We’ve all seen those endurance athletes–the marathoners and triathletes. Thin and wiry, as lean as they come, with hardly any fat on their lithe bodies.  And even those of us who don’t think we’ll ever look like that (or don’t aspire to be have that sinewy thin physique) have long thought that with enough training, we too might “lean out” to some degree.

But apparently, as I’ve learned over the past year or so, that’s actually not guaranteed to be the case. There is in fact all sorts of evidence that endurance training will not produce that distance runner’s body in anyone who is not already genetically predisposed to have it.

But even more frustrating, lots of people are saying that it won’t even help you lose weight.  That seems contrary to what we’ve always thought.  But there it is. The culprit is ‘steady state cardio.’  I’m not promising a comprehensive post about it today. But I am going to tell you what I’ve learned so far.

It used to be that we were recommended to train in the “aerobic zone” if we wanted to “burn fat.” The thinking when I first encountered this in the late-80s/early-90s was that if you worked out in that zone, you’d burn mostly fat. Here’s a version of that view from an article I found on Livestrong:

If you are just beginning a fitness program, or if you are warming up, your heart rate should be 50 to 60 percent of your MHR. Once you achieve a measure of physical fitness, you should increase your pace until your heart rate is in the 60 to 70 percent of MHR range. At these levels of aerobic exercise intensity, about 85 percent of the calories you burn come from fat and you gain significant cardiovascular benefits.

The same article goes on to say that if you are training for a marathon or some other endurance sport, you’ll need to pick up the pace a bit:

you’ll need to move your aerobic exercise up to the 70 to 80 percent of MHR range. In this “training zone” you burn more calories, although only 50 percent come from fat. You build your endurance and level of cardiovascular fitness.

See how the fat burning changes when you do that?  So that’s hint number one that burning more calories doesn’t necessarily make you thinner and leaner.

Exhibit two:  an email conversation with my Precision Nutrition coach. She said that my triathlon training may involve goals that are, in her words, “opposite” to the goals of changing my body composition through getting leaner.  That’s the first time I’ve heard it put in such strong terms. To me, “opposite” means something that goes in the exact other direction.  The opposite of getting leaner would be gaining fat.

While I am not obsessed with body composition, it is not my goal to change my body composition in the direction of a higher fat percentage and lower lean mass percentage.  I wouldn’t have signed up for the Lean Eating program if I wanted to do that. Between menopause and a sweet tooth, that was happening all on its own!

But don’t shoot the messenger, I told myself. The coach is simply saying that if I’m replacing weight training with endurance training, I’m not going to see the same gains in lean mass that the weight training workouts are designed to achieve AND my endurance training is going to in fact use my lean mass as fuel at least some of the time (50% if the Livestrong article is right).

That was enough to convince me not to replace weight training sessions with endurance training too many times. I’m trying to fit them all in and have added intervals to the steady state training.

I’m not sure why it should surprise me that there is no tight link between training and fat loss.  It’s just the flipside of what Sam blogged about in her post about the not-as-simple-as-we-like-to-think link between inactivity and obesity.

In a holier-than-thou article targeted at women (title: Why Women Shouldn’t Run), we’re told why steady-state cardio runs counter to fat loss goals, based on the body’s adaptablity:

Nothing exemplifies this increasing efficiency better than the way the body starts burning fuel. Training consistently at 65 percent or more of your max heart rate adapts your body to save as much body fat as possible. After regular training, fat cells stop releasing fat the way they once did during moderate-intensity activities[32-33]. Energy from body fat stores also decreases by 30 percent[34-35]. To this end, your body sets into motion a series of reactions that make it difficult for muscle to burn fat at all[36-41]. Instead of burning body fat, your body takes extraordinary measures to retain it.

