When it comes to losing weight, most people instinctively turn to cardio. Whether it’s running, cycling, or hopping on an elliptical, cardio feels like the go-to option for shedding pounds. And it works—to a degree. Cardio does burn calories and helps reduce fat mass. But if the goal is not just to lose weight but also to improve body composition by reducing fat while maintaining or building muscle mass, cardio alone may not be the most effective approach.
Let’s break this down using both practical experience and scientific evidence.
Weight loss includes reductions in skeletal muscle mass (including bone), water weight, and fat mass. But losing muscle or water isn’t healthy. For every overweight person, the primary aim should be to lower body fat percentage, not total body weight.
That’s why I don’t recommend relying solely on the scale. After a tough cardio session, body weight may drop due to sweating and water loss. But after rehydrating, that weight typically returns. More sweat doesn’t mean more fat loss.
Instead of chasing lower numbers on the scale, focus on changes in body fat percentage, which can be measured monthly.
Aerobic training is effective at reducing fat mass. It creates a significant calorie deficit, especially in longer or higher-intensity sessions.
A 2010 study by Stephen H. Boutcher highlighted that high-intensity interval exercise (HIIE) was effective in reducing subcutaneous and abdominal fat, particularly in overweight and diabetic individuals. HIIE also increased insulin sensitivity by 25% within 24 hours post-exercise, although this effect diminished after 72 hours. Results varied—from 8 kg fat loss in some responders to no change in non-responders.
For example, Wingate-style sprints (30 seconds all-out) were highly effective, but newer protocols like 8-second sprints with 12-second rests are being developed to increase accessibility
A similar study conducted by scientists at Duke University on 196 obese or overweight men and women ranging from 18 to 70 years old, split them into three groups:
· Group one did three one-hour resistance training workouts per week
· Group two jogged three days per week at a moderate intensity for about 45 minutes per session
· Group three did both the resistance training and cardio workouts.
Which group lost the most weight? Group 2, the cardio-only group, was the only group that lost muscle as well. On the contrary, group 3 (the resistance plus cardio group) lost the fattest while also gaining muscle.
A randomized controlled trial in overweight, sedentary males found that compared the effects of two exercise programs, 30 minutes (MOD) and 60 minutes (HIGH) of daily aerobic exercise, on body fat loss and energy balance in sedentary, moderately overweight men. Both programs led to significant fat loss, reducing body fat by 14%, with the weight loss coming entirely from fat mass. Interestingly, the shorter 30-minute exercise program (MOD) resulted in a greater than expected negative energy balance—a “bonus effect”—while the more extended 60-minute program (HIGH) showed a small degree of compensation, reducing its effectiveness.
The compensation observed in HIGH appeared to stem from a slight increase in energy intake and possibly other factors like decreased non-exercise activity (NEAT). In contrast, MOD may have encouraged increased NEAT, helping participants burn more calories throughout the day beyond the exercise. This suggests that moderate doses of exercise may optimize energy balance and fat loss without triggering compensatory behaviours like overeating.
The meta-analysis by James E Clark examined the effectiveness of various treatment approaches for addressing excess body fat and improving health outcomes in overfat adults. The study found that combining resistance training (RT) with dietary changes was significantly more effective than either diet alone or diet combined with endurance training (ET). This combination reduced body and fat mass and preserved fat-free mass (FFM) while improving hormonal profiles and lipid markers, such as cholesterol and triglycerides.
Dietary interventions, while effective, were less impactful compared to exercise-based protocols. However, hypocaloric diets with a higher proportion of protein were beneficial for approximately 55% of participants, particularly when exercise was not incorporated. The analysis emphasized that effective fat loss and health improvements are driven by more than just acute energy deficits. Chronic hormonal and metabolic adaptations play a key role, underscoring the complexity of factors that influence health outcomes for overweight individuals.
Resistance training may not always yield the highest raw fat loss, but its benefits are essential:
A 2025 meta-analysis by Kworewinski Lafontant et al. analyzed 114 comparisons across 81 studies and 3,500+ participants:
Aerobic training alone led to greater fat mass loss (approx. 1.06 kg more) than resistance training.
Concurrent training (cardio + resistance) showed fat loss comparable to cardio alone.
Resistance training was best for preserving fat-free mass (FFM), an important factor for health and metabolism.
The analysis also emphasized that when total workload or energy expenditure is matched, fat loss between resistance and aerobic training is similar. However, matching cardio’s energy output using weights alone is often impractical unless advanced techniques (like supersets or cluster sets) are used.
Beyond calorie burn, resistance training changes the body at a molecular level:
Improves fuel utilization and fat oxidation capacity
Enhances metabolic flexibility, especially when training under low-glycogen states
Stimulates the release of myokines and extracellular vesicles that tell fat tissue to release and oxidize fat
Increases production of growth hormone, testosterone, and other favourable fat-burning hormones
These benefits support sustainable fat loss, even if short-term scale changes are modest.
While aerobic training is effective for raw fat mass loss and resistance training excels at muscle preservation, concurrent training combines the best of both. It allows individuals to:
Reduce fat mass
Preserve or build lean muscle
Improve resting energy expenditure
Enhance insulin sensitivity and nutrient partitioning
Support cardiovascular and metabolic health
This strategy is especially effective for individuals aiming to recomp—reduce body fat while building muscle
The study titled “Fat Loss Depends on Energy Deficit Only, Independently of the Method for Weight Loss” suggests that the key to fat loss is not the specific weight-loss method but instead creating an energy deficit. The research emphasizes that whether weight loss is achieved through diet, exercise, or a combination of both, the primary determinant is the balance between energy intake (calories consumed) and energy expenditure (calories burned).
The study highlights that while different strategies may have varying effects on muscle retention, metabolic adaptations, and health markers, fat loss ultimately occurs when there is a sustained negative energy balance. Therefore, the most important factor for fat loss is reducing caloric intake or increasing physical activity, whichever method helps create that deficit.
Fat loss is ultimately driven by energy deficit. However, how you achieve that deficit matters.
If the goal is just fat loss, cardio can be effective. But if your goal is to lose fat, retain or build muscle, and improve body composition, concurrent training is the most evidence-based approach.
Here’s the recommended structure:
3–4 resistance training sessions per week
2–3 moderate-intensity cardio sessions
Adequate protein intake to support muscle repair
Sufficient sleep and stress management to optimize hormonal response
Track body fat percentage, not just weight
The smartest fat-loss strategy doesn’t rely solely on cardio or weights, but intelligently combines both while maintaining a consistent energy deficit.
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Rosenkilde, M., Auerbach, P., Reichkendler, M. H., Ploug, T., Stallknecht, B. M., & Sjödin, A. (2012). Body fat loss and compensatory mechanisms in response to different doses of aerobic exercise—A randomized controlled trial in overweight sedentary males. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. https://doi.org/R-00141-2012
Strasser, B., Spreitzer, A., & Haber, P. (2007). Fat loss depends on energy deficit only, independently of the method for weight loss. Annals of Nutrition and Metabolism, 51(5), 428-432. https://doi.org/10.1159/000111162
Kworewinski Lafontant et al. (2025). Meta-analysis of RT vs. AT vs. CT for fat loss
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