Tag Archives: aerobic

Cardio Lowers RMR – A Fairy Tale


by Jose Antonio PhD FNSCA FISSN. Today’s story is entitled “Cardio lowers RMR – A Fairy Tale.”

Key Points to Remember

  • There is a plethora of scientific evidence, which demonstrates that regular aerobic training has no effect on RMR. Some studies actually find an increase.
  • Resting energy expenditure is largely a function of body weight and FFM.[1, 2]
  • Cardio has become the “carbs of the fitness world.” – Shawn Arent PhD, Rutgers University
  • If you like doing cardio, don’t let some fitness guru talk you out of it.
  • If you hate doing cardio, then for Pete’s sake, don’t bitch about those who do it.
  • If you want to elevate your RMR, gain weight, especially skeletal muscle weight.
  • RMR is by itself a meaningless measure for the performance sports.
  • If you compete in football, baseball, basketball, cycling, volleyball, rowing, surfing, paddling, gymnastics, soccer, hockey, track and field (pick one) or frickin’ tiddlywinks, measuring RMR is about as useful as selling bikinis to Russian women in Siberia.

Social Media Silliness

So what is it about aerobic training (i.e., ‘cardio’) that has gotten the ire of so many fitness professionals? Cardio makes you fat? Yep. And there really is a pot of gold at the end of the rainbow. For my take on the ’cardio makes you fat’ baloney, read this piece from the ISSN Scoop: http://www.theissnscoop.com/cardio-makes-you-fat-and-apples-will-rise/

Supposedly cardio, especially the lower intensity variety, will lower your resting metabolic rate Beach walking(RMR) faster than a New Yorker can flip you the birdie. So I guess if you go for a walk on the beach after pigging out on beer and chicken wings, your metabolic rate will magically drop?

Let’s say you and your significant other visited the Sunshine State (that’s Florida for those who flunked 7th grade geography). Every morning for a week, you walk hand-in-hand up and down the beach. Sometimes you’d walk for more than an hour. Would your RMR drop because of this dreaded low intensity cardio? Are all these beach walkers killing their RMR? To quote the former #1 tennis player and part-time brat on the court John McEnroe, “You can NOT be serious!”

johnnymac_zps31f826d7Easy enough. So what does the science say on cardio and RMR? Below are a series of abstracts that I’ve shortened and added my pithy comments. It’ll give you a snapshot of the literature as it relates to exercise training and RMR. I’ve highlighted the parts that are of interest to those of you with the attention span of a mosquito.

Study #1 – This study examined resting metabolic rate (RMR) and thermic effect of a meal (TEM) among athletes who had participated in long-term anaerobic or aerobic exercise. Nine collegiate wrestlers were matched for age, weight, and fat-free weight with 9 collegiate swimmers. RMR adjusted for fat-free weight was not significantly different between groups. Thus, it doesn’t matter if you engage in long-term aerobic and anaerobic exercise training; resting energy expenditure is not different between these college athletes.[3] So whether you want to swim in chlorinated water or wrestle someone who smells like dirty socks soaked in vinegar, it don’t matter. RMR won’t be adversely affected.

Study #2 – Eight moderately obese women took part in an 11-week training program, including 5 hours of aerobic exercise per week performed at a mean intensity of about 50 percent VO2 max. Now that my friends is frickin’ low intensity. Fifty percent max VO2 is like a walk in the park. So what happened? Oddly enough, the results showed that exercise-training induced a significant rise in RMR. In fact, this study showed an elevated RMR per unit of fat free mass in both lean and moderately obese individuals.[4]running

Study #3 – Thirty-one women (mean age 35 yr) who were overweight were matched and randomly placed into a control group (CON), a diet-only group (D), a diet+aerobic endurance exercise training group (DE), or a diet+aerobic endurance exercise training+strength training group (DES). Can you keep track of that? That’s a lot of groups. So after 12 weeks, the three dietary groups demonstrated a significant loss in body mass, % body fat, and fat mass. No differences were observed in the magnitude of loss among groups, in fat-free mass, or in resting metabolic rate.[5] So even though aerobic training plus diet resulted in a loss of weight and fat mass, there was no change in RMR. Hmmm.

