Zone 2 Cardio for Fat Loss: Heart-Rate Zones Explained

What is zone 2 cardio?

Zone 2 cardio is low-intensity, continuous aerobic exercise: a brisk walk, an easy cycle or a slow jog you can keep up for 30 to 60 minutes while breathing a little harder than normal. There is no single official definition, and the three common ones measure different things, which is why two apps can give you different zone 2 numbers.

The physiological definition is the one researchers use. A 2025 narrative review in Sports Medicine by Storoschuk and colleagues describes zone 2 training as "low-intensity exercise below the lactate threshold", meaning the point where lactate starts to build up in the blood. Finding that point properly takes a lab test with blood samples or breath gas analysis.

The heart-rate definition is the one on your watch. Polar's published five-zone scheme puts zone 1 at 50–60% of maximum heart rate, zone 2 at 60–70%, zone 3 at 70–80%, zone 4 at 80–90% and zone 5 at 90–100%. These percentages are a convenient convention, not your measured lactate threshold.

The talk test needs no equipment. A 2022 Sports Medicine review of subjective intensity methods (Bok, Rakovac and Foster) found that the talk test appears to be a valid measure of the ventilatory threshold, the breathing-based cousin of the lactate threshold. The "equivocal" stage, where you can talk but it is no longer clearly comfortable, matched that threshold, along with a rating of perceived exertion of 10–11 on the 6–20 scale. Zone 2 sits just below it: you can speak in full sentences without gasping.

How do I calculate my zone 2 heart rate?

Estimate your maximum heart rate, then take 60–70% of it. The familiar formula is 220 minus age. A 2001 study in the Journal of the American College of Cardiology by Tanaka, Monahan and Seals pooled 351 studies with 18,712 people and proposed 208 − 0.7 × age instead. It held up in a lab test of 514 healthy adults, was the same for men and women, and the authors note that 220 minus age underestimates maximum heart rate in older adults.

The formulas agree at 40 and differ by a few beats either side. Treat any formula as a starting point; if you know your true maximum from a supervised test, use that.

The Karvonen method, and why it gives a higher number

The Karvonen, or heart-rate-reserve, method adds your resting heart rate to the sum: target = resting HR + a percentage × (max HR − resting HR). Take a 40-year-old with a resting heart rate of 70: the reserve is 180 − 70 = 110, and 60–70% of it gives 136–147 beats a minute, well above the 108–126 from the percentage-of-max method. The percentages mean different things on the two scales, so don't plug watch-zone percentages into Karvonen. When the numbers disagree, let the talk test decide.

Is the fat burning zone real?

Yes, there is an intensity where your body burns the most fat per minute, but it does not decide how much body fat you lose. In a 2002 study in Medicine & Science in Sports & Exercise, Achten, Gleeson and Jeukendrup tested 18 moderately trained cyclists and found peak fat burning (Fatmax) at 64% of maximum oxygen uptake, about 74% of maximum heart rate. Fat burning stayed within 10% of that peak between 55% and 72% of maximum oxygen uptake, and fell to almost nothing above 89%.

Fatmax varies. A 2004 review in Nutrition by Achten and Jeukendrup reports it at 59–64% of maximum oxygen uptake in trained people and 47–52% in a large sample of the general population. The same review says eating carbohydrate in the hours before exercise reduces fat burning significantly compared with exercising fasted. Note that 74% of maximum heart rate sits in zone 3 on a watch, not zone 2, so even the label is loose.

Burning a larger share of fat during a session is not the same as losing fat. Over days and weeks, body fat falls when you use more energy than you eat. Hard intervals burn a smaller share of fat than an easy walk but more total energy per minute, and what decides body fat is the energy balance across the whole week. Work out your daily energy use with the TDEE calculator and set a sensible target with the calorie deficit calculator.

Is zone 2 cardio good for fat loss?

Zone 2 cardio adds a lot of low-strain activity to your week, which helps fat loss when your food is in check, but it is slow for the time it takes. It suits beginners, heavier people and anyone who dislikes hard intervals, because it is easy to recover from and repeat.

What it does well: the 2004 Achten and Jeukendrup review notes that endurance training brings "a multitude of adaptations that result in increased fat oxidation", meaning trained muscles get better at using fat as fuel. That is the aerobic base endurance coaches talk about.

What it does not do: the 2025 Storoschuk review concludes that "current evidence does not support Zone 2 training as the optimal intensity for improving mitochondrial or fatty acid oxidative capacity" in the general population, and that prioritising higher intensities is critical to maximise cardiometabolic benefits, "particularly in the context of lower training volumes". Much of the zone 2 hype, the authors say, comes from elite endurance athletes who train for many hours a week. If you have three hours a week, not fifteen, some harder work earns its place.

