“Zone 2 cardio is the best exercise for fat loss.”
Zone 2 cardio helps with fat loss, but it has not been shown to beat other types of exercise for it.
Steady, easy-paced cardio is a good way to lose fat if you enjoy it, but there is nothing special about Zone 2 for fat loss. Harder intervals work about as well in less time, so pick the pace you will keep doing week after week. For how cardio compares with lifting, see our card "Cardio is the best exercise for fat loss."
Choose the cardio you will do most weeks, at whatever pace suits you, and add muscle-strengthening activity at least 2 days a week.
Safety note: Very intense exercise raises short-term cardiovascular and injury demands. Increase intensity gradually and include recovery, especially if you are new to exercise.
Talk to a healthcare professional if: you have chest pain, fainting or unexplained breathlessness with exercise, or you have a heart or lung condition and plan to start harder training.
Trials comparing steady moderate cardio with interval training find similar fat loss, with at most a small edge for intervals, so steady cardio works but is not the best. Confidence is moderate because the trials are short and most of the reviews pooling them were rated low quality.
Zone 2 cardio helps with fat loss, but it has not been shown to beat other types of exercise for it. In trials, steady moderate cardio, the closest match to Zone 2, took off about as much body fat as harder interval training, and one large review gave intervals a small edge of under 1 percentage point of body fat. In the trials, both kinds of cardio took off modest amounts of fat over about 10 weeks, and intervals did it in about 40 percent less time.
Zone 2 means steady, low-intensity exercise below the lactate threshold, the point where lactic acid starts to build up in the blood. A 2025 review found the evidence does not support Zone 2 as the best intensity for building the body's capacity to burn fat, and found that harder exercise matters for heart and metabolic health, especially when training time is limited. In a review of 13 trials, the programs changed body fat more than body weight.
US physical activity guidelines advise adults to get at least 150 to 300 minutes a week of moderate aerobic activity, such as brisk walking, plus muscle-strengthening activity at least 2 days a week. They do not single out any one training zone.
- Kramer AM, Martins JB, de Oliveira PC, Lehnen AM, Waclawovsky G. High-intensity interval training is not superior to continuous aerobic training in reducing body fat: A systematic review and meta-analysis of randomized clinical trials. Journal of Exercise Science and Fitness. 2023;21(4):385-394. DOI: 10.1016/j.jesf.2023.09.002. PMID: 37927356. PMCID: PMC10624584
- Poon ET, Li HY, Little JP, Wong SH, Ho RS. Efficacy of Interval Training in Improving Body Composition and Adiposity in Apparently Healthy Adults: An Umbrella Review with Meta-Analysis. Sports Medicine. 2024;54(11):2817-2840. DOI: 10.1007/s40279-024-02070-9. PMID: 39003682. PMCID: PMC11560999
- Wewege M, van den Berg R, Ward RE, Keech A. The effects of high-intensity interval training vs. moderate-intensity continuous training on body composition in overweight and obese adults: a systematic review and meta-analysis. Obesity Reviews. 2017;18(6):635-646. DOI: 10.1111/obr.12532. PMID: 28401638
- Storoschuk KL, Moran-MacDonald A, Gibala MJ, Gurd BJ. Much Ado About Zone 2: A Narrative Review Assessing the Efficacy of Zone 2 Training for Improving Mitochondrial Capacity and Cardiorespiratory Fitness in the General Population. Sports Medicine. 2025;55(7):1611-1624. DOI: 10.1007/s40279-025-02261-y. PMID: 40560504
- US Department of Health and Human Services, Office of Disease Prevention and Health Promotion. Top 10 Things to Know About the Second Edition of the Physical Activity Guidelines for Americans