Study #4 – The effects of either 12-wk of high-intensity endurance or resistance training on resting metabolic rate (RMR) were investigated in 47 males aged 18-35 years. Subjects were randomly assigned to either a control (C), resistance-trained (RT) or endurance-trained (ET) group. After training both exercise groups showed significant declines in relative body fat either by reducing their total fat weight and maintaining fat-free weight (ET) or by reducing their total fat weight and increasing fat-free weight (RT). RMR did not significantly change after either training regimen. These results suggest that both endurance and resistance training may help to prevent an attenuation in RMR normally observed during extended periods of negative energy balance (energy intake less than expenditure) by either preserving or increasing a person’s fat-free weight.[6]

Study #5 – Investigators determined the effects of aerobic exercise training and resistance exercise training and the incremental effect of combined aerobic and resistance exercise training on resting metabolic rate (RMR) in previously sedentary individuals with type 2 Cycling_20-2diabetes. One hundred and three participants were randomly assigned to four groups for 22 weeks: aerobic training, resistance training, combined aerobic and resistance exercise training, or waiting-list control. Exercise training was performed three times per week at community-based gym facilities. RMR did not change significantly in any group after accounting for multiple comparisons despite significant improvements in peak oxygen consumption and muscular strength in the exercising groups. Adjusting RMR for age, sex, fat mass, and fat-free mass in various combinations did not alter these results. These results suggest that RMR was not significantly changed after a 6-month exercise program, regardless of modality, in this sample of adults with type 2 diabetes.[7] Geez. Is there a pattern here? Isn’t cardio supposed to make you fat? Ooops, I mean lower RMR?

Study #6 – Sixty-five healthy, weight-stable women, aged 21-35 or 50-72 years, were studied: 12 premenopausal and 15 postmenopausal sedentary women, 13 premenopausal and 15 postmenopausal distance runners, and 10 endurance-trained postmenopausal swimmers. RMR was measured by indirect calorimetry (ventilated hood system) after an overnight fast, and values were adjusted for fat mass and fat-free mass. Our results are consistent with the concept that the age-related decline in RMR in sedentary women is not observed in women who regularly perform endurance exercise. The elevated level of RMR observed in middle-aged and older exercising women may play a role in their lower levels of body weight and fatness compared to those in sedentary women.[8] Wait, did I read that correctly? Women who performed dreaded cardio actually were able to fight the age-related drop in RMR.

Study #7 – This study investigated the effects of 12 weeks of aerobic exercise plus voluntary food restriction on the body composition, resting metabolic rate (RMR) and aerobic fitness of mildly obese middle-aged women. The exercise/diet group participated in an aerobic training rowingprogram, 45-60 minutes daily at 50%-60% of maximal oxygen uptake (VO2max), 3-4 days per week, and also adopted a self-regulated energy deficit relative to predicted energy requirements. After the regimen had been followed for 12 weeks, the body mass of the subjects had decreased by an average of 4.5 kg, due mainly to fat loss, with little change of fat free mass (mff). The absolute RMR did not change, but the experimental group showed significant increases in the RMR per unit of body mass (10%) and the RMR per unit of mff (4%). The increase in RMR/mff was not correlated with any increase in VO2max/mff. The resting heat production per unit of essential body mass increased by an average of 21%, but the resting heat production rate per unit of fat tissue mass remained unchanged. We concluded that aerobic exercise enhances the effect of moderate dietary restriction by augmenting the metabolic activity of lean tissue.[9] Huh? Regular aerobic exercise increases RMR per unit body weight. Get on that treadmill! Ok, not really. Treadmill running is as much fun as wrestling a porcupine.

This pic has nothing to do with cardio. Just thought you'd like it. :-)

This pic has nothing to do with cardio. Just thought you’d like it. :-)

Study #8 – Scientists examined the effect of a 12-wk endurance exercise training program on RMR and 2) to provide insight into the mechanisms responsible for alterations in RMR that may occur after exercise training. Male participants (19-32 years) in an exercise group (EX) performed jogging and/or running 3-4 days per week, 25-40 min per session, at 60%-80% VO2max, whereas subjects in a control group (CON) maintained their normal activity patterns. Body composition, VO2max, RMR, epinephrine, norepinephrine, total thyroxine, free thyroxine, insulin, free fatty acids, and glucose were measured before and after the intervention.Training resulted in a significant increase in VO2max in EX. Absolute and relative values for RMR did not significantly change in EX (endurance training group) after training. Mean values for epinephrine, norepinephrine, total thyroxine, insulin, and glucose did not significantly change in either group; however, free thyroxine decreased significantly after training in EX. Oddly enough, RMR in CON decreased significantly when expressed as an absolute value and relative to body weight, fat-free mass, and fat mass. The mechanism for the decrease in CON is unknown, but it may be related to seasonal variations in RMR. Training may have prevented a similar decline in RMR in EX and may be related to a training-induced increase in fat oxidation.[10]

