The Limits of Cardio for Fat Loss

Ask anyone on the street what is the best way to lose body fat and they will say, "cardio". For decades now, cardio has been hailed as the holy grail of exercise. However, here is what typically happens: someone starts a fat loss program by doing some cardio, they make some initial good progress and then hit a plateau far from their fat loss goal. Why is this?





Note: Before I get into these reasons, I want you to be clear that I didn’t write this to try to bash cardio or to get people to quit doing cardio altogether. Rather it is to explain why cardio alone often fails to get people to their fat loss goal.

Failing to make the necessary nutritional changes

Health & Appropriate Fat Loss Meal

Many people make the mistake of trying to exercise their fat off while failing to realize that nutrition is the number one priority for fat loss.  If your goal is fat loss, be sure to eat appropriately for fat loss. Most people will not be able to out-train poor nutrition. Click HERE for more info on fat loss nutrition.

Choosing the wrong type of cardio
When we first started having an obesity problem, we looked around and saw that good endurance athletes where lean, so we copied them. While that seems to make sense, we often forget that you have to have a naturally long and lean body to be a good endurance athlete. If you have a shorter, stockier build, you will not change your natural body type to long and lean from running. Also, we failed to remember that elite endurance athletes train for hours a day - something most people cannot do with other life commitments. Yes, if you are trying to lose fat you should work on adding more exercise time per week, but you can maximize your training efficiency by doing some high-intensity interval training (if safe and appropriate) for some of that time to take advantage of EPOC. Remember, there are different types of cardio to choose from and you have to pick the right type for you.

Limited progression options
The secret with any form of exercise is to keep progressing the exercise until you reach your goal. Of course that sounds simple, but most people fail to do it in the real world. They run 3 times a week for 20 minutes and complain about how they are not making progress. If you are not at your current fitness/body composition goal, then you need to be progressing your training sessions. Now, if you are doing the above example, you could easily progress by running 25 minutes. However, this limits your progression because you fairly quickly progress to an amount of time that is no longer realistic with your other responsibilities. You could add more days of running per week, but again you are limited because if you run too frequently, you will end up injured. You could run faster, but only so much. Compared to strength (where almost everyone would reach their goals before they hit their genetic limit), improvements in VO2max (how we measure aerobic fitness) are far less substantial and this makes it difficult to rely only on cardio for fat loss.

You become fuel efficient
I often test my students with this question: if your goal is fat loss, do you want to be more or less fuel efficient? The answer: fuel inefficient. Think cars. You want your body to look like and have the fuel efficiency of a sports car – not a Prius. Cardio can work against your fat loss goal by making you more fuel efficient these 3 ways:

Fuel efficiency: great for cars, not for lean bodies

1. You now weigh less: this means moving your body around is easier than it used to and you are burning less calories now than when you first started.
2. You have increased movement efficiency: watch a rookie going for a jog and then go and watch a veteran runner. Even without a biomechanics background, you can easily see that the veteran runner's technique looks smooth and effortless compared to the rookie runner who awkwardly bounces and hobbles along. You see one of the things that makes someone a great runner is that he/she has very economical technique. This is great if you are running to win running races, but if you are trying to burn fat, the better you get at your chosen activity, the less effective that activity becomes for fat loss. Here is a helpful fat loss tip from Dan John: pick activities you are not good at!
3. Improved aerobic fitness: When someone first starts cardio, they are often out of breath. As a result, they work more anaerobically. This means much greater EPOC. However, as they improve their aerobic fitness, they are able to generate a greater percentage of their required energy from aerobic metabolism and this means less EPOC (i.e. less after-exercise calorie burn).

Bottom line: cardio makes you fuel efficient and that is not what you want when you are trying to burn fat.

Hormones
Hormones have a big impact on our bodies. That is why professional bodybuilders inject synthetic hormones into their bodies to not only build huge amounts of muscle, but also to rapidly strip body fat off before a contest. While I'm not here to judge anyone, my hunch is that most people are not going to be injecting hormones into them. However, you can alter your hormones with exercise.
A downside with exercise is that you produce the hormone cortisol. This is a stress hormone that can lead to muscle wasting (losing muscle = slower metabolism) and has been linked to abdominal obesity. High levels of aerobic training can lead to high levels of corstisol. While cortisol is produced with resistance training, it is not as significant because the resistance training is a shorter activity (even an hour’s strength training session is not one straight hour of resistance training because of all the rest time). Also, what is really important is the ratio of anabolic hormones (ones that build the body up) to catabolic (ones that break the body down). One of the reasons weight training is so effective for fat loss is that it increases natural secretions of hormones that build lean muscles (thus raising your metabolism) and burn fat (e.g. testosterone, human growth hormone and insulin-like growth-factor1).

Personal experience
As a trainer I have spent countless hours in gyms of the years. I have seen many people who religiously do cardio day in and day out, month after month and yet fail to reach their fat loss goals. I cannot ignore this evidence.

In Conclusion:
Again, I’m not trying to bash cardio. I simply want to explain why I believe anyone trying to drop body fat will limit their results if they only choose cardio. I hate to see people putting in huge amounts of time and efforts and not getting results they deserve.

To lose fat, be sure to prioritize correctly. Check out this post for the Priorities of Fat Loss. Also, for more information on weight training for fat loss, check out this post on Why Weight Training is So Effective for Fat Loss.

Also, for fitness professionals and those who want to have an excellent understanding of the science and application of fat loss, check out my upcoming fat loss workshop HERE.