Fat-Burning Crosspoint Training: Find Your Fatmax and Boost It 15% in 6 Weeks

What Is Fatmax

As exercise intensity increases, the body’s fuel source shifts from fat to carbohydrates. Fatmax is the intensity point where the fat oxidation rate is highest.

Beyond Fatmax, although total calorie expenditure increases, the fat percentage decreases, and carbohydrates (glycogen) become the primary fuel.

Crossover Point

The crossover point refers to the intensity at which fat and carbohydrates each contribute 50% of energy. For untrained individuals, the crossover point is around 60–65% VO₂max; for well-trained endurance athletes, it can be pushed to 70–75% VO₂max.

Three Ways to Find Fatmax

Method 1: Laboratory Respiratory Gas Analysis (Most Accurate)

• Incremental exercise test
• Intensity increases every 3 minutes
• VO₂ and VCO₂ measured simultaneously to calculate RER (respiratory exchange ratio)
• The point where RER ≈ 0.85 is Fatmax
• Cost: Approximately NT$3000–6000 in Taiwan

Method 2: Heart Rate Method (Most Practical)

• Fatmax heart rate ≈ MHR × 0.70–0.75
• Example: MHR 188, Fatmax approximately 132–141
• Drawback: Individual variation can reach ±10 bpm

Method 3: RPE (Rate of Perceived Exertion) Method

• Intensity 5/10 (10 being maximal effort)
• Can hold a full conversation while riding
• Steady nasal inhale, mouth exhale rhythm
• This intensity is usually close to Fatmax

Fat Burning Rate at Fatmax

For a well-trained 70kg rider at Fatmax (approximately 70% MHR):

• Total calorie expenditure: approximately 600 kcal/h
• Fat contribution to energy: approximately 65%
• Fat burning: approximately 43 g/h

Converted, 1 hour burning 43g of fat = approximately 387 kcal.

If intensity increases by another 10% (to 80% MHR):

• Total calorie expenditure: approximately 750 kcal/h
• Fat contribution to energy: drops to 35%
• Fat burning: only approximately 29 g/h

The higher the intensity, the lower the fat-burning percentage—this is why Fatmax training is highly valued in the fat-loss community.

6-Week Fatmax Progression Plan

Goal: Push Fatmax heart rate from 65% MHR to 75% MHR

Weeks 1–2 (Building the Base)

• Monday: 60 min @ 65% MHR
• Wednesday: 60 min @ 65% MHR
• Friday: 90 min @ 65% MHR
• Saturday: 30 min @ 70% MHR (steady-state tempo)

Weeks 3–4 (Pushing Intensity Up)

• Monday: 60 min @ 70% MHR
• Wednesday: 60 min @ 70% MHR
• Friday: 90 min @ 68% MHR
• Saturday: 4 × 8 min @ 75% MHR (3 min rest)
• Sunday: 120 min @ 65% MHR (recovery long ride)

Weeks 5–6 (Consolidation and Testing)

• Monday: 60 min @ 72% MHR
• Wednesday: 60 min @ 72% MHR
• Friday: 3 × 15 min @ 76% MHR (5 min rest)
• Saturday: 90 min @ 70% MHR
• Sunday: Retest Fatmax at the end of week 6

Why Fatmax Can Be Trained Upward

• Increased mitochondrial density: Fat oxidation occurs in the mitochondria
• Increased intramuscular triglyceride (IMTG) storage: Fuel is more readily available
• Enhanced β-oxidation enzyme activity: Fatty acids enter the mitochondria more efficiently
• Upregulation of GLUT4 transporter proteins: Carbohydrate uptake efficiency improves, allowing fuel switching to occur only at higher intensities

Dietary Support (Low-Insulin Long Rides)

3 Hours Before Riding

• Low-GI carbohydrates (oatmeal, sweet potato) 30–50g
• Protein 15–20g
• Avoid sugary drinks

During Riding (Within 90 Minutes)

• Water only, no carbohydrate supplementation
• Reinforces the body’s ability to use fat

During Riding (Beyond 90 Minutes)

• Begin supplementing 20–30g of carbohydrates per hour
• Avoid hypoglycemia disrupting the training session

Precautions

• Don’t do Fatmax every day: 3–4 sessions per week is sufficient; overdoing it reduces training quality
• Cannot replace threshold/VO₂max work: High-intensity training must still be retained to maintain speed
• Menstrual cycle effects in women: Fat utilization is higher during the luteal phase; it is recommended to emphasize Fatmax training during this phase

Conclusion

Fatmax is not a “magic intensity,” but it is indeed an important foundation for fat loss and long-distance endurance. Commit to 6 weeks of focused execution, and you will find that at the same heart rate you can run faster and ride farther—that is evidence of an upgraded aerobic engine.

Related Reading

• FatMax Zone: Finding the Training Intensity for Maximum Fat Burning Rate
• Fat Oxidation During Exercise: Fatmax Intensity and Metabolic Flexibility
• Burn Fat or Burn Carbs? Understanding Carbohydrate Metabolism During Exercise and FATmax
• Maximizing Fat Oxidation During Exercise: The Science and Application of FatMax Training Intensity