The 8 Biggest Fitness Myths and Misconceptions

by Jason Karp |   Date Released : 12 Oct 2011
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Jason Karp

About the author: Jason Karp

Jason Karp, PhD, is the 2011 IDEA Personal Trainer of the Year, 2014 recipient of the President’s Council on Fitness, Sports & Nutrition Community Leadership award, and creator of the REVO2LUTION RUNNING™ certification. He has more than 400 published articles in international running, coaching, and fitness magazines, is the author of eight books, including 14-Minute Metabolic Workouts and Run Your Fat Off, and speaks at fitness conferences and coaching clinics around the world.

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Comments (8)

Karp, Jason | 16 Jan 2014, 21:06 PM

In reference to the resting metabolic rate myth, while it has become popular among fitness professionals to say that you must weight train to build muscle to increase your resting metabolic rate (RMR) and subsequently lose weight, this point is highly exaggerated and not supported by scientific research. Using one MET (3.5 ml/kg/min) as RMR, each pound of fat-free mass is calculated to burn 11.5 calories per day, a negligible amount since it takes a 3,500-calorie deficit between caloric consumption and expenditure to lose just one pound. Research has also documented this calorie-burning potential of fat-free mass. Even as far back as 1971, Holliday calculated that RMR in children and adolescents was equal to eight calories per pound of wet muscle per day.

While there is a positive relationship between fat-free weight and RMR among animals and humans with large differences in body weight, whether an individual can significantly increase his or her RMR is questionable. Although some studies have shown that RMR (or total daily caloric expenditure) increases in response to strength training, many other studies have shown that it does not. Some of these studies have been done on older people, whose RMR is more likely to be influenced by exercise training given the age-associated loss in muscle mass (sarcopenia) and the associated loss in muscles’ metabolic activity. RMR is not significantly different between people of different aerobic fitness levels and is independent of training status.

Even more to the point is that people lose weight only when they are in negative energy balance (i.e., caloric expenditure is greater than caloric intake). Research has shown that when people are in negative energy balance and losing weight, RMR actually decreases. Research has shown that RMR decreases during weight loss even when muscle mass is maintained by weight training. Since no research has shown that RMR is maintained much less increased when people are in negative energy balance, fitness professionals cannot say that weight training increases RMR that results in weight loss.

For fat loss, the effects of training are not about how much muscle you add to your body but rather about how you enhance the metabolic profile of the muscles, since it is the change in composition of the metabolically active portions of muscles that accounts for any change in RMR. For example, endurance training enhances fat oxidation by increasing skeletal muscle mitochondrial content and cellular respiratory capacity. Weight training (or long, intense endurance training), provided it depletes muscle glycogen, helps repartition post-exercise food intake, so ingested carbohydrates are used to replenish muscle glycogen stores rather than be stored as fat. Depleting muscles of glycogen (and then not consuming carbohydrates after your workout) threatens the muscles’ survival since carbohydrates are the preferred fuel for muscles. In response to this threat, muscles “learn” how to use fat more effectively. With the right training stimulus, over time muscles become better fat-burning machines.

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Bowden, Andrea | 16 Jan 2014, 20:09 PM

I'm so confused. I 'm pretty sure Alwyn Cosgrove told me in The Hierarchy of Fat Loss that we can raise our RMR by gaining muscle. (Other articles- by reputable trainers also have told me so) Or did I mis understand?

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Koehler, Jessica | 29 Oct 2011, 14:25 PM

I really enjoyed, this article - great thought process and approach. However, I need to make a comment in relation to point #5 to clarify and give my opinion (not going to go as far as citing research due to lack of time) from a different perspective other than weight-loss or fat-burning. From a safety and function standpoint: strength training requires an optimal level of neuromuscular efficiency and physical energy, especially when complex or highly integrated movement patterns are being performed with a load or performance-related tempo. On the whole, If an individual chooses to perform aerobic exercise prior to strength training (especially if they are a novice exerciser or someone who thrives on high-intensity training), the increased neuromuscular and muscular fatigue level will only place them at a higher risk of injury #1 - due to incapacity or reduced capacity to hold proper form and correct exercise technique and #2 - developing poor movement patterns due muscular compensations from consistent fatigue. I would beg to argue this point even if the strength training doesn't include additional loads and/or performance related tempos, especially in relation to novice exercisers. From this standpoint (taking the metabolic variable out of the equation), there is a very important reason to perform strength exercises before aerobic exercise. From the metabolic standpoint, there is also much research in relation to females/hormones/exercise-mode sequencing, which I believe should be addressed with #5 as well. Thanks for the article, I enjoyed reading.

