To jog or not to jog
February 15, 2010 9:52 AM   Subscribe

Fit Mefites, please help me understand the importance of including cardio in my workout regimen, as it pertains to reducing body fat percentage!

Guys, I'm confused about this cardio thing. I've tried asking personal trainers, nut-job bodybuilders, and nutritionists and they all give different answers about how it helps a person reduce their body fat!

Some say that it is absolutely completely unnecessary. These are usually the bodybuilders, who I am tempted to believe. The ones I know make a convincing case; they tell me that it's just inefficient to jog for an hour to burn 600 calories when you could just cut 600 dirty calories from your diet. "Don't do cardio, just clean up your diet." When I ask why I couldn't do both, they tell me that doing cardio "steals" calories from your muscle building process and I would just need to eat another 600 calories anyway.

Others say that it is completely necessary no matter what. These are the personal trainers - HIITs on the elliptical burn mad calories, calories equal fat, bad-a-boom. This also makes sense, but a little niggling voice in the back of my head tells me that the body is more inclined to burn muscle rather than fat at any significant calorie deficit. This kind of defeats my purpose of working out, which is to look like a hunky dreamboat rather than an Irish mobster.

And then there's my nutritionist friend, who tells me that it won't make a lick of difference at all as far as fat loss, but I should do it anyway because it's good for the heart. This doesn't help me at all, you goon!

I know how to build the muscle, but I desperately need to lose some fat. Should I go down the cardio path? Or some other voodoo magic?
posted by Willie0248 to Health & Fitness (21 answers total) 20 users marked this as a favorite
 
Different people get fit in different ways and are biased toward the manner in which they got fit.

A bodybuilder burns fat by lifting weights and eating a healthful diet.

A marathoner burns fat by running a lot.

Neither has much to say to the other but each achieves the end goal of being in good physical condition.

There's not really an answer other than that; there are different ways to burn off fat, depending upon what your physical fitness goals are. Start with that question--what are your fitness goals--and someone can tell you the best way to burn fat given those goals.
posted by dfriedman at 9:55 AM on February 15, 2010


Cutting the calories from your diet alone (i.e., not some combination of diet and exercise) is pretty difficult for several reasons. For one thing, it can be difficult to cut a sufficient number of calories while still getting enough vitamins, minerals, protein, etc. For another it's extremely boring and likely to make you hate the whole process. For yet another, if you don't consume enough calories each day your body will resist weight loss.

But perhaps the biggest reason simply cutting calories is difficult in practice is that humans primarily regulate their weight by consuming the same mass of food each day. There are not very many foods that have a low calorie:mass ratio yet are also palatable.

Most studies comparing dieting alone, exercise alone, and a combination find that the combination works better for most people, on average.
posted by jedicus at 10:14 AM on February 15, 2010


You can always, always out-eat a workout program. Any workout program. Weight loss is 80% diet. Get your diet in check, the fat loss will follow.

Cardio and exercise will get your body in better shape--cardio will help out your aerobic capacity, weight training with build muscle mass. But neither will immediately burn a significant number of calories, at least not enough to make a huge fat loss difference (though weight training will build the muscle mass that will eventually slightly raise your metabolic rate).

Really, my recommendation to anyone trying to be healthy though is that you:
1) Fix Diet
2) Fix Diet
3) Find something active you like to do and do that

Because the exercise program doesn't matter if it's not something you enjoy doing and will drop as soon as you have an excuse to do so.
posted by schroedinger at 10:19 AM on February 15, 2010 [4 favorites]


Here's an anecdatal point: I ate like a fucking pig two years ago, did cardio like mad (1 hr swimming, 30 min running, and an hour riding, every day), and won "biggest loser" contest with my family (at almost 19% lost). I had plenty of nutrients and protein, and never felt physically better in my life. When I lost weight ten years ago, via lifting 1.5 hrs/day combined with calorie restriction, I'd either shit three times a day or once every three days, and felt like hell.
posted by notsnot at 10:26 AM on February 15, 2010 [1 favorite]


It never ceases to amaze me that people get confused on this question. At the same time, of course, it makes sense, because there are - as you mentioned - about a kajillion different people out there giving advice, and it all seems to be different and often contradictory. But it really is quite simple and here's how it works:

Net daily calories = calories in - calories out.