Study #9 – We tested the hypothesis that resting metabolic rate (RMR) declines with age in physically active men (endurance exercise > or = 3 times/wk) and that this decline is related to weekly exercise volume (h/wk) and/or daily energy intake. Accordingly, scientists studied 137 suzy_favor_hamilton4-getty_1356117573_540x540healthy adult men who had been weight stable for 6 months or longer. What they found was fascinating: 1) RMR, per unit FFM, declines with age in highly physically active men; and 2) this decline is related to age-associated reductions in exercise volume and energy intake; 3) this does not occur in men who maintain exercise volume and/or energy intake at a level similar to that of young physically active men.[11] So that’s the secret. Exercise a lot (even cardio is good) and eat a lot. My kind of program!

Study #10Is a 1-year study long enough for you? Let’s find out. Seventeen sedentary participants completed a 12 months jogging/walking program, 3 days/week for 45 min/session at a constant heart rate (HR) prescription of 60% HR-reserve. That’s pretty easy cardio if you ask me! After 12 months of training, body weight remained unchanged; however, body fat was significantly reduced by 3.4 %. Neither RMR nor substrate oxidation at rest changed significantly. In summary one year of recreational endurance training does NOT negatively impact RMR.[12] I know I know. Naysayers will say “that study isn’t long enough.” “We need a 10 year study to verify these results.” Blah blah blah.

Study #11 – Scientists determined whether chronic (9 months) moderate-intensity exercise training changes resting metabolic rate (RMR) and substrate oxidation in overweight young adults. Participants were randomly assigned to non-exercise control (CON, 18 women, 15 men) or exercise (EX, 25 women, 16 men) groups. EX performed supervised and verified exercise 3-5 d/week, 20-45 min/session, at 60-75% of heart-rate reserve. Here’s what happened. EX men had significant decreases from baseline to 9 months in body mass (94.6 to 89.2 kg) and percent fat outrigger-canoe(28.3 to 24.5). CON women had significant increases in body mass (80.2 to 83.2 kg) from baseline to 16 months. VO2max increased significantly from baseline to 9 months in the EX men and women. RMR increased from baseline to 9 months in EX men and women. So there you have it. Regular moderate-intensity exercise in healthy, previously sedentary overweight and obese adults increases RMR but does not alter resting substrate oxidation. Women tend to have higher RMR and greater fat oxidation, when expressed per kilogram fat-free mass, than men.[13] That’s interesting. Women have a greater RMR per kg FFM than men. Hmmm. So women have no excuse for packing on the lbs. 😛

Study #12 – Maybe it does decrease RMR? Scientists examined the effects of exercise training on resting metabolic rate (RMR) in moderately obese women. Nineteen previously sedentary, moderately obese women (age = 38.0 years, percent body fat = 37.5) trained for 20 weeks using either resistance training (RT) or a combination of resistance training and walking (RT/W). The high intensity resistance-training program was designed to increase strength and fat-free mass and the walking program to increase aerobic capacity. There was also a non-exercising control Helga paddling SUPgroup (C) of 9 subjects in this study. Fat-free mass was significantly increased in both the RT (+1.90 kg) and RT/W (+1.90 kg) groups as a result of the training program. So apparently adding walking to weight training does not negatively impact gains in LBM. No group showed significant changes in fat mass or relative body fat from pre- to post-training. This runs counter to the ubiquitous advice of weight training being a superior method of achieving fat loss. Furthermore, aerobic capacity was slightly, though significantly, increased in the RT/W group only. The RT group showed a significant increase (+44 kcal per day), while the RT/W group showed a significant decrease (-53 kcal per day in resting metabolic rate post-training. RT can potentiate an increase in RMR through an increase in fat-free mass, and the decrease in RMR in the RT/W group may have been a result of heat acclimation from the walk training.[14] This study shows a difference. Though I’d posit that the lower RMR is made up for by the extra walking in the resistance training plus walking group. Besides, isn’t weight training supposed to combat the effects of a lower RMR?

So in conclusion: The preponderance of the evidence clearly shows that regular aerobic training has little to no effect on RMR. So you can put the notion of ‘cardio lowering RMR’ in the trash bin where it’ll join the ‘cardio makes you fat’ dopiness. So if you love cardio, keep doing it. It’s not going to ‘ruin’ your metabolism. If you want to increase RMR, then lift weights and gain LBM. On the other hand, if you exercise too much, eat too little, and lose body weight and lean body mass, then your RMR will drop. But who in their right mind does that?

