Fat Loss Fallacies

Introduction

Out of all the athletes, trainers, and fitness enthusiasts that I’ve met in my life, I can count on one hand the number I have met who didn’t care about fat loss at one time or another.  It is, almost without a doubt, the main driving force behind the increased interest in exercise the world has seen in the last few decades.  Unfortunately, just like any market where the pie is large, there are plenty of people who scam and spread misinformation in an effort to get their piece.  I hope to cut through the BS and point out some commonly perpetuated fallacies on this topic.


Spot Reduction
The pervasiveness of this idea makes me want to put a screwdriver into my eye socket.  You may have also heard people refer to this as “toning.”  I think the reason people seem to hold on to this notion so dearly is because it is very appealing.   Quite simply, a localized, targeted loss of fat on the body is a physiological impossibility.  Fatty acids are mobilized into the bloodstream all throughout the body (5).  Intramuscular fat stores may be the exception to this rule (2), but oxidation of intramuscular fat does virtually nothing to enhance aesthetics.

One of the origins of this myth may be the burning sensation experienced when fatiguing a particular muscle.  This burning sensation is not representative of the amount of fat being oxidized for energy by the muscle, but of the state of acidosis the muscle is entering because of metabolic demand (5).

The exact mechanisms of exactly how much and where we lose fat are not fully understood.  The best suggestion I have found is the relationship to a certain class of adrenergic receptor on the surface of fat cells.  Cell receptors let them respond to signals from elsewhere in the body.  A higher receptor density makes the fat cell respond to adrenal hormones more readily (Most notably adrenaline), and thus more likely to release the energy stored within (3).  Therefore, the theory goes that you will preferentially lose fat from cells with a higher adrenergic receptor density and hold on to fat in cells with a lower adrenergic receptor density.   Sadly, you have absolutely no control over the receptor makeup of your fat cells.


Fat Burning Heart Rate Zone
This myth doesn’t infuriate me like spot reduction, but I still classify it as conventional gym wisdom.  The idea is that you burn a higher proportion of fat if you maintain your heart rate within a specified range.  Actually, this is 100% true.  Once you surpass the lactate threshold, your start relying a lot less on aerobic metabolism to meet energy demands (1).  However, the idea that this maximizes fat loss over the long term is misguided.  By that logic, it would be ideal to sit motionless all day long, as a resting state requires a higher relative proportion of fat oxidation to meet energy needs compared to any exercised state.

The bottom line is that creating a caloric deficit is still the most important factor influencing fat loss (1).  You expend the most calories by working as hard as you can within a given period of time.  The best thing you can do to promote increased usage of fat as an energy substrate is perform frequent bouts of vigorous cardiovascular exercise.  It has been shown that increased levels of aerobic fitness are positively correlated with increased usage of fat as the preferred energy substrate (5).  With that said, this still isn't necessarily the most effective way to actually change body composition.  Furthermore, as your fitness level increases, the “fat burning zone” will actually shift to higher intensities.  That is, individuals that have better cardiovascular fitness primarily power exercise via aerobic means at increasing intensity levels compared to untrained individuals (5).


High Reps
Frequently when trying to lose body fat, trainees will alter their resistance training programs such that intensity drops dramatically and volume goes up.  The idea is that high repetitions sets will better promote fat loss.  This is only half true.

One of the reasons for the change in training parameters reconnects with the idea of spot reduction or muscle toning.  People think this type of training promotes such a physiological phenomenon to take place which, as I’ve already explained, just doesn’t happen in our bodies.  If anything, total exclusion of moderate to heavy lifting for your resistance training program is a terrible idea.  When aiming for fat loss and operating in a caloric deficit, it becomes very important to keep lifting at an intensity sufficient to support muscle hypertrophy.  The hypertrophy stimulus makes muscle loss less likely.  At least some moderate to high intensity lifting should be a part of any fat loss program.  The more trained the individual, the higher the intensity should be.  This is the result of an increased minimal intensity threshold one must meet with increased training age (4).

With that said, some level of high repetition training has its place.   The truth is higher repetition sets result in a greater volume of work performed within the same time epriod.  This means more calories will be burned.  As well, there is a greater cardiovascular demand, potentially resulting in a greater “afterburn” effect post-workout because of elevated oxygen consumption, or EPOC (5).  So, doing some higher repetition work is fine and dandy.  The problem is when it’s done at the complete exclusion of heavier work, and the rationale behind it is different than most people realize.


Conclusion
There is a ton of garbage fitness information out there, especially regarding the concept of fat loss.  Always be weary of BS.  Make sure you don’t take everything at face value.  Do your own research and work hard; you will get the physique you desire.






References
(1) Baechle, T. R., Earle, R. W., & , (2008). Essentials of strength training and conditioning. (3rd ed.). Champaign, IL: Human Kinetics.

(2) Bompa, T. O., & Cornacchia, L. (1998). Serious strength training. (2nd ed.). Champaign, IL: Human Kinetics.

(3) McDonald, L. (1998). The ketogenic diet, a complete guide for the dieter and practitioner. Kearney, NE: Morris Publishing.

(4) Verkhoshansky, Y. V., & Siff, M. C. (2009). Supertraining. (6th ed.). Denver, CO: Supertraining Institute.

(5) Wilmore, J. H., Costill, D. L., & Kenney, W. L. (2008). Physiology of sport and exercise. (4th ed.). Champaign, IL: Human Kinetics.