Is Cardio Effective for Fat Loss?

We hear it all the time: If you want to lose weight then start running, swimming, jogging, biking, etc.  However, we then see many people who have been jogging for over a year or more and really don’t look much different than they did before.  Although, then there are those few who come out looking radically different than they did a year ago (whether they keep the weight off or not is a different story).

So what’s the story? Is cardio really effective for fat loss?

The short answer: It depends.

The long answer:

In order to lose weight, you must burn, through metabolism and movement, more calories than you consumed at the end of each day.  There is no escaping this rule; it is a fundamental law of thermodynamics: energy cannot be created or destroyed, only transferred. Any weight loss system that tells you otherwise and still works is somehow “tricking” you into eating less calories or exercising more.

Now that we got that out of the way, it should be obvious what cardio depends on in order to be effective: diet.

For the most part, cardio just acts as a way to increase the calories burned that day. So, if your metabolism burns 2500 calories everyday and then you run for a half-hour one day burning 500 calories, then your total calorie burn for that day was 3000 calories.  It’s really as simple as that.

If the real-world actually acted like the above example, then cardio would always be effective for fat loss. The problem is that many people don’t keep their diet the same when they are doing cardio.

Many people see cardio as a way to “justify” eating more that day because they burned off a lot of calories running, and so they “deserve” that large cookie.  The problem with this is that people almost always vastly overestimate the amount of calories they burned while doing cardio and significantly underestimate how many calories are in whatever they are eating.  Furthermore, cardio increases hunger for most people, much of the time disproportionately to the amount of calories that were burned from the cardio.

However, if, for example, you burned 500 cals doing cardio and then ate exactly 500 cals more that day, you would come out with a calorie balance, but the cardio could still have some calorie partitioning effects.  This means that more of the calories that you ate would go toward muscle-building stuff and more of the calories that you burned would go towards fat-loss stuff.  This minor change in body composition is slight, though. So don’t expect to see any radical changes from using only this method.
Also, just so you know, weight lifting has a much, much larger calorie partitioning effect.

Another good side effect of cardio is that it can help with “stubborn fat”, especially in girls. Stubborn fat is hips and thighs for girls and abs and lower back for guys, for the most part.  This is always the last fat to come off, but the process can be sped up using some specific types of cardio, but that is for a later article.
(Note: I did not say you can spot reduce fat, ’cause you can’t.)

If you want to know if cardio will help you personally in your quest to lose some fat, you have to ask yourself this question: Will doing cardio help or hinder you sticking to your diet?

For some people, doing cardio will fuel their motivation and make them feel like “Well I don’t want to go through all that running and then get nothing out of it”. For others, they use cardio to justify having an all-you-can-eat day. It really just depends on the person.  Also, if cardio really spikes your hunger, then you might want to try either a different form of cardio (HIIT => steady-state || steady-state => HIIT) as some people have different reactions to different intensity levels, or you can just not do it at all and put all your focus on weight training instead.

Lastly, from a physiological standpoint, to decide if the calorie partitioning effect of cardio is necessary for you, you need to look at your starting body-fat percentage. If you have a lot of body-fat, then you won’t really see much improvement from cardio because most of the calories from the calorie deficit due to the diet will come from fat anyway, so jogging 500 cals off will have about the same effect as not eating that muffin, and not eating the muffin takes a lot less time.

If you are starting out with a fairly low body-fat level, then you may see some improvement from incorporating some cardio to increase the calorie deficit. Just make sure that if you add a TON of cardio that you are not going into too much of a calorie deficit, because then your body will be more inclined to take the energy it needs from your lean muscle mass instead of your fat cells.  However, if you are keeping a nice 200-500 cal deficit or whatever, then having some of that come from cardio will probably mean more of the weight you lose will be fat, not muscle.

Lastly, studies have shown that, for the most part, it doesn’t really matter whether you want to do slow steady-state cardio or HIIT interval-style cardio.  As long as you do the same amount of work, you will burn about the same amount of calories. With steady-state (or LISS), most of the fat will be burned while performing the exercise whereas with something like HIIT, much of the fat will be burned for hours after the exercise. In the end, it just comes down to which type your prefer personally, and which you will be more likely to stick with. If that happens to be dancing in front of your television, so be it.

So now you can see that just by performing cardio, your waistline won’t just magically decrease, especially if your diet isn’t up to par.  Most of whether or not you want to do cardio comes to personal preference.  Do you want to run a bit so that you can eat a little (remember.. a little) more, or do you just not want to eat as much food. If you need to lose A TON of weight, you are much better off dieting the weight off and lifting heavy weights to keep the muscle you have than try to run the weight off.

If you have any comments, questions, or concerns, please leave a comment below. I want to hear from you!