Aerobic Exercise Fails at Fat Loss

Aerobic exercise is one of the worst ways to burn fat. Most people will find this statement shocking. After all, the fitness experts have been telling us for decades that aerobic exercise is the only way to reach optimal body composition. They are wrong. If you are serious about fat loss, you should seriously rethink your exercise program. Replacing an aerobic regime, with one focused on anaerobic cardiovascular exercise is the surest way to increase fat consumption during exercise and rest.

The fact that aerobic exercise is not optimal for fat loss has much evidence to support it. It can be confirmed through real world evidence, practical experience, and science. Science is often thought of as the only criteria necessary for proof, but it
frequently provides only mixed messages. Although it has taken time, science is now proving other forms of exercise superior to aerobics when it comes to fat loss.

Cardiovascular vs. Aerobic Exercise

Aerobic exercise and cardiovascular training are not the same thing. Cardiovascular exercise refers to the heart and vessels of the body working at an accelerated rate to sustain physical activity. Aerobic exercise simply means the use of
oxygen to burn fuel for energy. This distinction is important because aerobic exercise is limited. In other words, once oxygen becomes depleted, you are no longer doing aerobic activity. Cardiovascular exercise is maintained as long as the muscles
of the body are working, but aerobic exercise must be done at a low enough intensity to ensure an adequate and continuous oxygen supply. That is the problem. In order for the body to get leaner (i.e., burn fat and build muscle), it must be
continually challenged with increasing intensity. Aerobic exercise has a built-in intensity ceiling and therefore becomes a limiting factor for adaptation and fat loss.

Proponents of aerobic exercise will quickly point out that more fat is burned with aerobic exercise than with anaerobic exercise. This is only true from a relative perspective¬. Lower intensity exercise uses a higher proportion of fat compared to
sugar. However, exercise done at higher intensity and beyond the aerobic training zone burns more total energy and fat.

EPOC and Extended Energy Usage

The truth is aerobic cardiovascular exercise does NOT burn more total fat than higher intensity cardiovascular exercise. But that’s not the only reason anaerobic exercise is superior for fat loss. The last twenty years in exercise research has shown
it is not just what happens during exercise, but also what happens after that makes a difference. Have you ever walked up a large flight of stairs or done a hundred yard dash? Have you ever noticed what that type of activity does to your breathing? It
is not until you reach the top of the stairs or the end of the sprint that your body really begins to gasp for air. This phenomenon is known as EPOC (Excess Post exercise Oxygen Consumption) or oxygen debt. It refers to the “catch up effect” the body has in response to intense exercise. After near maximum exertion, the body suffers from a relative debt in
the amount of oxygen it used compared to the amount it was able to breathe in. After intense exertion is over, the body is forced to increase respiration to recover its loses. This is a mini-example of what occurs in anaerobic cardiovascular training. Researchers have shown this effect stimulates metabolic changes that cause the body to burn fat and calories at an accelerated rate for an extended period of time even after the workout is over. This increased metabolism induced by intense cardiovascular exercise can last as long as 48 hours!! (19) The same effect cannot be achieved with “aerobic zone”
training.

EPOC in Evolutionary Context:
The EPOC phenomenon is not yet fully understood. However, using a historical frame of reference and known science allows some idea of what is happening. When early humans went out to hunt or had to avoid becoming dinner themselves, their level of fitness was the number one determinant of success or failure. Every time they failed to catch dinner or barely escaped danger, their bodies were forced to adapt by getting more lean and fit. This was a natural evolutionary response to the harsh realities of their natural world. Hormones released from intense activity were what stimulated this growth. Every
time a person eats, exercises, or sleeps hormones are released that act as chemical messengers. These molecules send signals telling the body how to manage its fat stores, whether to build muscle or burn it, and how to adjust metabolic
activity. When it comes to exercise there is a threshold of intensity that must be breached in order for extended metabolic fat burning to take place. Part of this adaptation is the EPOC phenomenon. Aerobic exercise is not able to generate the
intensity required to produce this beneficial effect so the body never receives the signals to burn fat and build muscle.