BIO – Jose Antonio PhD is the CEO of the ISSN, www.issn.net and faculty at Nova Southeastern University in Exercise and Sports Science. I’m not fond of doing cardio in a gym. Why anyone would run on an indoor treadmill, do that silly elliptical or ride a bike (oh..I mean do Spinning classes…haha) in a room full of stinky people at your local gym is as puzzling as watching a fat man order a diet coke with a slice of cheesecake. Go outside for chrissakes. It’s a helluva lot more fun.

Paddle in VA Beach 2016 edited


1.         Taguchi M, Ishikawa-Takata K, Tatsuta W, Katsuragi C, Usui C, Sakamoto S, Higuchi M: Resting energy expenditure can be assessed by fat-free mass in female athletes regardless of body size. J Nutr Sci Vitaminol (Tokyo) 2011, 57:22-29.

2.         Deriaz O, Fournier G, Tremblay A, Despres JP, Bouchard C: Lean-body-mass composition and resting energy expenditure before and after long-term overfeeding. Am J Clin Nutr 1992, 56:840-847.

3.         Schmidt WD, Hyner GC, Lyle RM, Corrigan D, Bottoms G, Melby CL: The effects of aerobic and anaerobic exercise conditioning on resting metabolic rate and the thermic effect of a meal. Int J Sport Nutr 1994, 4:335-346.

4.         Tremblay A, Fontaine E, Poehlman ET, Mitchell D, Perron L, Bouchard C: The effect of exercise-training on resting metabolic rate in lean and moderately obese individuals. Int J Obes 1986, 10:511-517.

5.         Kraemer WJ, Volek JS, Clark KL, Gordon SE, Incledon T, Puhl SM, Triplett-McBride NT, McBride JM, Putukian M, Sebastianelli WJ: Physiological adaptations to a weight-loss dietary regimen and exercise programs in women. J Appl Physiol (1985) 1997, 83:270-279.

6.         Broeder CE, Burrhus KA, Svanevik LS, Wilmore JH: The effects of either high-intensity resistance or endurance training on resting metabolic rate. Am J Clin Nutr 1992, 55:802-810.

7.         Jennings AE, Alberga A, Sigal RJ, Jay O, Boule NG, Kenny GP: The effect of exercise training on resting metabolic rate in type 2 diabetes mellitus. Med Sci Sports Exerc 2009, 41:1558-1565.

8.         Van Pelt RE, Jones PP, Davy KP, Desouza CA, Tanaka H, Davy BM, Seals DR: Regular exercise and the age-related decline in resting metabolic rate in women. J Clin Endocrinol Metab 1997, 82:3208-3212.

9.         Shinkai S, Watanabe S, Kurokawa Y, Torii J, Asai H, Shephard RJ: Effects of 12 weeks of aerobic exercise plus dietary restriction on body composition, resting energy expenditure and aerobic fitness in mildly obese middle-aged women. Eur J Appl Physiol Occup Physiol 1994, 68:258-265.

10.       Lee MG, Sedlock DA, Flynn MG, Kamimori GH: Resting metabolic rate after endurance exercise training. Med Sci Sports Exerc 2009, 41:1444-1451.

11.       van Pelt RE, Dinneno FA, Seals DR, Jones PP: Age-related decline in RMR in physically active men: relation to exercise volume and energy intake. Am J Physiol Endocrinol Metab 2001, 281:E633-639.

12.       Scharhag-Rosenberger F, Meyer T, Walitzek S, Kindermann W: Effects of one year aerobic endurance training on resting metabolic rate and exercise fat oxidation in previously untrained men and women. Metabolic endurance training adaptations. Int J Sports Med 2010, 31:498-504.

13.       Potteiger JA, Kirk EP, Jacobsen DJ, Donnelly JE: Changes in resting metabolic rate and substrate oxidation after 16 months of exercise training in overweight adults. Int J Sport Nutr Exerc Metab 2008, 18:79-95.

14.       Byrne HK, Wilmore JH: The effects of a 20-week exercise training program on resting metabolic rate in previously sedentary, moderately obese women. Int J Sport Nutr Exerc Metab 2001, 11:15-31.