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Sinitiere, Nick | 27 Oct 2011, 18:45 PM

Jason, I truly appreciate you responding. I completely understand calling metabolic rise from exercise 'artificial', that's a nice way of putting it, and I'll give you credit whenever I use it. The title to point #1 was metabolism and how exercise effects it, not necessarily weight loss. Although your points about weight loss and its relation to metabolic rate (caloric input/output) and high/low carb diet are in my humble understanding correct, I respectfully disagree that we are 'more similar than different'. Of course we will all be similar in the sense that we are all on the "homo' branch of our grand family tree, thus all run similar 'programming functions' that are driven deeply into our Nervous System. But how then do you reconcile the fact that for example, Eskimo and South American Indian natives have completely opposite diets, yet both share for all practical purposes 'perfect' health? (Nutrition and Physical Degeneration -Dr. Weston Price & Biochemical Individuality- Dr. Roger Williams) I'm speaking to actual 'health' not so much 'weight loss'. By your logic we are all identical. calorie input/output is a Natural process by which ALL life forms either gain or loss mass.

Various homeostatic control systems of the body dictate 'health'. Scientific fact. ALL processes involved in 'life' as we know and define it, strive for homeostasis. Even various modalities in Nature that we may not consider 'alive'. Health is a measure of efficiency at a cellular level, thus lack of disease processes at the cellular level. For example: pepsin, among other digestive enzymes have HUGE variation in pH from person to person. Many times up to 500%. My point is, the same food eaten by two people, may take opposite processes to regulate. If my resting digestive pH is a '4', and yours is a '7', a food with a pH of '6' will require polar opposite responses from these two individuals. All in all, I think you're on point, but again in my humble opinion, I don't think you or the mainstream "Nutritional Community" takes into account adequately enough the variability of people globally. I definitely learned a bit from this exchange, I appreciate your willingness to elaborate and defend your claims. Not that you need it by any means, but you've got my respect. Any further comments you have would be appreciated as well.

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Karp, Jason | 27 Oct 2011, 17:45 PM

Hi Nick. Even if someone worked out every day, the rise in metabolic rate would be artificial due to the workouts alone, not to a change in the resting metabolic rate, which defines the amount of energy (or number of calories) needed to live. As far as metabolic typing, we are actually more similar to one another than we are different. While some people may be more sensitive to certain foods than others, calories still must be expended for weight loss. Low -carb diets have been shown to be effective for weight loss in the short-term, but that type of diet is not sustainable and so is not effective in the long-term. As far as the circadian rhythm, I'm not aware of any research that shows that the time of day that people eat influences how much weight they gain or lose. If you've done a hard workout at 5 pm and have severely lowered your glycogen stores, the carbs that you eat at dinner at 8 pm will be used to restore your glycogen because that is a metabolic priority. So even if you've eaten before going to bed, there are still priorities that must be met.

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Karp, Jason | 26 Oct 2011, 17:42 PM

While some research has shown there is an increase in resting metabolic rate following a strength training program, the increase really is relatively small compared to what is needed for weight loss. While 30-142 calories a day may seem like a lot when it's extrapolated over a year's time, the calories are so easy to get right back with just a little amount of food or drink. One glass of milk has over 100 calories. So, it could potentially impact weight as long as the person does not replace the calories through his/her diet, which is very difficult to not do.

Jason Karp

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Diedrich, Paul | 26 Oct 2011, 13:06 PM

I enjoyed reading this article. It's about time someone clarified these myths that many trainers have historically beleived. Althought I'm not nearly as technical as Nick, I am confused on one thing and hopefully you can clarify this for me (Myth #1). Unless I read this wrong, you mention that resting metabolism is not affected from strength training. But then it states that some research has shown relatively small increases between (30-142 kcals/day). This may not be much on a daily basis, but in the grand scheme of things, couldn't this be signficant? On an annual basis this adds up to 3 to 14 lbs/year. Imagine throughout a lifetime. Thanks again for writing this fantastic article, I will be sharing it with my colleagues.

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Sinitiere, Nick | 13 Oct 2011, 14:04 PM

Excellent article, Jason. These are some "wives tales" that our industry needs to finally purge, these being among them. However, I had a few specific thoughts while reading this. I respectfully disagree with one claim you made. This was alluded to at the point you make mention of low-card diets, and that some research supports and some doesn't. That fact alone speaks to biochemical individuality of the Human race. Metabolic Typing is the only system that accounts for this individuality, is it not? I've seen not one other system /school of thought that is as logical, but more importantly, as scientifically sound for determining food prescription. All that to say, I was a bit surprised to hear a PHD not make mention of this. As far as metabolic rate goes, follow me down this rabbit hole if you will: We know metabolism is spiked up to 48, and sometimes 72+ hours post-workout. What if an individual works out consistently once every 3 days? or every other day? Would this not be defined as a true change of metaboilc rate, that is regulated by activity and not necessarily biochemical process? A clear definition of terms is lacking here. A final thought about Circadian Rhythm...again a logical rabbithole, I'll spare the science due to time constraint. Circadian Rhythm effects hormones and biochemistry. Food assimilation/digestion/elimination is effected by hormones and biochemistry. Is it not logical (there is a scientific basis to this, also) to conclude then, that what we eat does indeed effect us differently depending on when we eat it? It is a known fact that the time of day effects performance via the hormonal mechanism. Why would that not apply to digestion/metabolism/elimination/etc. as well? Again, great article, any additional thoughts you have would be appreciated. I'm a sponge....feed me.

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