: DIETFITS new analysis showing benefits for low carbohydrate over low fat diets for blood lipids – changing the focus from weight to metabolic health

2018.02.16 Metabolic Health Calculations, DIETFITS Randomized Control Trial 333
My original analyses of data not included in the main body of the DIETFITS paper, which shows evidence of poorer metabolic health among people eating a low-fat vs low-carb diet, despite the conclusion in the paper that the diets were equivalent for weight loss. See this blog post for more. 2018.02.16 Metabolic Health Calculations, DIETFITS Randomized Control Trial 333 (View on Flickr.com)

This heavily paywalled study is a more thorough analysis of something that caught my eye and was glossed over in the original publication of DIETFITS last year, which showed that weight loss was equivalent in groups of people who either ate a healthy low carbohydrate or a healthy low-fat diet.

The conclusion for some was “the diets are all the same.”

Except maybe they’re not…

The problem I noticed with DIETFITS not addressed in the main paper – worse metabolic health in the low-fat group

See: 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?

I took the time to dive into the supplemental materials where this information was (it wasn’t in the main paper) and made these pretty charts which show a visible tendency to insulin resistance and poorer lipid status (cholesterol,HDL, LDL, triglycerides) in the “healthy low fat” diet group.

So maybe “healthy low fat” wasn’t as “healthy.”

I didn’t have access to the raw data, this paper is an analysis of what I couldn’t analyze…

The focus on LDL in the original paper is not consistent with current science

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 groupGardner 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.

This is a misleading statement in my opinion because of the “favored” status given low-fat diet. This statement also invokes our profession’s laser-light focus on LDL when we now know that the overall profile (HDL, triglycerides, and more recently particle type/size) is more important for cardiovascular health.

The dogma-challenging data here – people who increased their % of saturated fat (SFA) on the low carb (LCHF) diet:

  • didn’t increase the quantity of saturated fat they ate – their overall calories decreased as well as their protein and carbohydrate intakes. This explodes the myth that an LCHF diet means eating more saturated fat.
  • didn’t significantly increase their LDL cholesterol
  • increased their HDL (not significantly)
  • significantly decreased their triglycerides

Without getting too complicated, the low-carbohydrate group did these things better than the low fat group, who did not drop their triglycerides.

The researchers showed that the drop in triglycerides in the low carbohydrate group (a good thing for health) was strongly related to the drop in carbohydrate intake, which makes low-carbohydrate superior in this case for metabolic health.

These are similar to the findings in the paper cited below, which tend to be repeatable – an overall improvement in lipid profile when lipids are looked as a group, not as a single number (kind of like what we should do in life itself):

2018.11.12 Low Carb and Low Carbon 586
A study of 10 keto-adapted athletes and 10 high-carbohydrate adapted athletes describes typical cholesterol changes seen in people who go on low carbohydrate, healthy fat (LCHF) diets. Often only one number is looked at (LDL-C) in criticizing this approach, however there are other changes that may be compensatory at the same time. It’s not known exactly why this happens or if it increases CVD risk.

Noting also from the data above that while none of the athletes (high carbohydrate and low carbohydrate) met criteria for insulin resistance, markers of insulin sensitivity (TG/HDL-C ratio and Lipoprotein insulin resistance index) were significantly better in the low carbohydrate group.

“Ketogenic diets in normal-weight and overweight non-athletes result in a moderate increase in total, LDL-C and HDL-C concentrations relative to low-fat diets. The observation that highly trained, ultra-endurance athletes consuming a very low-carbohydrate/high-fat diet exhibited a more dramatic and uniform hypercholesterolaemia is counterintuitive since high-volume exercise tends to lower total and LDL-C levels. The explanation for this paradox may involve high intake of cholesterol and saturated fat combined with high-energy demands for lipid metabolism characteristic of the keto-adapted phenotype. LC athletes who adopt a ketogenic diet may experience an expansion of their endogenous cholesterol pool during the adaptation phase of the diet, after which they maintain greater circulating cholesterol levels.”

Individual lipid measures for high-carbohydrate (n=10) and low-carbohydrate (n=10) ultra-endurance athletes. Bars represent mean±1SD. HDL-C, high-density lipoprotein-cholesterol; LDL-C, low-density lipoprotein-cholesterol. TC, total cholesterol; TG, triglyceride. Source; Creighton BC, Hyde PN, Maresh CM, Kraemer WJ, Phinney SD, Volek JS. Paradox of hypercholesterolaemia in highly trained, keto-adapted athletes. BMJ Open Sport Exerc Med [Internet]. 2018 Oct 4;4(1):e000429. Available from: bmjopensem.bmj.com/lookup/doi/10.1136/bmjsem-2018-000429 – Re-use permitted under CC BY-NC.

#LCHF #MetabolicHealth #DiabetesReversal #KetogenicDiet #DiabetesPrevention #Cholesterol #LMHR #LMHRScience

2018.11.12 Low Carb and Low Carbon 586 (View on Flickr.com)

Despite the pitch for plant-based eating, there’s no evidence here of superiority

The term “plant-based” was sprinkled throughout the paper, however it’s acknowledged that there’s no evidence here of superiority of plant-based over plant-free:

This study did not separate the analysis between plant-and animal-based saturated fat. Thus, the differential effects of plant- and animal-based sources of saturated fat on cardiovascular outcomes should be investigated further.Shih CW, Hauser ME, Aronica L, Rigdon J, Gardner CD. Changes in blood lipid concentrations associated with changes in intake of dietary saturated fat in the context of a healthy low-carbohydrate weight-loss diet: a secondary analysis of the Diet Intervention Examining The Factors Interacting with Treatment. Am J Clin Nutr [Internet]. 2019 [cited 2019 Jan 21]

“investigated further” is translated into english as “we failed to prove this” 🙂

Shifting the emphasis to weight loss (not as important) to metabolic health (more important)

The conclusion of the paper is well stated:

Specifically, these secondary analyses support shifting the focus from concern about percentage SFA intake on the overall lipid profile to instead aiming to maintain a relatively stable absolute level of saturated fat intake while focusing on improving the quality of the overall diet by incorporating more whole foods and decreasing processed carbohydrates as much as possible.Shih CW, Hauser ME, Aronica L, Rigdon J, Gardner CD. Changes in blood lipid concentrations associated with changes in intake of dietary saturated fat in the context of a healthy low-carbohydrate weight-loss diet: a secondary analysis of the Diet Intervention Examining The Factors Interacting with Treatment. Am J Clin Nutr [Internet]. 2019 [cited 2019 Jan 21]

Dislcosure: I’m in the 12% of Americans in metabolic health, and I’m not cancelling my trip to #LowCarbDenver

  • By the way, I am in the 12 %, this is as a good a time as any to state that I am on a healthy fat, low carbohydrate diet
  • I have no other personal interests or conflicts to disclose – conflict-free is the way to be (see: My Disclaimers and Disclosures)

See everyone there. I continue to love this century 🙂

Reference

Shih CW, Hauser ME, Aronica L, Rigdon J, Gardner CD. Changes in blood lipid concentrations associated with changes in intake of dietary saturated fat in the context of a healthy low-carbohydrate weight-loss diet: a secondary analysis of the Diet Intervention Examining The Factors Interacting with Treatment. Am J Clin Nutr [Internet]. 2019 [cited 2019 Jan 21]

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.