Tada! Everything you ever need to know. Right there.

If you eat more calories than you burn, your body will convert those calories to fat for storage. If you burn more calories than you eat, your body will call upon those fat stores already present in your body to make up the difference. You will then be burning fat, lowering your body fat %, and (probably) losing weight. (This depends, of course, on if you are also doing weight training. Muscle is much more dense than fat and even building a little [and if you're a novice you will probably build a lot] can quickly counteract the weight loss from burning fat. But of course, again because muscle is so much more dense you will still be getting trimmer, if not actually weighing much less.) (This also, of course, assumes you have fat reserves. If you don't, then having a negative calorie net is what we call "malnutrition" and will eventually kill you.)

Ok so how do you go about calculating this?

First, figure out your resting metabolic rate. This is the number of calories you will burn just by sitting on the couch doing nothing all day (other than, of course, keeping your body at 98.6 degrees which takes a LOT of energy). This is your starting "calories out" number. Next, take a look at your diet and figure out how many calories you are eating each day. (There are many ways to do this and I'll leave it up to you.) This is your "calories in" number.

Now! Subtract. If you get a negative number you have what we call a calorie deficeit and you probably don't need to do cardio to lose weight. If you have anything even approaching zero or (much worse) a positive number, you will need to do cardio to raise your "calories out" number.

And there you go. It's just that simple.

A couple qualifications:

1) Running isn't, actually, the best way to burn calories from a time efficiency point of view. Our bodies are designed to run. We are evolved to run. Our ancestors were naturally selected based upon their ability to run down antelope. We therefore do it remarkably efficiently and your calorie output while running is, in fact, not all that much higher (on an orders of magnitude scale) than your calorie output while just sitting there. Think about it: 400-500 calories for running an hour? That's, like, a bag of chips. Maybe better to just not eat the chips. Or maybe try swimming. Humans suck at swimming (again from an evolutionary point of view) and it burns calories like crazy.

2) All this comes from a strict weight-loss point of view. From an overall health point of view there is absolutely nothing better that you can do for your body than regular vigorous cardiovascular exercise. If your goal is to live longer and be healthier, then forget the weights entirely and just run. Of course, we all often have other goals in mind (a/k/a chesticles.)
posted by ChasFile at 10:51 AM on February 15, 2010 [1 favorite]


I don't see why this needs to be an either-or question.

Do both. Or rather, do all three -- diet, resistance and cardio. Doing all three will benefit you in different ways and get you to the same hunky dreamboat place. Plain-jane circuit training for the win.
posted by Cool Papa Bell at 10:54 AM on February 15, 2010 [1 favorite]


I think HIIT is the way to go. Psychology Today had an article on High Intensity Interval Training and burning fat:

"Because HIIT's work bouts are performed at full throttle, it takes longer for your metabolism to return to its normal resting rate than with other forms of exercise. This means that up to 24 hours after you work out, you'll still be burning up to 15 percent more calories than if you hadn't exercised."

I also think it's important to do exercises that you haven't been doing, to shock your body and stress it the most. I've seen people doing cardio on the same machines over and over. Then when that workout dropoff point comes, 6 months later back to the same machines, and you're quickly back up to where you were before in terms of how long you can do on the machine. That's not progress, that's your body becoming efficient. This is probably what crossfit people preach. I think it's true. It's why I can play some sports for 3 straight hours, but can't last 10 minutes half doing others.

Take up some new cardio activity you don't normally do.
posted by cashman at 10:54 AM on February 15, 2010 [1 favorite]


It may depend on the kind of fit you're going for. A marathoner and a weight lifter are after very, very different ends of the fitness spectrum. A weight lifter has less use* for cardio than the marathoner, because he's focused on instantaneous power rather than endurance. You're really looking at three things here: body fat, muscle mass, and aerobic endurance. A very fit person will have little of the first, but depending on the nature of their activity will have more of one or the other of the latter two.

*A certain amount of cardio is necessary for weight trainers to help with blood pressure. My father, a cardiologist, has seen more than one over-zealous weight lifter exercise his way into hypertension by not balancing strength training with cardio.
posted by valkyryn at 11:04 AM on February 15, 2010


Have to agree with ChasFile - it is all about net calories. This is basically like the law of conservation of energy in science - i.e. you aren't going to gain weight if you aren't taking in more calories than you burn, as that would be creating mass out of nothing.

