HIIT vs LISS: Which is More Effective for Fat Loss?

HIIT

HIIT workouts are typically shorter in duration, ranging from a few minutes to around 30 minutes.

The high-intensity intervals are performed in a structured pattern, with rest periods in between.

LISS

LISS exercises are longer in duration, usually lasting 30 minutes or more.

The emphasis is on maintaining a steady state of exercise for an extended period without the need for structured intervals.

Cardiovascular Fitness

HIIT

HIIT is known for its ability to improve cardiovascular fitness rapidly.

The intense intervals challenge the heart and lungs, promoting cardiovascular endurance and efficiency [2].

LISS

LISS exercises improve cardiovascular fitness by improving aerobic capacity and endurance over longer durations.

While the intensity is lower, LISS still benefits heart health and stamina.

Read More: Low-Intensity Cardio 101 Guide: Benefits and Example Workouts

HIIT

HIIT is highly effective for burning fat and calorie loss. Contrary to popular belief, the duration of LISS cardio does not necessarily equate to burning more calories.

HIIT sessions can actually result in higher calorie expenditure. The intense intervals elevate the metabolic rate, leading to increased calories burned during and after the workout.

LISS

LISS workouts primarily rely on fat as a fuel source, making them effective for burning fat when performed for extended periods.

However, the calories burned during a single session may be lower compared to HIIT.

Muscle Preservation

HIIT

HIIT workouts can help preserve muscle mass while promoting fat loss.

The intense nature of HIIT stimulates muscle engagement and can contribute to overall muscle tone.

LISS

LISS cardio is generally not effective for preserving or building muscle mass compared to HIIT. However, they can be a suitable complement to a comprehensive fitness routine.

HIIT stands for high-intensity interval training. It is a type of exercise regimen that alternates between short bursts of intense exercise and brief recovery periods.

The workouts typically involve performing a specific exercise or a series of exercises at maximum effort for a set time, followed by a short period of rest or low-intensity exercise.

This cycle of high-intensity exercise and recovery is repeated for a predetermined number of rounds or a specific duration.

HIIT helps you build and maintain moderate amounts of lean muscle mass. It also produces an after-burn effect called excess post-exercise oxygen consumption (EPOC).

During HIIT, your body is pushed to its maximum capacity, resulting in a significant increase in oxygen consumption.

After completing a HIIT session, your body continues to consume oxygen at an elevated rate during the post-exercise period to restore various physiological processes to their baseline levels.

This means that even after you've finished your workout, your body continues to work hard to recover, repair muscle tissue, and replenish energy stores, which may result in an extended period of elevated metabolism and calorie burn post-exercise.

The afterburn effect of HIIT can contribute to increased caloric expenditure and potentially promote fat burning.

Research suggests that the intense nature of HIIT workouts stimulates metabolic activity and leads to a greater overall energy expenditure compared to low-intensity exercise [3].

HIIT workouts can be designed for various activities, including running, cycling, bodyweight exercises, or a combination of different circuit training exercises.

"When looking to lose weight, it’s important to focus on what type of weight you lose. Focusing on building or maintaining lean body mass through resistance training (rather than just losing weight) should be a priority.”

- Mary Wing, Certified Personal Trainer

LISS stands for low-intensity steady state and is a form of steady-state cardio.

LISS is an exercise method characterized by maintaining a consistent low-to-moderate level of intensity throughout the duration of the workout.

Unlike HIIT, which involves intense bursts of activity, LISS cardio exercise focuses on sustaining a steady pace for an extended period.

Typically, LISS cardio sessions include walking, light jogging, cycling at a moderate speed, swimming, or using an elliptical machine or quality stair climber at a comfortable pace.

The key principle of LISS cardio is to keep your heart rate elevated within a target range that is lower than your maximum heart rate.

This sustainable intensity allows you to engage in the activity for an extended period, ranging from 30 minutes to several hours.

• Low Impact: Workouts are generally gentle on the joints and muscles, making them suitable for beginners, individuals with injuries, or those who prefer a lower-impact exercise [5].
• Long-Duration Calorie Burn: LISS relies on fat as a fuel source and can provide sustained burning of fat over an extended period, contributing to fat loss.
• Cardiovascular Endurance: LISS exercises improve aerobic capacity and endurance, helping to strengthen the cardiovascular system.
• Active Recovery: LISS can be used as active recovery on rest days or in combination with other high-intensity workouts, promoting muscle recovery and reducing fatigue.

Drawbacks of LISS

• Time Commitment: LISS cardio workouts are typically longer in duration compared to HIIT, which may be a drawback for individuals with busy schedules.
• Lower Calorie Burn per Session: While LISS cardio contributes to fat loss and calorie burning, the calorie expenditure during a single session may be lower compared to HIIT.
• Limited Muscle Stimulation: LISS cardio workouts may not provide significant muscle-building or toning benefits compared to resistance training or HIIT.

“HIIT and LISS workouts offer distinct advantages depending on individual goals and preferences. HIIT, with its high-intensity intervals, stimulates greater calorie burn and can lead to improved aerobic exercise and anaerobic exercise. LISS, characterized by lower-intensity, continuous exercise, is effective for enhancing endurance and can be sustained for longer periods. The choice between HIIT and LISS should consider factors such as fitness level, available time, and individual preferences."

- Dr. Lisa Evans, Sports & Exercise Psychology Expert