# You Are What You Eat: A Twin Experiment
*You Are What You Eat: A Twin Experiment* is a four-episode Netflix documentary series released on January 1, 2024, that follows pairs of adult identical twins taking part in a Stanford University randomized trial comparing vegan and omnivorous diets over eight weeks.[1](https://www.rottentomatoes.com/tv/you_are_what_you_eat_a_twin_experiment/s01) • [2](https://news.stanford.edu/stories/2024/01/qa-christopher-gardner-featured-netflixs-eat) Directed by Louie Psihoyos and produced through OPS Productions, the series weaves the trial's results together with segments on animal agriculture, environmental impacts, and plant-based food innovation.[1](https://www.rottentomatoes.com/tv/you_are_what_you_eat_a_twin_experiment/s01) • [3](https://www.themilkhaus.com/project/youarewhatyoueat/)
| Key fact | Detail |
|---|---|
| Format | Four-episode Netflix limited documentary series, released January 1, 2024; rated TV-MA[1](https://www.rottentomatoes.com/tv/you_are_what_you_eat_a_twin_experiment/s01) |
| Director | Louie Psihoyos, produced by OPS Productions[1](https://www.rottentomatoes.com/tv/you_are_what_you_eat_a_twin_experiment/s01) • [3](https://www.themilkhaus.com/project/youarewhatyoueat/) |
| Underlying study | Stanford Twins Nutrition Study (TwiNS): 22 pairs of identical twins randomized to a healthy vegan or healthy omnivorous diet for 8 weeks[4](https://med.stanford.edu/nutrition/research/completed-studies/twins.html?tab=proxy) |
| Primary findings | Both groups improved, but the vegan twins showed greater LDL cholesterol reductions, more weight loss, and drops in fasting insulin that the omnivores did not[5](https://time.com/6551606/is-plant-based-diet-healthier-you-are-what-you-eat/) |
| Adherence | 21 of the 22 twins assigned the vegan diet stayed on it for all eight weeks[5](https://time.com/6551606/is-plant-based-diet-healthier-you-are-what-you-eat/) |
| Featured participants | The series follows four sets of twins, including chefs Pam and Wendy Drew of San Francisco's Amawele's South African Kitchen[6](https://www.axios.com/local/san-francisco/2024/01/12/netflix-you-are-what-you-eat-vegan) |
## The Stanford twin study
The series is built around the Twins Nutrition Study (TwiNS), led from the Stanford Prevention Research Center by Christopher Gardner, a professor who has spent more than 30 years at Stanford and provided dietary advice to participants during the trial.[2](https://news.stanford.edu/stories/2024/01/qa-christopher-gardner-featured-netflixs-eat) • [6](https://www.axios.com/local/san-francisco/2024/01/12/netflix-you-are-what-you-eat-vegan) The randomized clinical trial enrolled 22 pairs of healthy adult identical twins and assigned one twin from each pair to a vegan diet and the other to an omnivorous diet for eight weeks, using the twin design to control for genetics, shared household, and similar lifestyles.[2](https://news.stanford.edu/stories/2024/01/qa-christopher-gardner-featured-netflixs-eat) • [7](https://pmc.ncbi.nlm.nih.gov/articles/PMC12513280/)
Participants were recruited primarily from the Stanford Twin Registry between March and April of 2022, along with other twin registries including Netflix's pre-recruited participants interested in a documentary on vegan diets. One pair dropped out at week 4, leaving 42 participants in the analysis.[7](https://pmc.ncbi.nlm.nih.gov/articles/PMC12513280/) • [8](https://bmcmedicine.biomedcentral.com/counter/pdf/10.1186/s12916-024-03513-w) Both groups were instructed to eat high-quality diets under four principles: minimally processed foods, well-balanced meals of vegetables, starch, protein, and healthy fats, variety within each food group, and respect for individual preferences.[7](https://pmc.ncbi.nlm.nih.gov/articles/PMC12513280/)
