I Tried Veganism and It Didn't Work for Me
Summary
Most vegan diet "failures" stem from inadequate calories, missing B12, sudden fiber increases, or narrow food variety — not from plant-based eating being inherently unhealthy. With proper planning, 84% dropout rates can be dramatically reduced.
Supported by 3 cited sources
Key Points
- 1The Faunalytics study (2014) — the largest survey of current and former vegetarians/vegans — found that approximately 84% of people who try a vegan diet eventually return to eating animal products.
- 2These numbers sound discouraging, but they reveal something important: most failures are not about veganism being inherently unhealthy. They are about the gap between intention and execution.
- 3Plant foods are generally lower in calorie density than animal foods.
- 4Research on the nocebo effect shows that 70-80% of symptoms reported during dietary trials are unrelated to the actual dietary intervention (Neumann et al., 2022).
Evidence Summary
Why People Struggle on Vegan Diets
The top reasons were dissatisfaction with food (32%), health concerns like fatigue (26%), social difficulties (13%), and inconvenience (13%).
The Most Common Pitfalls
Inadequate Calorie Intake
A randomized clinical trial found participants on a low-fat vegan diet spontaneously reduced calorie intake enough to lose 5.9 kg (95% CI: 5.0-6.7 kg) over 16 weeks without being asked to restrict calories (Kahleova et al., 2020, JAMA Network Open). Important caveat: this was a low-fat vegan diet specifically, not just any vegan diet, so results may not generalize to all vegan eating patterns. For someone who does not want or need to lose weight, this produces fatigue, brain fog, and weakness.
What helps: Eating calorie-dense whole foods — nuts, seeds, avocados, whole grains, dried fruit, and nut butters.
Not Supplementing B12
A systematic review found that B12 intake among unsupplemented vegans averaged just 0.24-0.49 mcg/day, compared to the recommended 2.4 mcg (Bakaloudi et al., 2021). B12 deficiency develops slowly but causes severe fatigue, neurological problems, and cognitive decline.
What helps: Supplementing with 2,500 mcg cyanocobalamin weekly, or 50 mcg daily.
Sudden Fiber Increase
A randomized controlled trial found that vegan diets significantly increased fiber intake (34.89 g/day vs. 22.79 g/day), causing substantial GI discomfort during transition (Lederer et al., 2024). Bloating and gas are common but temporary.
What helps: Transitioning gradually over 4-8 weeks. Soaking and rinsing beans, starting with smaller portions.
Narrow Food Variety
Some new vegans rely on pasta, bread, and salads without replacing protein sources. Protein needs can be met but require variety: legumes, tofu, tempeh, seitan, nuts, seeds, and whole grains.
Symptom Misattribution
Symptoms are real, but the cause may not be the diet.
Health Conditions That Make It Harder
Some conditions do require extra planning:
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IBS/FODMAP sensitivity: Many vegan protein staples are high-FODMAP, but low-FODMAP vegan diets are feasible with guidance
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Multiple food allergies: Rare combinations of soy + nut + legume allergies make it harder but not impossible
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Eating disorder history: Additional food rules can reinforce restrictive patterns; professional support is essential
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IBD during flares: Temporary modifications may be needed, though plant-based diets may benefit IBD long-term
Supporting Evidence
Based on the Faunalytics 2014 survey of over 11,000 U.S. adults. Most failures relate to planning gaps, not inherent dietary inadequacy.
Plant foods are lower in calorie density, which benefits weight loss but can cause fatigue and weakness for those who do not adjust portions.
B12 deficiency is entirely preventable with supplementation. Supplemented vegans achieve normal B12 status.
The Bottom Line
No major medical organization has identified a condition for which veganism is categorically medically impossible. However, there are circumstances where it requires significant professional support. The barriers are practical — access to variety, supplements, and guidance — and they are real.
Practical Takeaways
How to Respond with Empathy
When someone shares this experience:
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Validate first: "I believe you felt unwell. That experience is real."
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Acknowledge difficulty: "A vegan diet does require more planning, especially at first."
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Explore gently: Only if invited, discuss calorie adequacy, B12, protein variety
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Offer solutions, not guilt: Suggest a registered dietitian, practical resources
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Respect autonomy: "Whatever you decide, reducing animal products where you can still makes a difference."
Sources & Evidence
3 sources cited across 3 claims
84% vegan/vegetarian dropout rate
Cohort StudyVegan diets cause unintentional undereating
RCTUnsupplemented vegans have high B12 deficiency
Systematic Review