Two recreational cyclists on plant-based diets completed an incredible 30-day, 4,300-kilometer ride across Canada. Researchers carefully tracked what they ate and how much energy they burned to understand how plant-based athletes can fuel extreme endurance events. The cyclists ate significantly more food during the ride—especially protein—and their bodies adapted remarkably well. The male cyclist even built muscle while losing fat. This research shows that plant-based diets can support ultra-endurance athletes, but they need to eat enough food and pay special attention to getting enough protein.

The Quick Take

  • What they studied: Can plant-based athletes successfully complete extreme endurance events like a month-long cross-Canada cycling journey, and how much food do they need to eat?
  • Who participated: Two recreational cyclists—a 41-year-old man and a 38-year-old woman—both eating plant-based diets, who rode bikes across Canada for 30 consecutive days
  • Key finding: Both cyclists stayed healthy and maintained their body weight despite burning enormous amounts of calories. They increased their food intake by 400-760 calories per day, with especially high protein intake. The male cyclist actually gained muscle while losing fat during the ride.
  • What it means for you: Plant-based diets can support extreme athletic endurance events if athletes eat enough food and get adequate protein. However, this is based on just two people, so individual needs may vary. Anyone attempting similar activities should work with a nutrition expert.

The Research Details

This study followed two real cyclists through an actual 30-day, 4,300-kilometer ride across Canada. Before and after the ride, researchers measured how many calories each cyclist burned at rest using a special room that tracks energy expenditure. During the first and last weeks of the ride, the researchers used a technique called “doubly labeled water”—where cyclists drink water with special tracers—to measure exactly how many calories they burned during their daily activities. The cyclists kept detailed food records using scales, written notes, and photographs to document everything they ate.

The researchers also measured body composition changes using deuterium dilution, a method that determines how much of the body is fat versus muscle. This comprehensive approach allowed the team to create a complete picture of energy balance—comparing calories burned to calories consumed—throughout the entire journey.

This type of detailed case study is valuable because it captures real-world conditions that are impossible to replicate in a laboratory. Ultra-endurance cycling creates extreme physiological demands, and studying actual athletes during real events provides insights that controlled experiments cannot.

Understanding how plant-based athletes fuel extreme endurance events is important because plant-based diets are becoming more popular, but there’s limited research on whether they can support the highest levels of athletic performance. This study provides practical evidence that plant-based diets can work for ultra-endurance athletes, which helps athletes and coaches make informed decisions about nutrition strategies.

This study has important strengths: it used multiple precise measurement methods, tracked athletes through a real-world event, and collected detailed dietary information. However, it has significant limitations: only two participants means the findings may not apply to other athletes, individual differences are large, and we cannot know if these results would be the same for other plant-based cyclists. The small sample size means we should view these findings as interesting observations rather than definitive proof.

What the Results Show

Both cyclists successfully completed the 30-day, 4,300-kilometer journey while maintaining stable body weight, which is remarkable given the extreme energy demands. Early in the ride, they averaged cycling 154.8 kilometers per day, which decreased to 118.2 kilometers per day by the end—a normal pattern as fatigue accumulates during ultra-endurance events.

The most striking finding was how the cyclists’ bodies adapted differently. The male cyclist lost 2.3 kilograms of fat while gaining 1.4 kilograms of muscle—essentially trading fat for muscle despite the extreme physical stress. The female cyclist maintained more stable body composition throughout. Both cyclists significantly increased their food intake, with the female eating an additional 421 calories per day and the male eating an additional 761 calories per day compared to their normal diets.

Protein intake was notably high for both cyclists, exceeding 2.3 grams per kilogram of body weight daily. This high protein consumption likely supported the muscle maintenance and building observed, particularly in the male cyclist. The total energy expenditure (calories burned) increased substantially in the female cyclist (+683 calories per day) but remained relatively stable in the male, suggesting their bodies adapted differently to the extreme demands.

Both cyclists maintained very high physical activity levels throughout the ride, with measurements ranging from 3.71 to 4.11 for the female and 3.76 to 3.94 for the male. These numbers indicate they were burning roughly 4 times more calories than they would at complete rest—an extraordinary level of activity sustained for 30 consecutive days.