The time cost is the other limit. The American College of Sports Medicine's position stand on weight loss (Donnelly and colleagues, 2009) found that 150–250 minutes a week of moderate activity gives "only modest weight loss", that more than 250 minutes a week has been associated with clinically significant weight loss, and that 150–250 minutes improves weight loss when combined with moderate diet restriction. It also says resistance training does not add to weight loss but may increase fat-free mass and fat loss. Our fat burn training guide compares steady cardio, intervals and strength circuits side by side.

How much zone 2 cardio a week for fat loss?

Aim for 150–300 minutes a week of moderate activity, which zone 2 counts as, plus strength training. That is the range the WHO 2020 guidelines on physical activity set for all adults, with 75–150 minutes of vigorous activity, or a mix, as the alternative. The same guidelines recommend regular muscle-strengthening activity for every age group.

Walking counts if it gets your heart rate up and you are slightly out of breath; our walking for weight loss guide covers steps and pace. An indoor or outdoor bike works too, and is kinder to sore knees: see cycling for weight loss.

What does a 6-week zone 2 and strength plan look like?

This plan builds from 75 to about 165 minutes of zone 2 a week, alongside two full-body strength sessions. Use the talk test on every session, and slow down, walk or switch to the bike whenever your heart rate climbs out of your band. Strength sessions are not counted in the cardio minutes.

1. 1

   Week 1: find your pace

   3 × 25 minutes of zone 2 (75 minutes). Calibrate your zone in the first session. Two 30-minute strength sessions: squat to a chair, push-ups against a wall or bench, rows, hip hinges and a plank.

2. 2

   Week 2: add time, not speed

   3 × 30 minutes (90 minutes). Keep the same strength exercises and add a set where form stays clean.

3. 3

   Week 3: a fourth session

   4 × 30 minutes (120 minutes). Put cardio on strength days after lifting, or on separate days, whichever you will actually do. Add a little load to the strength exercises.

4. 4

   Week 4: longer sessions

   4 × 35 minutes (140 minutes). If jogging pushes you out of zone 2, walk briskly on an incline or cycle instead.

5. 5

   Week 5: reach the WHO floor

   4 × 40 minutes (160 minutes), at or above the 150-minute minimum. Strength sessions run 40 minutes now, with heavier rows, split squats and a loaded carry.

6. 6

   Week 6: one harder piece

   3 × 45 minutes plus 1 × 30 minutes (165 minutes). In one session, swap 10 minutes for 5 rounds of 1 minute hard and 1 minute easy, if you have no health limits. Then repeat the cycle with slightly longer sessions, or keep this week as your routine.

Keep the calorie deficit modest: the cardio adds to the energy you use, the strength work holds on to muscle. If the scale has not moved after several steady weeks, read why you are not losing weight in a calorie deficit before adding more minutes.

Why does my heart rate drift up in Indian heat?

In heat, your heart rate rises over a long session even when your pace stays the same. This is called cardiovascular drift. In a 2020 study in Medicine & Science in Sports & Exercise, Wingo, Stone and Ng had 7 active men exercise at 60% of maximum oxygen uptake in 35°C: between 15 and 45 minutes, heart rate rose 19% when running and 17% when cycling, while stroke volume, the blood pumped per beat, fell 20% and 15%.

The authors conclude the drift reflects a real rise in relative intensity. So in a hot, humid Indian summer, slow down and keep your heart rate in the band. By our arithmetic, a heart rate of 125 at minute 15 that rose 19% would reach about 149 by minute 45, well out of zone 2 for most adults.

• Train in the coolest part of the day, usually early morning, or indoors on a treadmill, bike or stair routine with a fan.
• Drink water through the session, and add an oral rehydration solution on long, sweaty days.
• Expect a slower pace in the hottest months, and don't compare it with your winter numbers.
• Stop and cool down at the first signs of heat exhaustion. The NHS says someone with heat exhaustion should start to feel better within 30 minutes of cooling, and that still being unwell after 30 minutes is a sign of heatstroke, an emergency.

Where a coach helps with zone 2 training

Most people do zone 2 on their own. A coach earns their place on the strength side: loads, form and adjusting the plan when the scale stalls. MakeMyFitness is live 1:1 coaching on video across India, ₹799 a session at your own gym or ₹899 at home, and suits someone who already walks or cycles and wants a coach to build the two strength sessions around that cardio and keep the whole week on track for fat loss.

Sessions last 45 minutes and are led by coaches such as Kumar Abhishek. Our coaches are fitness coaches, not doctors, dietitians or physiotherapists. If you have a heart, blood pressure or other medical condition, get your doctor's go-ahead first; our medical disclaimer explains what we do and don't do. If you are coming back from an injury, Rehab & Recovery is exercise coaching after a doctor or physiotherapist has cleared you, not treatment.