But is running actually bad for you?  A guest poster on Go Kaleo responded to “Why Women Shouldn’t Run” by noting that, last she checked, running was actually good for you. She does a very careful analysis of the article and the citations contained in it. She says that in one of the articles cited, there is important information that challenges the above conclusion:

Paper 42 is a case study on a woman who ran 4500 miles across Canada over the course of 112 days (equivalent to 1.5 marathons a day). She did indeed lose lean body mass (LBM – which includes more than just muscle mass), nearly 7 lbs worth. She also lost just less than 30 lbs of fat. Averaging 8 hours of running a day, for almost three months, on a 1000 calorie/day deficit, this woman is doing everything the author is ranting against. Yet, amazingly she managed to lose a considerable amount of fat even though she must surely be below the T3 threshold established earlier. It’s unfortunate her thyroid levels were not also monitored.

I’ve blogged before about the “famine response” and metabolic health. It sounds a lot like the survival mode the critic of running talks about. In another article, entitled “Does Running Make You Fat–Debunked,” the author points out that you could run into trouble if you don’t eat enough to sustain your training.

Another frequently cited reason for endurance training getting int he way of fat loss is that it apparently makes us eat more.  An article about endurance training and “fat-loss myths” says:

Often, the more you exercise, the hungrier you get and 1) the more you will eat, or 2) the more you believe you “deserve” to eat for having survived the killer workout. Unfortunately, rewarding yourself with a 600-calorie cinnamon roll can quickly erase in a few minutes the 600-calorie deficit you generated during your workout.

But surely that can’t be the whole story either. We need to eat properly if we’re endurance training, and that means eating more than we would if we weren’t endurance training. Again, that will protect our metabolic health.

And what about cortisol, that hormone associated with stress? It comes up a lot in these discussions because, apparently, it triggers the survival response and it’s been found that athletes have higher levels of it in their bodies than other people. According to this article, we can’t conclude from that that endurance training is bad for our health. The researchers say that:

Enough is known about the many positive health effects of endurance training to say without qualification that, on balance, it is extremely beneficial to overall health. And since endurance training has been shown to specifically reduce abdominal fat storage, improve, brain function and (except in cases of overtraining) enhance immune function, we can also say that high cortisol levels in endurance athletes do not have the same health implications that they have in non-athletes.

And not too long ago the Australian Runner’s World website, in a somewhat misleadingly-titled article, “Your Runner’s Body in Just 6 Weeks,” had this to say:

You don’t see many overweight runners, and there’s a good reason for this. The simple act of putting one foot in front of the other is the best way to shift excess kilos. An average 70-kilogram [154 pounds] person running at steady 5:37-per-kilometre pace burns a pizza-absolving 3238 kilojoules [773 calories] in an hour, compared with, say, 2062 kilojoules [493 calories] when cycling.

And, according to a study at Yale University School of Medicine, US, running’s metabolic boost means that if you run for four hours a week, you’ll melt more kilojoules than non-runners, even when you’re not running.

 

All this is to say that it’s not conclusive that running or other endurance training literally makes us gain fat.  But it’s also not the case that running marathons will give anyone the body of a marathoner.  That would be like playing basketball to get tall and lanky. It just doesn’t work that way. And that’s why the Australian article is misleading.

Of course, your runner’s body could just be the one you run with, much like your beach body is the one you take to the beach.  But the article is suggesting otherwise. The plan it recommends, encouraging high intensity interval training, is very good, but it’s not going to get anyone the “runner’s body” that we associate with elite endurance athletes.

For me, the take-away point is simply that whatever I do, I want to enjoy doing it.  We’ve talked a lot about performance goals and why they’re good motivators. Over the past year, I’ve certainly found this to be true.  I’m loving what I’m doing, which is why it’s frustrating when I hear things like “women shouldn’t run.”I do want to do endurance sports, especially triathlon.

And I’m glad that I have goals beyond fat loss.  And if I’ve learned anything over the past year and a bit since we started the blog, it’s that there is no set training routine that will achieve the same results for everyone who does it.  That’s why it’s more important than ever to choose activities that we enjoy and that make us feel good, whatever body type we happen to have.