Take in more calories than you burn, you will gain weight in some way (whether that way will be mostly muscle or mostly fat depends how much weight lifting you are doing). You will not likely lose fat and gain muscle at the same time (although it can happen a bit for beginners).

Similarly, burn more calories than you take in, and you will lose weight. That weight can be both fat and muscle, but lifting weights and getting enough protein will help ensure that it is mostly fat you are losing.

Cardio is just one way to help increase the amount of calories you output.

Of course there are metabolism factors, and other benefits to consider of various types of exercise, but in terms of pure weight loss/gain, it's all about calories in vs calories out.
posted by Diplodocus at 11:07 AM on February 15, 2010


I guess I forgot to mention the upshot.

The upshot: You need to burn more calories than you eat. You can do this by restricting your calorie intake and sitting on the couch all day (in - out). Or you can do this by eating like a pig and working out like crazy (IN - OUT). Or you can do this by restricting your diet and working out like crazy (in - OUT). Or you can do this by eating a healthier diet and working out moderately (In - Out).

The bigger the calorie deficiet, the greater the fat loss. The first two methods will create weight loss, but probably aren't the healthiest way to go about it. The third method will create dramatic weight loss but will probably feel like a pretty shitty lifestyle if you're not a professional athlete or extremely motivated. The last method is probably best.

Really, like much else in life, this needs to be about goal setting, planning, and managing expectations. 1 gram of fat burned will create 9 calories. So if you divide your calorie deficit by 9 you can get a (very rough) idea of how much fat you can expect to lose each day (there are about 454 grams in a pound). So from a planning point of view: if you want to lose 10 pounds you will need to burn 4,500 grams of fat. That much fat can produce 40,500 calories. So you will need to maintain a daily 400 calorie deficit for 100 days to lose those 10 pounds.

(Note that this is all very, very rough but the idea is to get things realistic for you. If you want dramatic weight loss - on the order of 10 pounds of fat per month or more - then you will need to maintain a fairly dramatic calorie deficit. And that will be hard because you will either be not eating much or working out a lot or probably both.)
posted by ChasFile at 11:11 AM on February 15, 2010 [1 favorite]


This also makes sense, but a little niggling voice in the back of my head tells me that the body is more inclined to burn muscle rather than fat at any significant calorie deficit. This kind of defeats my purpose of working out, which is to look like a hunky dreamboat rather than an Irish mobster.

This is the operative part of your question which nobody has bothered to address. You're not trying to lose weight -- you're trying to reduce bodyfat percentage, i.e. lose fat while maintaining muscle. Conventional wisdom says that this is the best you can do -- it's very difficult or impossible, unless you are overfat and brand new to training, to lose fat while gaining muscle.

Lyle McDonald has a lot to say about this, as do lots of other bodybuilder types because this is in part what they are all about. However, bodybuilder types tend to be full of crap, so some things have to be taken with a grain of salt. In any case, what Lyle seems to be saying is most important is that your diet contains adequate protein (around 1g/pound of bodyweight), that you reduce training volume while maintaining intensity (e.g. you can do less total sets per week but you have to lift as heavy as you did before) and that you run a caloric deficit. I'm not sure how much it matters in the end whether you create that caloric deficit through cardio, diet, or both -- I suspect any of those approaches will work if you can pull it off.

Lots of people will tell you to reduce or cut carbs completely. Some of the reading I've done seems to indicate that this kind of diet can be successful because it leads to increased protein intake, which increases satiety, but ultimately it works because of the reduced calories rather than because of any specific property of carbohydrates. You may want to give it a shot though.
posted by ludwig_van at 11:27 AM on February 15, 2010 [1 favorite]


Lots of people will tell you to reduce or cut carbs completely.

Don't mean to threadmod here but this is a bit of a sore subject for me.

Cutting carbs will work if the only thing you are interested in doing is changing your diet. But dude! You NEED carbs to work out! Your body NEEDS carbs! Eat them! They are delicious!

