AI 速览
- Zone 2 endurance riding burns more FAT (as a percentage of calories); higher intensity burns more TOTAL calories. For weight loss, total calories matter most — but Zone 2 is sustainable for hours (more total calorie burn) and doesn't trigger the compensatory eating that hard intervals do
- The 'exercise only' approach fails: you can't out-ride a bad diet. A 1-hour ride burns ~500–700 kcal; that's one muffin. Sustainable weight loss requires a dietary calorie deficit (300–500 kcal/day) PLUS regular riding
- The common mistake: 'earning' food with riding. 'I rode 50 miles, I deserve a big dinner' — this perfectly cancels the calorie burn. Track your intake for 2 weeks to see how much you're actually eating
- Power-to-weight ratio: losing 3 kg of body fat improves climbing by ~20 W equivalent. For riders who climb, weight loss is the single best performance upgrade — cheaper than any equipment
/ 01
The calorie math
Fat loss requires a calorie deficit: consuming fewer calories than you burn. Cycling increases the 'burn' side, but the 'consume' side (diet) is where most riders fail. A 1-hour moderate ride burns ~500–700 kcal (for a 70 kg rider). A single restaurant muffin is 500 kcal. You can't out-ride a bad diet.
Sustainable deficit: 300–500 kcal/day below maintenance. This produces ~0.3–0.5 kg (0.7–1 lb) of fat loss per week — slow enough to preserve muscle and sustainable enough to maintain. Aggressive deficits (>500 kcal/day) cause muscle loss, metabolic adaptation (your body slows its metabolism), and rebound weight gain.
/ 02
Zone 2 vs intervals — which burns more fat?
The 'fat-burning zone' (Zone 2) burns a higher PERCENTAGE of fat — but lower-intensity exercise also burns fewer total calories. At higher intensity, you burn more total calories (and more total fat, even though the PERCENTAGE is lower).
For weight loss, the practical answer: Zone 2 is better because (1) you can ride for 3–5 hours (massive total calorie burn), (2) it doesn't trigger compensatory eating (you're not ravenous after an easy ride, unlike after hard intervals), and (3) it builds the aerobic base that makes your body more efficient at burning fat at all intensities. Ride Zone 2 for volume; add 1–2 interval sessions per week for fitness (not for weight loss).
The fat-burning debate, settled. Both burn fat; the best approach is the one you can sustain.
| Approach | Calories/hour | Fat % of calories | Total fat burned | Sustainability |
|---|---|---|---|---|
| Zone 2 (endurance) | 400–600 | 60–70% | Higher (over many hours) | High — can ride for hours |
| Threshold/VO2 | 700–1000 | 30–40% | Moderate (shorter duration) | Low — 1 hour max |
/ 03
The compensatory eating trap
The #1 reason cyclists don't lose weight despite riding 10+ hours a week: compensatory eating. Exercise increases appetite (your body wants to replace the burned calories), and cyclists are notorious for 'earning' their food: 'I rode 100 km, I deserve a big meal and a beer.' The result: calorie intake rises to match calorie expenditure, and weight doesn't change.
The fix: track your food intake (MyFitnessPal, Cronometer, or a food journal) for 2 weeks. Not to diet — just to see how much you're actually eating. Most cyclists are shocked to discover they eat 500–1000 kcal more on riding days than on rest days. Awareness is the first step; the second step is eating the same amount on riding days as on rest days (the calorie deficit comes from the riding, not from eating less).
/ 04
Fasted riding — does it work?
Fasted riding (riding before breakfast, in a fasted state) is popular for fat loss. The theory: with low glycogen, your body burns a higher percentage of fat. The reality: fasted riding DOES increase fat oxidation during the ride, but it doesn't increase total fat loss over 24 hours (your body compensates by burning more carbohydrate later in the day).
The practical take: fasted Zone 2 rides (under 2 hours, easy pace) are fine and may improve fat-adaptation. But they're not a weight-loss shortcut — the calorie deficit from the ride is the same whether you eat before or not. And fasted hard riding (intervals without eating) impairs performance and recovery. If you ride fasted, keep it easy, keep it under 2 hours, and eat normally afterward.
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