A combination of cardio and weight-training is most effective for weight loss.
Since burning calories helps you lose weight, cardio seems the obvious choice for weight-loss exercise. After all, it's not up for dispute that cardio burns more calories than weight training during a session. But the answer as to whether weights or cardio is better for weight loss isn't so simple as the number of calories burned in one workout. To achieve a slim physique, you need to build muscle mass, which helps your body look toned and burn calories all day long. Your best option is to make time for both activities in your weekly schedule.
Go for a run and sweat; you almost feel the calories pouring out of you. A study published in the "Journal of Applied Physiology" in 2012 comparing the weight-loss effects of cardio and weight-training affirmed cardio's virtues. The participants who stuck to cardiovascular exercise lost more weight than their strength-training only counterparts. In the short term, the Duke University researchers concluded that cardio exercise is optimal for shedding extra weight.
The Cardio Conundrum
Over time, though, you'll hit a plateau with continuous steady-state cardio activity. Certified Strength and Conditioning Coach, Rachel Cosgrove, notes in her book "The Female Body Breakthrough" that doing just cardio with no strength training creates an environment that eventually inhibits fat loss. In response to the constant stress of aerobic exercise, the body becomes more efficient at storing fat. If you are dieting along with the cardio exercise, your body may begin to eat away at your muscle for fuel. Couple this with the natural loss of muscle mass that occurs with age, and you end up with less muscle despite your daily slog on the treadmill. Muscle is more metabolically active than fat, so it helps you burn calories all day long. Cardio may help you burn calories during your 30- or 60-minute session, but it zaps your body's ability to burn calories later.
A weight-training program performed regularly for 10 weeks can boost your metabolic rate by 7 percent, notes a paper in a 2012 issue of "Current Sports Medicine Reports." You may not experience the immediate weight-loss effects of this boost but, over time, weights help you keep the pounds off. Weight training also improves your body composition by increasing muscle mass. With less fat and more lean muscle -- which takes up less space than bulky fat -- you'll look fitter and more toned. Weight training also strengthens your bones and keeps you functioning optimally well into old age.
Prioritize for Perfection
If you've got a substantial amount of weight to lose and limited time to exercise, you're probably better off prioritizing cardiovascular exercise, says Leslie Willis, an exercise physiologist and lead author on the Duke University study. You just can't beat the short-term calorie burn effects. After you've lost some weight, add in strength training to preserve lean muscle and create a fitter appearance. Just two, weekly 20-minute, total-body strength training sessions using heavy weights can be enough to reap benefits. If you're short on time, consider combining cardio and strength training in a circuit-style format in which you do a minute or two of cardio between each set of weights. You'll keep your heart rate high, burn calories and build muscle.