Cardio Makes You Fat and Apples Will Rise


By Jose Antonio PhD FNSCA FISSN 

Key Points To Memorize for the ‘Cardio Makes You Fat’ Crowdsm_cardio-fat-banner

  • Longitudinal training studies of fat kids shows that aerobic training results in a loss of body fat.
  • Longitudinal training studies of fat adults shows that aerobic training results in a loss of body fat.
  • Those who do the most cardio over a 15- to 20-year period exhibit the lowest levels of body fat.
  • Athletes that are engaged in highly aerobic exercise have single digit body fat percentages.
  • Triathletes with a higher training volume have a lower % fat than those with a lower training volume.
  • Cardio does not make you fat.
  • Eating too much makes you fat.
  • Sitting on your ass all day makes you fat.
  • Your brain is comprised mainly of fat.  (This has nothing to do with the article but it is a fun fact).

After seeing another headline of “Does Cardio Make You Fat?” with the answer that ‘of course it does,’ I felt an urge to get off my couch, hit the pause button on “The Blacklist,” (awesome show BTW), and remind people that there is something called “science” that can actually answer that question. “I’m not sure why cardio has become the carb of the exercise world” says Rutgers professor Shawn Arent PhD.  And Dr. Arent hates cardio like rats hate cats, cats hate dogs, and dogs hate Michael Vick.

Pauline loves lifting heavy things, doing cardio and drinking coffee. She'll kick your ass too.  Ok maybe not.

Pauline loves lifting heavy things, doing cardio and eating Swedish meatballs. Ok. I made the meatball part up.

What the heck happened to folks actually reading the scientific literature? You know. Those studies in which scientists actually measure body fat. Instead folks fall hook, line and sinker for this pettifogging bullshit of how cardio affects your appetite, cortisol etc. If the claim is that ‘cardio makes you fat,’ the ONLY measure that matters is whether it makes you fat. Guess what? You need to measure body fat. It reminds me of these acute feeding studies that use whey, casein, amino acids etc. that try to extrapolate how much muscle you’d gain in the long run by looking at acute changes in muscle protein synthesis. I have a better idea. Why don’t you actually measure muscle or lean body mass after a treatment period that matters (ex. 8-12 weeks)? Getting back to my original point, imagine how boring the world would be without carbs or cardio?  You couldn’t eat donuts, take walks on the beach, or do both at the same time.

When did doing cardio suddenly become bad for fat loss?  The boneheads who write these articles should at least make a feeble attempt to read the literature. A simple search on Pubmed cross-referencing ‘aerobic’ with ‘body composition’ shows 517 publications.  There are umpteen other searches of key words you can perform. I’m certain there’s at least one study that’s looked at whether cardio turns you from a lean mean kale-eating machine to a fat slob who dreads the day that buffets are outlawed by Congress.

So what gives? Why has the ‘cardio makes you fat camp’ become so entrenched among a few vocal gurus in the fitness industry? Answer: I haven’t an f’in clue.

Anyhow, let’s harken back to when Ronald Reagan was the President of the USA; that’s the 1980s for those who flunked US History.  Twelve weeks of doing aerobic dance training (3 days per week for 45 min) resulted in “…significant increases in lean body mass and body density, together with decreases in percentage body fat and the sum of four skinfold thicknesses…”[1] Holy smokes did you read that?  They lost weight and fat doing aerobic dance no less. Hmmm.


President Clinton should have done more cardio and less McDonalds.

Let’s fast forward to when Bill Clinton was America’s Commander-in-Chief. In this particular study, 60 Japanese women (~51 years of age) participated in a 3-month weight-loss program consisting of two groups: aerobic dance group and jogging and/or cycling group. Guess what, whether you dance, jogged or cycled, you lost body weight and body fat.  The study’s authors stated “low impact aerobic dance is as useful as jogging or cycling in improving body composition and aerobic power for mildly obese middle-aged women.”  Whoa Nellie.  Isn’t cardio supposed to make you fat?[2]

What happens to fat kids who are put on an aerobic exercise program? Inquiring minds want to know. Scientists put 28 obese children (16 boys, 12 girls; aged 12-14 years) into an exercise group or control group. The exercise group participated in 16-week aerobic exercise program (four 60-min sessions per week at 70-85% of HRmax), in addition to the school’s physical education. So did the fat kids get fatter? Uh no. The kids who did aerobic exercise not only demonstrated a smaller waistline (time to buy new belts), but they also showed a significant drop in fat mass.[3]

Now let’s get a bunch of fat adults and see what happens? In this study, science nerds determined the effect of aerobic exercise, without energy restriction, on weight loss in sedentary overweight and obese men and women. The key words being ‘without energy restriction.’ Thus if cardio truly makes you a porky pig, then it would happen in this study.

