Released in January 2025, Netflix’s documentary You Are What You Eat sparked wide discussion. It followed identical twins who changed their diets and lifestyles for eight weeks in a unique experiment designed to explore how food choices affect the body.
The programme was based on a peer-reviewed study exploring the Cardiometabolic Effects of Omnivorous vs. Vegan Diets in Identical Twins.
What are the cardiometabolic effects of a healthy vegan diet compared to a healthy omnivorous diet among identical twins during an 8-week intervention?
Evidence continues to suggest that plant-based diets may provide cardiovascular benefits due to higher consumption of:
Vegetables
Legumes
Fruits
Whole grains
Nuts and seeds
This trial set out to examine whether these benefits held up in a controlled, short-term intervention.
Type: Single-site, parallel-group, randomised clinical trial.
Participants: Healthy adult identical twins.
Groups: Vegan diet vs. Omnivorous diet.
Duration: 8 weeks.
Timeline: Enrolment from March–May 2022, final follow-up in July 2022.
Phase 1 (Weeks 1–4): Participants received all meals via nationwide delivery, guided by health educator counselling.
Phase 2 (Weeks 5–8): Participants self-prepared meals following the same structured guidelines:
Choose minimally processed foods.
Build a balanced plate (vegetables, starch, protein, healthy fats).
Maintain variety within each food group.
Data Collection:
Three 24-hour dietary recalls at baseline, week 4, and week 8.
Food intake logged with Cronometer.
Clinical measures taken at each time point after fasting.
Stool samples collected for future analysis of gut microbiome and inflammatory markers.
Compared with their omnivorous twin, participants on a vegan diet experienced:
LDL cholesterol reduction: –13.9 mg/dL
Fasting insulin reduction: –2.9 μIU/mL
Weight change: Greater loss (–1.9 kg vs. –0.29 kg)
No significant differences were observed between groups for triglycerides or HDL cholesterol.
The study found that a healthy vegan diet improved cardiometabolic outcomes compared with a healthy omnivorous diet over 8 weeks.
While the study was relatively small and short-term, it adds to evidence that diets rich in plant-based foods can improve cardiovascular health markers.
The documentary’s narrative strongly promoted vegan eating. Yet the wider question remains:
Does promoting a fully vegan narrative effectively encourage consumers to incorporate more plant-based foods — or can it backfire by alienating those who feel it’s “all or nothing”?