For the first four weeks the twins ate meals supplied by the researchers before transitioning to cooking their own meals.[6](https://www.axios.com/local/san-francisco/2024/01/12/netflix-you-are-what-you-eat-vegan) Throughout the eight weeks, everyone ate a diet rich in fruits, vegetables, whole grains, and legumes and low in sugars and refined starches; one twin in each pair ate only plant-based foods while the other also ate chicken, fish, eggs, and dairy.[5](https://time.com/6551606/is-plant-based-diet-healthier-you-are-what-you-eat/) Both groups saw improvements in their cholesterol levels and modest reductions in weight, but those trends were more dramatic among the vegan twins, whose average fasting insulin levels, a marker of cardiometabolic health, dropped while the omnivores' did not.[5](https://time.com/6551606/is-plant-based-diet-healthier-you-are-what-you-eat/) Reporting on the study also noted benefits including increased healthy gut bacteria and decreased inflammation.[6](https://www.axios.com/local/san-francisco/2024/01/12/netflix-you-are-what-you-eat-vegan) Gardner summarized the result by saying it "suggests that anyone who chooses a vegan diet can improve their long-term health in two months," adding that following a vegan diet may not be as difficult as many people imagine, since 21 of the 22 twins assigned to that eating plan stuck with it for all eight weeks.[5](https://time.com/6551606/is-plant-based-diet-healthier-you-are-what-you-eat/)
## What the series covers
The four episodes track the experiment chronologically. Episode 1 introduces the twins joining the study and their assignment to plant-based or omnivorous diets; episode 2 follows the start of the diets alongside segments on dietary guidelines; episode 3 covers the shift to home cooking and plant-based alternatives to animal products; and episode 4 reveals the study results to the twins, covering weight, gut and brain health, and a growing movement in the food industry.[1](https://www.rottentomatoes.com/tv/you_are_what_you_eat_a_twin_experiment/s01)
Beyond the trial itself, the series compares body composition, the epigenome or "biological clock," the gut microbiome, and the brain before and after the eight weeks.[9](https://www.youtube.com/watch?v=2doLMJy0JKs) A follow-up analysis of TwiNS published in BMC Medicine examined the 8-week change in [DNA methylation](https://www.edgepedia.org/dna-methylation) (chemical tags on DNA that alter gene activity without changing sequence) profiles from baseline, the basis of the epigenetic comparisons shown in the series.[8](https://bmcmedicine.biomedcentral.com/counter/pdf/10.1186/s12916-024-03513-w) The production also used animation, developed with the studio Milkhaus, working directly with a scientist to translate complex scientific concepts such as methylation and microbiome data into visuals for a general audience.[3](https://www.themilkhaus.com/project/youarewhatyoueat/) The series also traces why people eat as they do, examines lesser-known aspects of the agricultural industry, and explores how both affect the Earth.[10](https://dirco.gov.za/wp-content/uploads/2024/06/Ubuntu-32-web-version-lr.pdf)
## Reception and criticism
The series drew a mixed reception. Reviewers generally accepted the underlying trial as a valuable contribution showing cardiometabolic advantages of a healthy vegan diet, and noted that the twin design controls the genetic factor that is usually difficult to manage in nutrition research; one dietitian review described the docuseries as an accessible resource for the general public to engage with diet, health, and sustainability.[11](https://www.nautilusplus.com/review-of-the-netflix-documentary-you-are-what-you-eat-a-twin-experiment/) • [12](https://www.skysrootednutrition.com/blog/registered-dietitian-review-netflix-documentary-you-are-what-you-eat)
