Learn the different heart rate zones, what each one does, and how long to train in each for fat loss, fitness, and long term health.
Heart rate zones are one of the most useful tools for structuring cardio training, yet many people either ignore them or spend all their time in the wrong zone. Understanding what each zone does allows you to train with intention, recover better, and improve both performance and health outcomes.
At Kalos, we help clients combine heart rate zone training with DEXA Scan data to ensure their cardio supports fat loss, muscle retention, and long term metabolic health. Here is a simple breakdown of each heart rate zone and how much time you should spend in each one.
Heart rate zones are ranges based on a percentage of your maximum heart rate. Each zone creates a different physiological adaptation, from recovery and fat burning to endurance and peak performance.
A simple estimate for max heart rate is:
220 minus your age
Heart rate zones are typically divided into five levels.
50 to 60 percent of max heart rate
This is your easiest effort and feels extremely comfortable.
What it does:
Examples:
How long to spend here:
Zone 1 does not drive fitness improvements directly, but it helps you recover so harder sessions are more effective.
60 to 70 percent of max heart rate
This is the most important zone for long term health and fat loss.
What it does:
Examples:
How long to spend here:
Zone 2 training is strongly associated with reduced visceral fat and improved metabolic health, which is clearly visible on DEXA Scan tracking over time.
70 to 80 percent of max heart rate
This zone feels challenging but sustainable for shorter periods.
What it does:
Examples:
How long to spend here:
Spending too much time in Zone 3 can increase fatigue without providing the same fat loss or recovery benefits as Zone 2.
80 to 90 percent of max heart rate
This is hard, uncomfortable work that significantly stresses the system.
What it does:
Examples:
How long to spend here:
Too much Zone 4 work can negatively impact recovery and muscle retention, especially if nutrition and sleep are not dialed in.
90 to 100 percent of max heart rate
This is maximal effort and cannot be sustained for long.
What it does:
Examples:
How long to spend here:
Zone 5 is optional for general fitness and not necessary for fat loss or health focused training.
For most people focused on health, fat loss, and longevity, an ideal weekly balance looks like:
This structure improves cardiovascular health without excessive fatigue or muscle loss.
When combined with strength training and proper nutrition, heart rate zone training helps:
DEXA scans often show better fat loss outcomes and muscle preservation in clients who prioritize Zone 2 cardio over excessive high intensity work.
More intensity does not always mean better results.
A Kalos client struggled with fat loss despite frequent intense cardio. Their DEXA scan showed lean mass loss and minimal visceral fat reduction. After switching to three Zone 2 sessions per week and one short high intensity session, their follow up scan showed:
Training smarter made the difference.
Heart rate zones give structure and purpose to cardio training. Zone 2 should form the foundation for most people, while higher zones are used strategically to improve performance. When paired with DEXA Scan tracking at Kalos, heart rate zone training becomes a powerful tool for improving health, fat loss, and longevity without burnout.
If you are ready to take control of your health with the most accurate body composition analysis available, it is time to book your DEXA scan at Kalos. Whether you are looking to get lean, build muscle, improve performance, or optimize longevity, our advanced technology and expert guidance will help you get there.
Schedule your scan today at Kalos, your journey to data-driven fitness starts now.
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