At rest and during mild exercise, your body burns fat and carbs to get calories at a roughly 50/50 rate. During strenuous exercise (what is called "VO2 Max" - the point at which oxygen is being transfered from your lungs to your blood at your body's maximum rate and therefore is the rough upper bound of your metabolic output and therefore also the rough upper bound of your "go") your body will switch to burning only carbs. It does this because it can release the energy from carbs more efficiently (e.g. using less oxygen) than it can from fat. Because your body cannot supply any more oxygen (you're at VO2 MAX, remember) and yet is still demanding more metabolic output ("I want more go, legs!") the only thing it can do to increase the number of calories it produces is to burn more (or only) carbs and less (or no) fat.

Depending on your diet, fitness, and other factors you can store maybe 500 grams of carbs in your body on any given day. Since each 1 carb gram can produce 4 calories, that's roughly 2,000 calories of pure carb energy floating around. This is, again depending on your athleticism and metabolism, roughly 18-20 miles of running (3 to 4 hours at a solid pace, at the 500-600 calories per hour that jogging takes). So if your body is burning only carbs because you are at VO2Max for that period of time, at around 18-20 miles you will have burned those 2,000 stored carb calories and your energy source will simply be exhausted. And therefore, so will you. This is what marathoners call "The Wall." (Incidentally this is also the idea behind carbo-loading. If you can manage to store more than your ordinary 500 grams of carbs in your body on race day, you'll hopefully push the wall out to somewhere past the finish line. Hopefully.)

Once you hit the wall you will be physically unable to continue, and the only way to get past it is to slow down your metabolism and work out at less than VO2 Max so that your body can start burning some energy from fat again. This is why marathoners have to train by running 20+ miles (e.g. past the wall) at least once a week - because they need to train their bodies to not go into carb-only burning "panic mode" even though they are doing strenuous exercise. This is also the reason that if you are only interested in burning fat you should (somewhat counter-intuitively) not go full speed but instead aim for a target heart rate of 60-80% your Max. If you train at 80-100% your Max rate and are not a marathoner, odds are you are only burning carbs and not fat.

The point of all that is this: if you severely restrict the amount of carbs in your diet you will severely shorten the distance between the starting line and the wall. So if you are doing any kind of cardio exercise I urge urge urge you to not do that Atkins diet nonsense. [snarky but kinda true] It's only for fakers who are interested in changing their diet but not interested in actually working out or getting healthy. [/snarky but kinda true]
posted by ChasFile at 11:59 AM on February 15, 2010 [8 favorites]


So if you are doing any kind of cardio exercise I urge urge urge you to not do that Atkins diet nonsense. [snarky but kinda true] It's only for fakers who are interested in changing their diet but not interested in actually working out or getting healthy. [/snarky but kinda true]

I really have no dog in the fight re low-carb diets, and I'm no CrossFit evangelist, but low-carb seems to work pretty well for lots of CrossFitters, and they certainly work out.
posted by ludwig_van at 12:05 PM on February 15, 2010


"This also makes sense, but a little niggling voice in the back of my head tells me that the body is more inclined to burn muscle rather than fat at any significant calorie deficit."

Your body doesn't "want" to burn muscle unless you are short of protein (and unless you're on a crash diet or doing crazy-lots of exercise, few first-worlders are). An introductory college nutrition textbook can show you the process of calorie storage (most energy is from breaking food down into glucose, and then storing it as fat if you have too much ... it's not as simple as "eating fat makes body fat," your body is excellent at converting fat and sugar back and forth; protein is a little more complicated) and what the nutrients are used for in the body. Understanding that process, which is probably 20 pages of reading, will help you think more critically about random (and frequently wildly false) nutrition and exercise information from non-experts, and help you decide how to manage your own nutrition and exercise.

When calories in are fewer than calories out, you will burn fat. It takes 3500 calories to make up one pound of fat, so a daily deficit of 500 calories will burn about a pound of fat a week. Whether you find that 500 calories in diet or exercise or both is up to you; the best plan is the one you can stick with.
posted by Eyebrows McGee at 12:08 PM on February 15, 2010 [1 favorite]


Regarding the cardio vs just-eating-less argument: I try to keep my calorie intake under a certain quota I set. I consider this to be my "primary" weight-loss method.

However, sometimes, I mess up. Maybe I didn't realize how many calories were in something, maybe I forgot I ate something and didn't add it to my calculations, or maybe I just really wanted to eat despite knowing I shouldn't.

