What about ex-vegans and health failures?
Summary
Most people who quit veganism cite convenience and social pressure, not health problems. However, genuine failure modes exist — poorly planned diets, unaddressed deficiencies, and certain health conditions can make strict veganism significantly harder for some individuals.
Key Points
- 1The largest survey of former vegetarians and vegans (Faunalytics, 2014, n=11,000+) found that the top reasons for quitting were dissatisfaction with food, social difficulty, and inconvenience — not health crises. Only about 26% cited health concerns, and these were often vague symptoms like fatigue that are commonly associated with inadequate calorie intake or B12 deficiency rather than inherent dietary failure.
- 2Real failure modes do exist and should be acknowledged honestly. The most common are: (1) not supplementing B12, leading to fatigue and neurological symptoms over months or years; (2) inadequate calorie intake, since plant foods are generally less calorie-dense; (3) insufficient protein variety, especially when relying on pasta and salads without legumes, tofu, or other concentrated protein sources; (4) sudden fiber increases causing GI distress that feels like the diet is 'not working.'
- 3Eating disorders masked as veganism are a real and serious concern. Orthorexia (obsessive focus on 'clean' eating) and anorexia can both use veganism as a socially acceptable framework for restriction. Clinicians working in eating disorder recovery sometimes recommend against strict dietary rules — including veganism — during treatment, and this is a legitimate clinical judgment.
- 4Some people have genuine health conditions that make strict veganism more challenging: severe IBS with multiple FODMAP sensitivities, combined allergies to soy, nuts, and legumes, or conditions requiring specific nutrients in forms more bioavailable from animal sources. The 'as far as possible and practicable' principle applies here.
- 5The ex-vegan narrative is amplified on social media in ways that do not reflect the population-level evidence. Individual anecdotes — no matter how vivid — do not override the positions of major dietetic organizations that well-planned vegan diets are nutritionally adequate for all life stages (Academy of Nutrition and Dietetics, 2016).
Evidence Summary
The Faunalytics study (Asher et al., 2014) remains the largest dataset on vegan/vegetarian attrition. Bakaloudi et al. (2021, Clinical Nutrition) conducted a systematic review confirming that unsupplemented vegans are at high risk of B12 deficiency (average intake 0.24-0.49 mcg/day vs. the 2.4 mcg RDA) but that supplemented vegans achieve normal status. Kahleova et al. (2020, JAMA Network Open) showed that a LOW-FAT vegan diet caused spontaneous caloric reduction averaging 5.9 kg of weight loss
Long-term adherence data on vegan diets is limited, with most intervention studies lasting weeks to months rather than years. The Faunalytics survey is self-reported and subject to recall bias. There are few studies specifically examining people who quit veganism for health reasons to determine whether their health problems were genuinely diet-related or attributable to other factors. The evidence on genetic variations affecting nutrient metabolism (e.g., BCMO1 polymorphisms affecting beta-carotene conversion) is growing but not yet sufficient to make individual-level recommendations.
The Bottom Line
The evidence suggests that most vegan diet failures are preventable with proper planning, supplementation, and gradual transition. However, dismissing all ex-vegan experiences as 'they just did it wrong' is both inaccurate and unhelpful. Some people face genuine barriers — medical, psychological, or practical — that make strict veganism significantly harder. Acknowledging this honestly, while noting that these cases do not invalidate the broader evidence base, is more persuasive than pretending every failure is user error.
Practical Takeaways
If you tried veganism and struggled: (1) check whether you were supplementing B12 and eating enough calories — these two issues account for the majority of reported symptoms; (2) consult a registered dietitian familiar with plant-based nutrition before concluding the diet itself was the problem; (3) if you have a diagnosed condition that genuinely complicates veganism, reducing animal products as far as you practically can still makes a meaningful difference; (4) any reduction in animal product consumption is better than none — flexitarianism and reducetarianism are valid approaches.