Misleading Media: Identical Twins Vegan vs. Omnivore Diet Outcomes

Recently this article came out:

Identical twins compared a vegan diet with meat-eating and found the vegan diet led to fat loss and more energy

Which got me thinking about how biased and misleading the media can be both in reporting and headlines, so I wanted to breakdown what is actually reported here.

From the Article:

The Turner twins, Hugo, left, and Ross, before comparing a vegan diet with an omnivorous diet in a 12-week experiment.

Overview of self-designed study design:

  • Randomized diet selection is not reported
  • Case study, n = 2, identical twins
  • Length: 12 weeks
  • Exercise: 5-6 days cardio with trainer
  • Diet: Almost isocaloric with food made by a chef delivery service (no macro/micronutrients reported)
  • Data points tracked: weight, cholesterol, muscle mass, subjective feeling, and microbiome
  • No extensive blood work was done
NameHugoRoss
DietVeganOmnivore – Varied
Starting Weight (lbs)185175
Ending Body Weight (lbs)181189
Starting Body Fat13%13%
Ending Body Fat12%15%
Muscle Mass IncreaseNo reported10lbs
Cholesterol“dropped”“consistent”
MicrobiomeDiversity decreasedDiversity decreased, but remained more consistent than Hugo’s
Subjective FeelingImproved energy later in the day and during gym session compared to before, but also notes he used to eat chips biscuits for snack which he traded for fruits and nuts   Libido dropped sharplyNone provided

Hugo states: “eating vegan forced variety”

Article reports key take-home: The twins concluded that their optimal diet is a mix of plant- and animal-based foods

— My Thoughts/Breakdown —

Game Changers has recently popularized athletes switching to a vegan diet, and the media has taken this and ran with it. That documentary is not the main topic of this post. To see a detailed review of the biases of the documentary click here: https://tacticmethod.com/the-game-changers-scientific-review-and-references/. This post is to breakdown the facts of this article vs. what is being promoted.

Although I find this research fascinating for a couple reasons, I also see the danger in how it was reported as detailed below:

  1. Twin case studies are a unique way to compare genetically identical individuals not often available in the literature. That being said it is a sample size of n=2 making extrapolation to larger populations difficult and dangerous.
  2. They aimed for an isocaloric diet to control that variable, although we are not given the macronutrient breakdowns and the fiber content, which is important for net calories and identifying changes in muscle mass between the two subjects. For example, 100 calories with 10g fiber is not all digestible and would result in lower net calories. Since vegan diets are traditionally high fiber due to the high plant content, it is likely that the vegan diet was lower net calories.
  3. Body weight is only reported for the vegan, but subtracting the 14 lbs (10lbs muscle, 4lbs fat) gained by the omnivore in the study puts his starting weight at 175 which is 10lbs lighter at the start of the study and is a significant difference.
  4. Although the headline reports body fat changes as a major benefit you can see from the results that the change in the vegan diet was 1%. From extensive work in body composition data, a 1% change in body composition is well within the area of standard area even with the most accurate machines. Additionally, Ross gained 10lbs of muscle, which is typically accompanied with small amounts of fat, explaining the increase of 2% body fat. Side note, muscle mass is an important characteristic for athletes, since muscle mass directly associated with force generation and velocity.
  5. Comprehensive blood work is not done, but they report cholesterol in the vegan diet dropping (typically seen with the increase in fiber in a diet) and the omnivore diet staying the same, although no specific numbers are reported.
  6. When comparing subjective reports the vegan diet is highlighted for increasing energy, although he admits he was eating processed snacks before and substituting fruit and nuts is a more blood sugar stable snack regardless of the rest of your diet, and more significantly he reports having decreased libido, which can be a sign of the body not producing enough testosterone which would eventually hinder performance. Dietary cholesterol is necessary to be able to produce testosterone. No subjective report was given to compare for the omnivore.
  7. Lastly, they compare microbiome reports, and although the research here is promising it is still in the beginning phases of research. Interestingly enough, both had a decrease in microbial diversity (number of bacteria species), typically associated with less resilience.

Overall you can see that although interesting, there is little evidence to support the headline that is flashed across web browsers and newspapers across the world, and more importantly, is misleading to the actual evidence that it does show. Even the subjects themselves say their ideal diet combines the best of both diets: the protein and cholesterol benefits from animal products and the variety and fiber from a vegan diet. We need to stop demonizing one side or the other. As with politics or anything, having a balance and understanding of the data is the key.