Participants were randomized into a 400 calorie/session, a 600 calorie/session or to a non-exercise control. Exercise was supervised, 5 days/week, for 10 months.  Now if we use the sterling logic of the ‘cardio makes you fat’ crowd, then one would predict that the 600-calorie/session group would be the fattest at the end of the study, correct?  Well, good thing we have science to answer this question and not some voodoo-witch doctor-fitness guru bullshit.  What happened? “Significant changes in percent body fat over 10 months were observed in both the 400 (-2.9%) and 600 (-4.4%) kcal/session groups. Percent fat was unchanged in the control group (-0.6%). The reductions in body weight observed in both exercise groups were a result of decreased fat mass and preservation or increase in fat-free mass.”[4] Wait did I read that right? The group that did more aerobic exercise actually lost body weight and fat?  What’s going on here?  Why aren’t these cardio kings and queens getting fat?  Because exercising (no matter what type) doesn’t make you fat. And if you believe otherwise, then you may as well get into the business of unicorn breeding.guys-unicorns-mating_design

Are you bored yet? Does science have a way of beating the crap out of dogma? Anyone who claims that ‘cardio makes you fat’ has more hot air than the Hindenburg.

Here are a few more bite-sized bullets for you to remember:

  • A 10-week aerobic exercise program results in a small decrease in energy intake and an associated decrease in percentage of body fat in obese adolescents.[5]
  • Twelve weeks of regular aerobic exercise led to significant reductions in body weight, body fat percentage, and body mass index in the obese.[6]
  • Aerobic exercise training can reduce % body fat and enhance vascular compliance in obese male adolescents.[7]
  • “Aerobic training is the optimal mode of exercise for reducing fat mass and body mass, while a program including resistance training is needed for increasing lean mass in middle-aged, overweight/obese individuals.”[8]
  • In obese adolescent boys, both aerobic and weight-training exercises for a 3-month period resulted in a loss of total and visceral fat.[9]

What happens to athletes who train for years? This is where the story gets interesting. It should be as clear as the majestic blue water of the Caribbean that in untrained, fat, and/or average individuals, doing consistent aerobic exercise leads to a drop in body fat. The fact that I’m typing that sentence shows how silly the fitness industry has become. Perhaps in my next article, I’ll attempt to convince you that water is wet. But apparently some need convincing. Anyhow, there are several very cool studies on athletes. Do they get fat with all that aerobic exercise?

Check out my friend Arlene Semeco (left) with Dara Torres.  All that cardio (swimming) sure is making them fat, huh?

Check out my friend Arlene Semeco (left) with Dara Torres. All that swimming sure is making them fat, huh?

Steve Fleck PhD did a descriptive study back in 1983 showing the physical characteristics of elite American athletes.[10] (See Table 1) If cardio truly made you fat, then for chrissakes why are marathon runners so lean? I know I know. Genetics. Are they lean because they run?  Or do they run because they are lean? Or both? You might look at swimmers and say ‘hey, their body fat percentage tends to be higher than other elite athletes.’ And you’re correct. It has to do in part with thermoregulation (water is colder than ambient air temp), the buoyancy of fat (it floats), etc.  But to say ‘swimming makes you fat’ would make about as much sense as telling an Irishman to lay off the pint, feckin eh.’ You’ll notice that sports that are very anaerobic as well as highly aerobic in nature have athletes that demonstrate single digit body fat levels. Sports in which your body weight is supported tend to have higher body fat levels. So if your tutorial on science was from internet experts and the ‘science for dummies’ book, then you might conclude that having your body weight supported makes you fat. Watch. Some dipshit will post that as an internet meme.

Table 1. Body Composition of the Elite American Athletes[10]

Sport % Fat Male % Fat Female
Average College 15 25
Canoe/Kayak 13.0 22.2
Swimming 12.4 19.5
Boxing 6.9 n/a
Wrestling 7.9 n/a
Sprinters (100, 200, 400 m) 6.5 13.7
Marathon (26.2 miles) 6.4 n/a

A 1997 study from former QB Tim Tebow’s alma mater did a 20-year follow-up of track and field athletes.[11]  Six of these athletes ran the 800m, 17 did the 1500m distance or longer, and two were race walkers.  Athletes were divided into the follow three groups: high (remained elite), moderate (still performed frequent moderate to rigorous endurance training) and last but not least, low (greatly reduced training). So using the ‘cardio makes you fat’ logic, would not those who trained the most (i.e. high) exhibit the highest levels of fat?  See the answer in Table 2.