What do you do then? Just write off your diet for the day as failed? When I discover I've gone over my quota, that's when cardio is really helpful. A lot of the time if I'm 300-400 calories in the red, I can go to the gym and a 45-60 minute workout will bring me daily total back down to where it's supposed to be. Of course, I try not to rely too much on this method, as sometimes I can't get to the gym, or I have a bad workout. But it does function decently as a sort of "safety net" for when my diet fails.

YMMV.
posted by Vorteks at 12:25 PM on February 15, 2010


What's being missed here is that a cardio workout is a muscular workout as well, specifically for your heart. There are all kinds of reasons, especially if your family has any kind of history with heart problems, to keep your heart strong and worked out continually.

Also, you can set up a weight lifting regimen that keeps your heart rate in cardio levels for 30+ minutes pretty easily, so I think the running vs. swimming vs. lifting weights argument is a little misleading. A pretty fun workout I do is 10-15 minutes on some type of cardio machine (rarely the treadmill, most often the elliptical or arc trainer or stair master) and then hit the weights, rotations of 3 machines with few breaks to keep the heart rate up, for another 30 minutes or so.

One thing that I've heard quite a bit, including from both my trainer and former marathon coach, is that it's hard to get in shape/build muscle at the same time that you're aiming to lose weight, for all the reasons that you and others have listed. Pick your goal. If you want to lose weight, focus on that first. Then get into some serious shape. Or vice versa.
posted by kryptonik at 1:07 PM on February 15, 2010 [2 favorites]


Not to directly contradict ChasFile, but I'm having absolutely zero problems dropping weight doing low-carb and 30 minutes of cardio (jogging) 3-4 times a week. He seems pretty sure of himself, but I'd take it with a grain of salt.
posted by logicpunk at 1:12 PM on February 15, 2010 [2 favorites]


Sorry, but I'm with your nutritionist. Not so much the "it won't help with weight loss" part, but rather with the "it's good for other reasons and you need to do it anyway" part.

Cardio isn't all about weightloss. It's about getting your cardiovascular system -- your heart and lungs -- in shape. And you know what? That matters, not just because it might help you avoid a heart attack or stroke, and not just for those people who want to, say, run a marathon.

-- On vacation and walking all day around a European city?
-- Running to catch a plane?
-- Have a small child to run around after?
-- Invited by cute girl/guy to go for a 5 mile hike?
-- Have to travel for work, give a presentation, have meetings all day, and fly home that night?
-- Etc.

Cardio helps with ALL THAT STUFF. Maintaining a basic level of cardiovascular fitness makes life easier. (Ditto strength -- one reason I do a little weightlifting is simply so that I can always put my own damn bag in the overhead bin, thankyouverymuch. But the OP wants to know about cardio.)
posted by kestrel251 at 1:17 PM on February 15, 2010 [3 favorites]


Also not to contradict ChasFile since he probably knows oodles more than I do, but my anecdotal experience is that I'm doing a very low-carb high protein diet, and working out harder than I ever have in my life, with no problems hitting "the wall."

I'm not running 18-20 miles a day, but I do 30 mins HIIT cardio 3 days a week, strength training 30 mins twice a week, and 2 hour INSANELY intense bootcamp workouts every saturday morning. I notice a slight energy decrease compared to when I ate regular amounts of carbs, but no wall-hitting to date. Just my experience.
posted by egeanin at 3:25 PM on February 15, 2010


Low or no carb diet has been around a lot longer than Atkins. If you look up the literature, scientist were doing studies on it 70+ years ago. There is a lot of data backing it up, and more than enough empirical data to show that it works.

Anyway, it's already been said but for anyone attempting to get in "shape", whatever that may be, diet comes first. Then the program. Modifying your diet, assuming that your coming from an unmodified diet, will (or at least should) always come down to changing both your macro-nutrient and caloric intake. There are plenty of diets and programs already tailor made for what you want, so set a goal and go for it.
If I were to give you advice of a broad generalization type, and not knowing thing one about anything you eat or whatnot, I would tell you that (subtracting out the roided/GHed/diuretic-ed bodybuilder freaks) the biggest and most ripped dudes are the guys who usually participate in explosive type movements frequently.

I suppose I should say people as that applies to women as well.
posted by P.o.B. at 10:45 PM on February 15, 2010


Whether or not cardio drips off the fat, cardio's other benefits should convince you that you need some cardio in your life.
posted by kaizen at 7:38 AM on February 16, 2010


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