By FoodVersus Editorial Team | Dubai, United Arab Emirates
If your goal is to lose fat, should you spend your gym time lifting weights or doing cardio? Walk into any gym and you will hear confident answers on both sides: cardio "burns the fat," while weights "build the muscle that burns fat all day." Both statements contain some truth, which is why the debate never ends.
Randomized trials that compare the two directly give a clearer picture than the gym folklore. This article walks through what they found, what the official physical activity guidelines recommend, and how to combine the two without spending your whole week exercising.
The Short Answer
For reducing fat mass and body weight, aerobic exercise (cardio) performed alone has been shown to do at least as well as, and in some trials better than, resistance training alone. For building or protecting muscle, resistance training is clearly the stronger tool. Combining the two gives the benefits of both, and when you are eating less to lose weight, adding resistance training matters most for keeping lean tissue. Exercise also supports weight loss alongside, not instead of, changes in eating, which our comparison of exercise and diet explores in more depth.
What Each Type of Exercise Does Best
| Factor | Cardio (Aerobic) | Strength Training (Resistance) |
|---|---|---|
| Examples | Brisk walking, jogging, cycling, swimming, rowing | Weights, machines, resistance bands, bodyweight exercises such as push-ups |
| Effect on fat mass and body weight | Larger reductions than resistance alone in the trial below | Smaller reductions than cardio in the trial below |
| Effect on lean (muscle) mass | Little or no gain | Increases lean mass |
| Best known for | Calories burned during the session, cardiovascular fitness | Strength, muscle preservation, function and mobility |
The Key Trial: Cardio, Weights, or Both for 8 Months
One of the most informative comparisons is the STRRIDE AT/RT trial (Willis et al., Journal of Applied Physiology, 2012). It randomized sedentary adults with overweight or obesity to one of three supervised programs for eight months: resistance training alone, aerobic training alone, or both combined. In the published abstract, the researchers reported that:
First, the aerobic-only and the combined programs produced greater reductions in fat mass and total body mass than resistance training alone, and these two programs did not differ from each other on those measures. Second, resistance training and the combined program increased lean body mass more than aerobic training alone. Third, the combined program required about double the time commitment of either single approach.
In plain terms, cardio was the more efficient tool for losing fat and weight, resistance training was the tool for gaining muscle, and doing both delivered both benefits but at a cost in time. For a person who wants the least time for a given result, the findings suggest that cardio does the heavy lifting for fat loss, while strength work protects the body composition you end up with.
Why Weights Matter More When You Are Dieting
When people lose weight by eating less, some of what they lose is muscle rather than fat. A trial in older adults with obesity (Villareal et al., New England Journal of Medicine, 2017) examined how exercise type changes that. Participants who followed a weight-management program were assigned to aerobic exercise, resistance exercise, or both, and were compared with a control group over six months. Body weight fell by about 9% in all of the exercise groups, but the effect on lean mass differed:
| Group (weight management plus) | Lean Mass Change | Physical Performance Test Improvement |
|---|---|---|
| Aerobic only | -5% (55.0 to 52.3 kg) | +14% |
| Resistance only | -2% (58.1 to 57.1 kg) | +14% |
| Combined | -3% (56.5 to 54.8 kg) | +21% |
Two takeaways stand out. Everyone who dieted lost some lean mass, but the group that did only cardio lost the most, while those who included resistance training lost less. And the combined group showed the biggest improvement in physical function. Because this trial studied older adults with obesity, the numbers should not be applied directly to younger people, but the broader principle, that resistance training helps protect muscle during weight loss, is widely accepted and is why it features in guidance for people using appetite-suppressing medications as well.
What the Official Guidelines Recommend
The Physical Activity Guidelines for Americans (2nd edition) recommend that adults get at least 150 to 300 minutes of moderate-intensity aerobic activity per week, such as brisk walking, plus muscle-strengthening activity on at least 2 days per week, such as lifting weights or doing push-ups. The guidelines frame both as part of overall health and note that physical activity helps people maintain a healthy weight and lowers the risk of excessive weight gain. In other words, the official advice is not "cardio or weights," but both.
