This is a question that has been asked every since Jane Fonda put on a leotard and started the aerobics craze. There is a lot of information out, most of it from someone trying to sell you a panacea, a one size fits all cure, it doesn’t exist. I’ve outlined the 5 reasons, based on science and research, to help you put together a sensible approach to the strength trainer or cardio for weight loss questions. They address the three biggest mistakes I’ve seen people make when trying to lose weight, too much cardio, not lifting heavy enough weights and trying to exercise more without changing their approach to nutrition.

People have gotten the best results when they combine appropriate intensity strength training with a sensible level of cardio. Below are the reason science says it works.


  1. When you do cardio your body will burn fat/calories for energy. Your muscles are the where it is burned. The more muscle you have the more fat and calories you burn when you do your cardio. Your muscle is home to the mitochondria. Mitochondria are the furnaces of your body literally as they are responsible for your body heat. Without mitochondria you would produce no body heat. This is where the majority of those fat and calories are burned. The more mitochondria you have the greater your capacity for burning fat and calories. Strength training builds muscle and increases mitochondrial density in existing muscle, which results in more calories burned during cardio sessions.
  2. Burning more fat and calories 24/7. We ‘ve talked about the After burn effect where your burn more calories for a window of time after an intense workout, with added muscle you get an increase in your metabolic rate 24 hours a day 7 days a week. Muscle burns calories even when you are sleeping. One of the most effective ways to boost your metabolism is to add muscle to your body.
  3. Muscle is what gives your body its shape. We’ve all heard the term “skinny fat” where people are thin but are still lack muscle tone. There is nothing worse than busting your butt in a workout and still not looking like you workout. If you want to have a great butt, sculpted shoulders and arms and a 6 pack then you have to have muscle. Strength training is the only way to get that muscle. You have to lift weights that are heavy enough to cross the adaptation threshold of your muscles. It has to challenge your muscles are you are wasting your time. Your body is not a machine, it is an adaptive organism. It will adapt to whatever to throw at it, but you have to challenge it if you want it to change. Don’t waste your time with weights that are too light to cause any change in your body. Don’t worry ladies you won’t bulk up for one simple reason, Hormones, you simply don’t have enough testosterone to build the amount of muscle that men can. This myth has been debunked by several studies.
  4. Do Cardio. I’m not saying to abandon cardio for weights, just don’t forsake strength training for cardio only. Strength training “Enhances” your cardio for all the reasons previously stated. It is important to do cardio for many reasons, health, mental well-being among them, just be sure to add in strength training to get the most out of it and optimize your health.
  5. Proper nutrition is the best way to lose weight. Several studies have shown that you can’t out exercise poor nutrition. The most effective way to lose weight is by eating healthy. The most effective way to improve your fitness is to exercise. They work hand in hand and combining the two will give you a synergistic effect, think 2+2=5, but don’t be confused. If you want to lose weight you will have to address your nutrition no matter how much you exercise.

Now you know that you should do both if you want to achieve healthy, long-term weight loss, but which one should you do first? The answer, as always, is it depends. You should start with whichever activity is most important to you. Until recently, scientists thought it was simply a matter of logistics: if you’re tired from the treadmill, you cant lift as much weight, so over time you put on less muscle. But new techniques now allow researchers to directly measure which specific proteins are produced in muscles after different types of exercises. It turns out that the sequence of cellular events that leads to bigger muscles is determined in part by the same “master switch”- an enzyme called AMP Kinase- that controls adaptations for better endurance. But you can’t have it both ways: the switch is set either to “bigger muscles” or to “better endurance” and the body can’t instantly change from one setting to the other. How you start your workout determines which way the switch is set for the session. Think heating and air conditioning. You wouldn’t try to control the temperature in your home by using both simultaneously. You would use one or the other, but not both. The same should go for your training sessions. Set a goal for each training session, build muscle or burn fat and go for it.