Is It Better to Start with Cardio or Weights? New Research Reveals Optimal Workout Order for Fat Loss

Decoding the Best Exercise Sequence: Cardio or Weights First?

For decades, fitness experts and enthusiasts worldwide have debated whether beginning a workout session with cardiovascular exercise or strength training delivers the best results for fat loss, fitness, and health. Traditionally, the choice often boiled down to individual goals and personal preference. However, emerging scientific insights are changing that landscape, highlighting how the order of cardio and resistance training can significantly shape workout outcomes, especially for fat loss and metabolic health.

Groundbreaking Study Sheds Light on Workout Order

A recent controlled study led by exercise scientists has provided new answers to this enduring fitness question. The research enrolled 45 obese young adult men, aged 18 to 30, dividing them into three distinct groups over a 12-week period. One group maintained their regular daily routines with no exercise intervention, serving as a control. The other two groups undertook identical training programs, working out three times per week for 60 minutes per session—but with a crucial difference: the order of exercises.

Participants in both active groups completed daily strength and cardio components. The resistance workouts featured classic weightlifting exercises such as bench presses, deadlifts, bicep curls, and squats, targeting major muscle groups. The cardio component consisted of 30 minutes on a stationary bike. To ensure data accuracy, each participant wore a sports activity tracker, giving researchers objective insights into daily movements and total physical activity—an improvement over self-reported metrics, which can be unreliable.

Remarkable Results: Weights First for Greater Fat Loss

Over the 12-week program, both exercise groups saw improvements in aerobic fitness, muscle strength, and body composition—losing fat mass and increasing lean muscle. However, participants who began with resistance training followed by cardio demonstrated noticeably superior outcomes. They achieved greater reductions in total and visceral fat—the abdominal fat associated with higher risks of cardiovascular disease and metabolic disorders. Notably, the weights-first group also increased their daily step count by approximately 3,500 steps, compared to 1,600 for those starting with cardio. Moreover, this sequence enhanced muscular endurance and explosive strength, underlining its advantage for those seeking both fat loss and functional fitness improvements.

The Science: Why Does Exercise Order Matter?

Understanding why starting with resistance training optimizes fat burning involves delving into the body’s metabolic pathways. During strength training, the body taps into muscle glycogen—stored carbohydrates—as an immediate source of energy. Exhausting these stores prepares the body to rely more on fat reserves during subsequent cardio, since glycogen—akin to fuel in a tank—has already been depleted. This biochemical shift mirrors a hybrid vehicle switching to electric power once its fuel is low. As a result, post-lifting cardio drives the body to burn more fat for energy.

This mechanism aligns with broader exercise science research. A comprehensive systematic review in 2022 found that resistance training alone significantly reduces both overall and visceral fat, even without accompanying cardio. Muscles are metabolically active, burning energy even at rest, and thus contribute to continuous fat oxidation.

Cardio First: Potential Downsides for Strength and Fat Loss

Conversely, prioritizing cardio can partially deplete glycogen stores and induce early fatigue before weight training begins. This order may limit one's capacity to generate maximal force and develop explosive strength. Research on concurrent training—combining resistance and aerobic exercise within the same session—suggests that performing cardio first may blunt gains in explosive strength and power.

Meta-analyses and recent systematic reviews consistently show superior strength increases when lifters start with resistance work. The American Heart Association’s 2023 guidelines also affirm that strength training, particularly when paired with other exercise modalities, efficiently increases lean body mass and reduces body fat—critical factors in combating obesity and chronic diseases.

However, for enhancing cardiovascular health markers, such as heart and lung function, the sequence is less critical; both orders deliver similar improvements in aerobic fitness.

Limitations and Future Questions

While these findings are compelling, they are not without limitations. The study focused exclusively on young men with obesity, so results may differ for women, older adults, or those with varied body compositions. In fact, a 2024 review indicates that sex-related physiological differences can reshape how the body responds to different exercise sequences, highlighting the need for future research across diverse populations.

Additionally, the experiment spanned three months—insufficient to capture potential long-term adaptations. It also tracked exercise performed within a single session (concurrent training), leaving open questions about separate sessions on different days. Finally, important lifestyle factors such as nutrition, sleep quality, and psychological stress—all influential in body composition—were not controlled during the trial.

Key Takeaways for Fitness Programming

The overarching message for the general public and those designing science-based exercise routines is clear: incorporating both resistance and aerobic exercises is crucial for holistic health, supporting improvements in both cardiovascular fitness and metabolic function. However, for individuals prioritizing fat loss, reductions in abdominal (visceral) fat, and greater daily activity, placing weight training before cardio seems to deliver the greatest benefits.

Another notable advantage is the psychological empowerment gained from resistance sessions, which often boost confidence and motivation—surprisingly leading individuals to move more and become more engaged in physical activity throughout the day, further supporting energy expenditure and weight management.

That said, if your primary aim is to boost heart and lung capacity (cardiorespiratory fitness), the sequence of exercises is less critical. Both approaches provide similar gains in endurance capacity, making room for tailoring programs to personal enjoyment and adherence.

Conclusion

Current scientific evidence reinforces that both cardio and strength training are central pillars of a healthy lifestyle. Yet, if maximum fat loss and an increase in daily movement are your chief goals, beginning with resistance training before transitioning to cardio offers distinct advantages. As research progresses and explores more diverse populations, our understanding of how to optimize exercise order will continue to evolve, providing even more personalized and effective fitness guidance. Always consider your individual goals, consult with scientifically informed trainers or health professionals, and enjoy the substantial health rewards of a balanced, thoughtfully sequenced exercise program.