A Simple Weekly Plan That Uses Both
You do not need to double your exercise time to benefit from both types. A realistic starting structure for a healthy adult might look like this:
| Component | Example | Weekly Total |
|---|---|---|
| Cardio | Brisk walking or cycling, 30 minutes on 5 days | 150 minutes |
| Strength training | Full-body session (squats, presses, rows, carries), 30-40 minutes on 2 days | 2 sessions |
Beginners can start with less and build gradually. Consistency over months matters more than any single workout, and the best plan is the one you can actually repeat. Pairing this with adequate protein, as covered in our guide to daily protein targets, supports muscle preservation while you lose fat.
What About HIIT?
High-intensity interval training (short bursts of hard effort alternating with recovery) is popular because it compresses cardio into less time. It can be an effective form of cardio for people who are fit enough for it, but it is also demanding on joints and recovery, and the trials discussed above did not test it. For most beginners, steady moderate cardio plus basic strength training is a safer and more sustainable starting point than jumping straight into high-intensity work.
Who Should Be Careful
Starting a new exercise program carries more risk for some people than others. Anyone with heart disease, high blood pressure, diabetes, joint or back problems, osteoporosis, a history of injury, or who has been inactive for a long time should speak with a doctor before beginning, particularly before vigorous exercise or heavy lifting. People who are pregnant, recovering from surgery, or taking medications that affect heart rate or blood sugar also need individual guidance. Learning proper lifting technique, ideally from a qualified trainer, reduces the chance of injury. Stop exercising and seek medical help if you experience chest pain, severe shortness of breath, dizziness, or fainting.
A Note on Using This Information
This article summarizes findings from published clinical research and public health guidelines for general educational purposes and does not constitute medical advice, exercise prescription, or a substitute for professional evaluation. The studies cited involved specific populations and programs, including one in older adults with obesity, and their group averages do not predict any individual's results. Fat loss, muscle change, and injury risk depend on age, health status, diet, sleep, medications, genetics, and exercise technique, which a general article cannot assess.
Consult a doctor before beginning or significantly changing an exercise program, especially if you have a chronic health condition, take regular medications, are pregnant, or have not exercised in a long time. A certified fitness professional or physical therapist can help tailor a program to your abilities and goals.
Primary sources referenced in this article:
1. Willis LH, Slentz CA, Bateman LA, et al. "Effects of aerobic and/or resistance training on body mass and fat mass in overweight or obese adults." Journal of Applied Physiology, 2012;113(12):1831-1837: https://doi.org/10.1152/japplphysiol.01370.2011
2. Villareal DT, Aguirre L, Gurney AB, et al. "Aerobic or Resistance Exercise, or Both, in Dieting Obese Older Adults." New England Journal of Medicine, 2017;376(20):1943-1955: https://doi.org/10.1056/NEJMoa1616338
3. U.S. Department of Health and Human Services, Physical Activity Guidelines for Americans, 2nd Edition (Top 10 Things to Know): https://odphp.health.gov/our-work/nutrition-physical-activity/physical-activity-guidelines/current-guidelines/top-10-things-know
About the Author
This article was written by the FoodVersus Editorial Team, based in Dubai, United Arab Emirates. FoodVersus publishes research-based comparisons and guides on nutrition, diet, and weight loss, with every article citing its primary sources. Our content is for general education and is not a substitute for professional medical advice.
Strength Training vs Cardio, Cardio vs Weights for Fat Loss, Best Exercise for Fat Loss, Resistance Training Fat Loss, Aerobic Exercise Weight Loss, Cardio and Strength Training Combined, Muscle Loss While Dieting, Preserve Muscle Weight Loss, Physical Activity Guidelines, Weekly Workout Plan, Exercise for Weight Loss
Comments
Post a Comment