Table 2. 20-Year Follow Up of Track and Field Athletes

Athletic Level Baseline % Fat 20-years Later – % Fat
Low 15.7 21.8
Moderate 13.2 17.7
High 10.2 15.3

As you can see (and if you can’t, you need eyeglasses), those who train the most, have the lowest amount of fat.  This applies even as they age.  If anything, it should be clear that getting old results in higher body fat levels.  Yes.  In the battle of aging versus you doing everything right (i.e. exercise regularly and eating well), aging ALWAYS wins.

Distance Runners versus Bobsledders – In a classic comparison of endurance versus power athletes, Marti and Howald investigated the alterations in their physical characteristics over a 15-year period from 1973 to 1988.[12]  First let’s do a direct comparison of runners and bobsledders. (Table 3)Bob sledders

Table 3. 15-Year Follow-Up of Runners and Bobsledders


% Fat in 1973 % Fat in 1988


8.0 12.5


20.1 22.1

You’ll notice that runners are leaner than bobsledders at all time points. Wait a sec. I thought cardio makes you fat? Interestingly, bobsledders are quintessential power athletes. Shouldn’t they be leaner than distance runners? Now let’s just look at the distance runners and divide them into highly active (ran >90 km/wk), active (30-65 km/wk) and former runners (less than 30 km/wk).  (Table 4)

Table 4. 15-Year Follow-Up of Distance Runners Grouped By Distance Run/Week


% Fat in 1973 % Fat in 1988
Highly Active 9.0 5.1
Active 6.5 8.6
Former 10.3 21.2

Suzy Favor could run! We wrote a book about training and nutrition for distance running many moons ago. Check it out. It’s called “Fast Track.”

Well whaddya know.  Distance running (in general) keeps you pretty lean. Those who kept running (and did the most mileage per week) were the leanest. Those who did the least amount of that dreaded cardio, got fatter.[12]  In fact, triathletes that perform more aerobic training actually have lower % body fat levels than those who do less.[13] Why that is surprising to anyone baffles me. It’s like being surprised that kangaroos jump, eagles fly and Venezuela runs out of toilet paper.

Cardio and Muscle Mass – On the flip side, too much cardio may promote a loss of lean body mass.  But that’s NOT the same as saying ‘cardio makes you fat.’ Sometimes I feel like folks who post dopey stuff on social media need a class in ‘how to ask the right question.’  One particular study showed that in young women, doing aerobic exercise for 12 weeks promoted a loss of body weight, % body fat and BMI. But it also resulted in a loss of lean body mass.[14] On the other hand, aerobic exercise attenuated the loss of muscle mass during calorie restriction in adults with fat bellies.  Folks that dieted only lost fat and lean body mass.[15] So if you want to argue that aerobic training might result in a loss of muscle mass, you’ll have scientific support.  But it certainly isn’t universal.  Some might lose lean body mass, others not so.  Heck, some might actually gain lean body mass if they are initially very untrained.

Side Bar – Fasted versus Fed CardioIn an elegant study by Shoenfeld et al., they investigated changes in fat mass and fat-free mass following four weeks of volume-equated fasted versus fed aerobic exercise in young women on a lower calorie diet. Training consisted of 1 hour of steady-state aerobic exercise performed 3 days per week. Holy smokes!  Dr. Brad is going to make these girls fat.  How did he ever get this through the IRB and Human Subjects Review? What did they discover? Both groups showed a significant loss of weight and fat mass from baseline; however, there were no significant between-group differences. All that cardio made them fat said no scientist ever.

The moral of the story:

Pooks running

My pet dachshund “Pooks” hates cardio; she loves to sprint. But not as much as she loves to eat ground beef.

