How many times per week should I do HIIT?

2-3 times per week is the evidence-based maximum for most people. HIIT is taxing on the nervous system, joints, and muscles. More than 3 sessions/week leads to overtraining without proportional benefit. Always take at least 1 full rest day between HIIT sessions.

HIIT vs LISS Cardio: Which Burns More Fat?

HIIT: High-Intensity Interval Training

HIIT alternates short bursts of intense effort (80-95% max heart rate) with recovery periods. A typical HIIT session: 20 seconds sprint, 40 seconds walk, repeated 8-10 times (20-30 minutes total).

Pros: Time-efficient (20-30 min = equivalent calorie burn to 45-60 min LISS), elevated post-exercise oxygen consumption (EPOC/"afterburn" burns 6-15% more calories for 12-24 hours), preserves more muscle than steady-state cardio, and improves VO2 max rapidly.

Cons: High injury risk (esp. knees, ankles), requires full recovery (2-3 days between sessions), not suitable for beginners, and requires significant motivation/intensity.

LISS: Low-Intensity Steady-State Cardio

LISS is sustained aerobic activity at 50-65% max heart rate for 30-60+ minutes — brisk walking, easy cycling, elliptical, light jogging. Zone 2 training is a subset of LISS.

Pros: Low injury risk, can be done daily, recovery-friendly (enhances recovery from strength training), builds aerobic base, and is psychologically sustainable long-term.

Cons: Time-consuming relative to calorie burn, can blunt strength gains if excessive, and requires more total time investment.

Which Burns More Fat?

Calorie comparison (150-lb person): 30 min HIIT burns ~300-450 kcal. 45 min brisk walk burns ~200-280 kcal. HIIT wins on calories-per-minute. However, LISS allows more total daily activity without recovery cost — walking an extra 10,000 steps/day (NEAT) can burn 300-500 extra calories with zero recovery cost.

The truth: Both work. Total calorie deficit determines fat loss, not which cardio mode. The best cardio is the kind you'll do consistently, that doesn't compromise your strength training, and that fits your schedule.

Optimal Strategy

For most people: 1-2 HIIT sessions per week (not on heavy strength training days) + 3-5 LISS sessions (brisk walking, cycling) + maximize NEAT (walk more, take stairs). This approach gives HIIT's metabolic benefits without excessive recovery demands, while LISS supports fat loss without injury risk.