The Fat-Burning Zone; the myth that finally died.

neurosomatic By neurosomatic, 24th May 2014 | Follow this author | RSS Feed
Posted in Wikinut>Health>Exercise & Fitness

Skeletal muscle has a hierarchy of fuel choice when at various levels of activity. However, the currency of energy remains the calorie. This page discusses how a biochemical fact was misrepresented and resulted in disappointing results from exercise for millions over decades

Aerobic Nation

For years we heard it- stay inside your aerobic zone that is the only way you will burn fat and so we faithfully kept it at low intensity and most of us, if we lost any weight at all, lost it only when we moved abruptly from being sedentary to starting a program (let’s come back to that later). Then came, P90x; challenging all of the dogma, saying the exact opposite and producing results. This was followed by a slew of such programs including insanity, cross fit, Tap out fitness, interval training, tabata even famous, women-work out “the firm” adjusted their work outs to include high intensity intervals. With the advent of famous proponents of intensity such as Jillian Michaels and Bob Harper, the myth of the importance of the aerobic zone for weight loss and fitness had been finally obliterated; after all you can’t argue with results!

The Science Behind the Myth

But why did the myth persist for so long and was it based on actual science? Let’s take the second question first- it was based on Science, the problem is that from a single fact came inaccurate assumptions and deductions. Fact: using fatty acids as a substrate for energy absolutely does require oxygen (through a process called beta oxidation) as opposed to glucose which can be burned sans oxygen (through glycolysis) leading to the formation of lactic acid. This was the basis of the argument that purported that we needed to stay in our aerobic zone(at maximal availability of oxygen) to burn fat: if we were gasping for breath like the suckers on the insanity DVD’s it meant we were in oxygen debt and therefore minimizing the burning of fatty acids. We were instead burning glucose and making lactic acid. An important question that we did not ask was: so what? Was burning a fat calorie somehow superior to burning a glucose calorie? After all, on the dietary side we were told a calorie is a calorie – more or less. Whether it is from fat, protein, starch or sugar, it was a unit of energy. Judging by the results post shattering of myth, it is the anaerobic zone that is superior for weight loss. This is also supported by the fact that people do lose weight initially on their aerobic programs. Think about it: if you’re at a low level of fitness and start working out, you are more likely to spend a large part of the time in the anaerobic zone for a given set of exercises. The same exercise that makes you gasp for breath within a few weeks becomes easy and you stay happily at that level, proud of yourself that you are no longer inelegantly red in the face and gasping and wheezing for breath but missing the fact that that was the period in which you were losing weight.

Public Health Outreach and the Myth

This brings us to another silent partner in keeping this myth alive despite its poor showing on the results side: the public health PR. “Walking is the best exercise.” From a public health stand point , yes it is. It’s less taxing on the joints and the heart and therefore less likely to result in injury and heart-related events. In addition, walking produces wide spectrum benefits even crossing over into mental wellness. However, unless it requires effort from you, on an individual basis, it is very limited both in its ability to get you past a certain level of fitness and result in weight loss.

Tags

Aerobic, Cross-Fit, Fat-Burning Zone, High Intensity

Meet the author

author avatar neurosomatic
A self-styled philosopher with academic training in the biomedical sciences. I'm that scientist that acknowledges that the anecdotal might be true even if there is no published data.

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Comments

author avatar Sivaramakrishnan A
25th May 2014 (#)

It is all confusing to the layman. What is stated as a fact is soon disproved. I feel a balanced approach to diet and exercise makes sense - siva

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author avatar neurosomatic
25th May 2014 (#)

Thanks for your comment! I would say it is the studies on diet that have led to more confusion than those on exercise, this is unfortunate. However, I think this is happening less and less. When it comes to exercise, I would say this is the only one where the recommended approach has been changing. As for balance and moderation, while there is power in an intuitive sense of what that is, some knowledge is required to know what constitutes a balance.

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author avatar Emma
14th Jun 2014 (#)

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