  • First of all, anyone who tells you that exercise x, y, and z (you fill in the blank) makes you fat, has about as much science training as my pet Dachshund.
  • We have a plethora longitudinal training studies as well as cross-sectional data which clearly show that performing cardio helps you lose body fat.
  • The preponderance of scientific evidence clearly demonstrates that aerobic or ‘cardio’ training results in a loss of fat.
  • If you prefer anecdotes as your ‘evidence,’ then I’d suggest you get your training/nutrition advice from Jenny McCarthy or the Food Babe.
  • If your goal is to lose body fat and look purrrty, why on god’s earth would you eliminate one form of exercise (i.e. aerobic exercise or ‘cardio’) entirely?
  • If your goal is to compete in an endurance event, then clearly you must do cardio.
  • If you’re a strength-power athlete (e.g. discus, shot put, Olympic weight lifter, powerlifter, high jump etc), you shouldn’t do any cardio.
  • If you like doing cardio, do it.
  • If you hate doing cardio, don’t do it.
  • But don’t be a fool and repeat the ‘cardio makes you fat’ mantra.
  • Getting fat is affected more by your kitchen habits than what you do in the gym/outdoors.
  • Goals determine strategies. Know your goal.

Take home message: Apples won’t rise, Pigs won’t fly, and Aerobic exercise won’t make you fat.applenewton1

Read This All You Cardio Haters

1.            Williams, L.D. and A.R. Morton, Changes in selected cardiorespiratory responses to exercise and in body composition following a 12-week aerobic dance programme. J Sports Sci, 1986. 4(3): p. 189-99.

2.            Shimamoto, H., et al., Low impact aerobic dance as a useful exercise mode for reducing body mass in mildly obese middle-aged women. Appl Human Sci, 1998. 17(3): p. 109-14.

3.            Regaieg, S., et al., The effects of an exercise training program on body composition and aerobic capacity parameters in Tunisian obese children. Indian J Endocrinol Metab, 2013. 17(6): p. 1040-5.

4.            Donnelly, J.E., et al., Aerobic exercise alone results in clinically significant weight loss for men and women: midwest exercise trial 2. Obesity (Silver Spring), 2013. 21(3): p. E219-28.

5.            Thivel, D., et al., Is energy intake altered by a 10-week aerobic exercise intervention in obese adolescents? Physiol Behav, 2014. 135: p. 130-4.

6.            Lee, S.S., et al., The Effects of 12 Weeks Regular Aerobic Exercise on Brain-derived Neurotrophic Factor and Inflammatory Factors in Juvenile Obesity and Type 2 Diabetes Mellitus. J Phys Ther Sci, 2014. 26(8): p. 1199-204.

7.            Song, J.K., et al., Effects of 12 weeks of aerobic exercise on body composition and vascular compliance in obese boys. J Sports Med Phys Fitness, 2012. 52(5): p. 522-9.

8.            Willis, L.H., et al., Effects of aerobic and/or resistance training on body mass and fat mass in overweight or obese adults. J Appl Physiol (1985), 2012. 113(12): p. 1831-7.

9.            Lee, S., et al., Effects of aerobic versus resistance exercise without caloric restriction on abdominal fat, intrahepatic lipid, and insulin sensitivity in obese adolescent boys: a randomized, controlled trial. Diabetes, 2012. 61(11): p. 2787-95.

10.          Fleck, S.J., Body composition of elite American athletes. Am J Sports Med, 1983. 11(6): p. 398-403.

11.          Pollock, M.L., et al., Twenty-year follow-up of aerobic power and body composition of older track athletes. J Appl Physiol (1985), 1997. 82(5): p. 1508-16.

12.          Marti, B. and H. Howald, Long-term effects of physical training on aerobic capacity: controlled study of former elite athletes. J Appl Physiol (1985), 1990. 69(4): p. 1451-9.

13.          Knechtle, B., et al., A comparison of anthropometric and training characteristics of Ironman triathletes and Triple Iron ultra-triathletes. J Sports Sci, 2011. 29(13): p. 1373-80.

14.          Kostrzewa-Nowak, D., et al., Effect of 12-week-long aerobic training programme on body composition, aerobic capacity, complete blood count and blood lipid profile among young women. Biochem Med (Zagreb), 2015. 25(1): p. 103-13.

15.          Yoshimura, E., et al., Aerobic exercise attenuates the loss of skeletal muscle during energy restriction in adults with visceral adiposity. Obes Facts, 2014. 7(1): p. 26-35.

BIO – Jose Antonio PhD wishes he could run but he’s slower than a sloth on Xanax. He wishes he could swim but he looks like a drunk bulldog flappin’ in the water. Instead he Paddling race SUP Clermont March 2015paddles. The beach, sunshine, and a good sweat – you can’t beat that. :-)  If you want to buy me a beer or donate money to support my sushi habit, meet me in Austin Texas June 11-13, 2015 at the ISSN Conference and Expo.