Not all “high fat” diets are high in fat enough

High fat dietary approach has been controversial for many reasons, but it has been continually mis-reported and also mis-researched.

In a Chinese randomized controlled trial, it has been found out that a low fat and high carb diet is more efficient for weight control than a high fat low carb diet is. However, there are two problems with this “finding”. First, the participants were young and healthy people, and the second: the design of the diets did not include a really very low carb ketogenic diet. The participants were randomized into low-fat diet (fat 20%, carbohydrate 66% energy), moderate diet (fat 30%, carbohydrate 56% energy) and “LCHF” diet (Wan et al., 2017). So what really was the problem? The third group nutrition ratio was: 40% fat and 46% carbohydrate. Unfortunately, this a study wtih this kind of design can’t claim that low-fat diet is better than LCHF / ketogenic diet in weight loss. The real high fat diet only works in higher percentages of fat and much lower percentages of carbs. If these two criteria are not met, this has really nothing to do with the keto / LCHF – no one can get into dietary ketosis with 40% fat : 46% carbs ratio!

High fat nutrition during pregnancy was similarly condemned by findings by a research on non-human pregnant primates:  feeding high fat chow to pregnant primates poses metabolic risks to offspring and impacts brain development and mental health. There were two groups of animals, one was fed a control diet (energy sources: protein 26.8%, fat 14.7% and carbs 58.5), the other “high fat” diet (energy sources: protein 18.4,% fat 36.6% and carbs 50.0%*) (Thompson et al., 2017). Again: the “high fat” group of animals here did not receive a ketosis inducing high fat diet, but in all senses a diet where the predominant source of energy are still the carbs. Any conclusion that a ketogenic diet during pregnancy might be detrimental for the baby can’t be drawn – ketogenic diet was not even observed.

* Please note the incorrectly calculated carb percentage. It should’ve been 44.9, according to the data in the paper.

THOMPSON, J.R. et al. 2017. Exposure to a High-Fat Diet during Early Development Programs Behavior and Impairs the Central Serotonergic System in Juvenile Non-Human Primates. Frontiers in Endocrinology, vol. 8, no. 164.

WAN, Y. et al. 2017. Effects of Macronutrient Distribution on Weight and Related Cardiometabolic Profile in Healthy Non-Obese Chinese: A 6-month, Randomized Controlled-Feeding Trial. EBioMedicine.