Critics focused on the gap between the documentary and the study. Common Sense Media describes the series as decidedly pro-vegan and points out that it glosses over the fact that the director of the Twins Nutrition Study runs a plant-based initiative and that the study was funded by the Vogt Foundation, with additional support from Stanford's Clinical and Translational Science Award and the [National Heart, Lung, and Blood Institute](https://www.edgepedia.org/national-heart-lung-and-blood-institute).[13](https://www.commonsensemedia.org/tv-reviews/you-are-what-you-eat-a-twin-experiment) • [16](https://med.stanford.edu/news/all-news/2023/11/twin-diet-vegan-cardiovascular) A Skeptical Inquirer review argued that the series selectively highlights vegan-supporting data while giving little attention to countervailing results, and relies on emotionally charged detours into factory farming, food deserts, and climate change.[14](https://skepticalinquirer.org/2025/04/are-you-what-you-eat-science-vs-tv-series/) Rotten Tomatoes' critics' consensus cautions that the series "shouldn't be a source of medical or nutritional advice, but it may get you thinking more about some of the foods you're consuming."[1](https://www.rottentomatoes.com/tv/you_are_what_you_eat_a_twin_experiment/s01) The American Institute for Cancer Research framed the show as a reason for viewers to sharpen their media literacy, science, and critical thinking skills when consuming documentary content about nutrition research.[15](https://www.aicr.org/resources/blog/entertainment-or-education-reviewing-the-netflix-docuseries-on-the-stanford-twin-study/)
## References
1. [You Are What You Eat: A Twin Experiment: Limited Series, Rotten Tomatoes](https://www.rottentomatoes.com/tv/you_are_what_you_eat_a_twin_experiment/s01)
2. [Christopher Gardner on Netflix's 'You Are What You Eat', Stanford Report](https://news.stanford.edu/stories/2024/01/qa-christopher-gardner-featured-netflixs-eat)
3. [You Are What You Eat, Milkhaus](https://www.themilkhaus.com/project/youarewhatyoueat/)
4. [TwiNS, Stanford Nutrition](https://med.stanford.edu/nutrition/research/completed-studies/twins.html?tab=proxy)
5. [Is Eating a Plant-Based Diet Better for You?, Time](https://time.com/6551606/is-plant-based-diet-healthier-you-are-what-you-eat/)
6. [New Netflix show chronicles Stanford study on vegan diets, Axios](https://www.axios.com/local/san-francisco/2024/01/12/netflix-you-are-what-you-eat-vegan)
7. [Diet Quality and Comparison of Plant-Based Versus Omnivore Diets in Identical Twins: A Secondary Analysis of the Twins Nutrition Study (TwiNS), PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC12513280/)
8. [Unveiling the epigenetic impact of vegan vs. omnivorous diets on aging, BMC Medicine](https://bmcmedicine.biomedcentral.com/counter/pdf/10.1186/s12916-024-03513-w)
9. ["You Are What You Eat: A Twin Experiment", WGN News, YouTube](https://www.youtube.com/watch?v=2doLMJy0JKs)
10. [South African twins star in fascinating food Netflix documentary, Ubuntu (DIRCO)](https://dirco.gov.za/wp-content/uploads/2024/06/Ubuntu-32-web-version-lr.pdf)
11. [Review of the Netflix documentary "You Are What You Eat: A Twin Experiment", Nautilus Plus](https://www.nautilusplus.com/review-of-the-netflix-documentary-you-are-what-you-eat-a-twin-experiment/)
12. [Registered Dietitian's Review of Netflix Documentary You Are What You Eat](https://www.skysrootednutrition.com/blog/registered-dietitian-review-netflix-documentary-you-are-what-you-eat)
13. [You Are What You Eat: A Twin Experiment, Common Sense Media](https://www.commonsensemedia.org/tv-reviews/you-are-what-you-eat-a-twin-experiment)
14. [Are You What You Eat? Science vs. TV Series, Skeptical Inquirer](https://skepticalinquirer.org/2025/04/are-you-what-you-eat-science-vs-tv-series/)
15. [Entertainment or Education? Reviewing the Netflix Docuseries on the Stanford Twin Study, American Institute for Cancer Research](https://www.aicr.org/resources/blog/entertainment-or-education-reviewing-the-netflix-docuseries-on-the-stanford-twin-study/)
16. [Twin research indicates that a vegan diet improves cardiovascular health](https://med.stanford.edu/news/all-news/2023/11/twin-diet-vegan-cardiovascular)
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*Initially written Sep 17, 2026 · Reviewed: Oct 25, 2026 · Edited: Oct 11, 2026; Oct 15, 2026; Oct 25, 2026 · Last review: Oct 25, 2026*
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