The research revealed important details about how plant-based athletes can meet their nutritional needs during extreme endurance events. Both cyclists successfully obtained adequate protein from plant-based sources, suggesting that plant-based diets can provide sufficient protein for ultra-endurance athletes when food intake is high enough. The cyclists’ resting energy expenditure—calories burned at complete rest—changed differently between the two athletes, indicating individual variation in how bodies adapt to extreme physical stress. The decrease in daily cycling distance over the 30 days (from 154.8 to 118.2 km/day) reflects normal fatigue accumulation, but both cyclists remained capable of completing substantial daily distances throughout the entire journey.

This research adds to a growing body of evidence suggesting that plant-based diets can support high-level athletic performance. Previous studies have shown that plant-based athletes can compete successfully in various sports, but detailed case studies of ultra-endurance events on plant-based diets are relatively rare. This study confirms that with adequate calorie and protein intake, plant-based nutrition can sustain extreme endurance activities. The findings align with general sports nutrition principles showing that adequate energy and protein intake are critical for athletic performance, regardless of diet type.

This study examined only two cyclists, so the findings may not apply to other plant-based athletes with different body types, ages, or training backgrounds. Individual differences in how bodies respond to extreme exercise are large, and what worked for these two cyclists might not work identically for others. The study doesn’t include a comparison group of non-plant-based cyclists doing the same ride, so we cannot directly compare how plant-based diets perform against other dietary approaches. Additionally, both cyclists were experienced recreational athletes, so the findings may not apply to less-trained individuals. The study also doesn’t address potential long-term health effects or recovery after the ride, focusing only on the 30-day period itself.

The Bottom Line

Plant-based diets appear to support ultra-endurance cycling when athletes: (1) eat enough total calories—likely 400-760 additional calories per day during extreme endurance events, (2) consume adequate protein, aiming for more than 2.3 grams per kilogram of body weight daily, and (3) maintain consistent training and nutrition practices. These recommendations have moderate confidence because they’re based on two successful case studies but need confirmation in larger research studies. Athletes should work with a sports nutritionist to develop personalized plans, as individual needs vary significantly.

Plant-based athletes considering ultra-endurance events should pay attention to these findings, as they demonstrate that plant-based diets can support extreme athletic performance. Coaches and nutritionists working with plant-based athletes will find this research valuable for understanding real-world nutrition strategies. However, these findings apply specifically to experienced recreational cyclists and may not directly apply to other sports or less-trained athletes. People with medical conditions should consult healthcare providers before attempting extreme endurance activities.

The body composition changes observed in this study occurred over 30 days of continuous extreme exercise. For typical athletes doing normal training, changes would likely occur more slowly—typically over weeks to months. The cyclists’ ability to maintain performance and body weight suggests that proper nutrition strategies can support adaptation even during extreme stress, but individual timelines for seeing benefits will vary.

Want to Apply This Research?

  • Track daily calorie intake and protein consumption (in grams per kilogram of body weight) during training periods, comparing intake to actual energy expenditure. For endurance athletes, aim to log: total calories consumed, protein grams, and daily exercise duration/intensity to identify personal energy balance patterns.
  • If training for endurance events on a plant-based diet, use the app to set daily protein targets (2.3+ grams per kilogram of body weight) and monitor whether you’re meeting calorie needs. Create meal plans featuring plant-based protein sources like legumes, tofu, tempeh, nuts, and seeds, and log meals with photos to ensure adequate intake during training.
  • Establish a baseline of normal calorie and protein intake, then track changes during increased training periods. Monitor body weight weekly and note energy levels and performance metrics. For long-term endurance training, periodically reassess protein and calorie needs as training volume changes, using the app to identify patterns between nutrition intake and athletic performance.

This research describes two individual case studies and should not be considered definitive medical or nutritional advice. Plant-based diets can support athletic performance, but individual nutritional needs vary significantly based on age, body composition, training experience, and health status. Anyone considering extreme endurance activities or making significant dietary changes should consult with a healthcare provider and registered sports nutritionist. This study does not address potential health risks or long-term effects of extreme endurance activities. Always seek professional medical guidance before beginning new exercise programs or making major dietary changes.