Hormones and Intense exercise:

People have been confused with the hormonal fat burning effect behind EPOC. If we remember that the net action of a single hormone depends on other hormones around with it, we get a better understanding than looking at a hormone’s
action in isolation. Cortisol, for instance, has been blamed for causing fat storage at the belly. However, this negative effect only surfaces if human growth hormone, testosterone and other growth hormones are not present at the same time.

One of cortisol’s actions is to raise blood sugar. If activity does not use up this liberated fuel, insulin is needed to lower blood sugar. Unfortunately, insulin lowers blood sugar by storing it as fat and then locking it in the fat cell. As long as insulin
is around, fat burning cannot take place. When cortisol raises blood sugar it is doing so as a natural protective mechanism. The body’s natural response to stress is the release of adrenaline and cortisol so that we have high-energy sugar to fight
or flee. If this release of sugar is not followed by exercise or exercise at too low an intensity, large amounts of cortisol, adrenaline, and sugar are still released, but never used. Lack of intense movement means unused sugar gets stored as
fat while unoppossed cortisol, adrenaline, and other stress hormones do damage to our physiology. This actually makes us more susceptible to fat storage and accelerates the aging process.

Stress hormones are designed to work together with growth hormones like testosterone and HGH. If cortisol is not accompanied by its growth-producing counterparts it will cause muscle wasting and fat storage around the waist. However,
when testosterone and HGH are present with cortisol, fat storing at the tummy is blocked and the three hormones together amplify fat burning. This scenario results in fat loss, not fat gain. Stress hormones in high amounts are appropriate when
they act together with growth hormones. Interestingly enough, this is exactly how early man’s hormonal system worked in the world of actual fight or flight. By focusing on higher intensity cardiovascular exercise we can literally program our bodies
to burn fat not only during exercise, but at rest. Aerobic exercise never allows the body to reach the intensity required to release growth promoting testosterone and HGH and continually exposes the body to unopposed cortisol, which makes fat
loss more difficult.

Stress hormones do not lead to fat gain when they are coupled with high intensity activity. In the natural world, stress leads to increased availability of sugar, which leads to the ability to fight or flee. High intensity activity works with this process by
generating protective fat burning hormones that make us leaner and stronger. Low intensity activity, like walking or jogging, is unable to duplicate this effect.

It is useful to point out that early humans did low intensity activity all day everyday. To a prehistoric caveman walking was considered a necessity not exercise. Modern humans should do as much of it as they can, but the last thing one needs to
do in response to high levels of stress and blood sugar is engage in “slow-mo” aerobic exercise. This runs counter to our inherited physiology and biochemical understanding. Our genes and metabolic processes are tuned to the lifestyle of our
hunter-gather ancestors. Intelligent exercise works along with this ancient physiology.

The Science:

In case you’re still skeptical, here is some science? A 2001 study in the journal, Medicine and Science in Sports and Exercise looked at low intensity aerobics verse high intensity exercise. One group in the study exercised using standard “aerobic zone” training while the other group used intense interval exercise (alternating extremely high levels of exertion with less intense bouts). The interval group exercised for 2 minutes at a highly intense 97% max heart rate. They then rested by doing three minutes of low intensity activity. The “aerobic zone” group did moderately intense activity at close to
70% of max heart rate. Each group burned exactly 300 calories during their exercise session. Despite exercising for longer, the aerobic group lost less body fat at the end of the study compared to the interval group. Fitness in the interval group was
also significantly greater than the aerobic group. This study demonstrates the effect of EPOC and shows that exercising for fat loss is more than just counting calories.

Another study published in the same journal in 1996 showed that intense exercise burned more fat than traditional aerobics. In this study, the interval group burned more fat during exercise, but they also exhibited increased fat burning
effects that persisted for 24 hours after the exercise had ended. These results show that anaerobic activity burns more overall fat and calories during exercise, and leads to continued fat burning after exercise as well. The most compelling
thing about this study is that the interval group was able to accomplish this with a workout that was a full 15 minutes shorter than the “aerobic zone” group.

The most telling study on the effects of anaerobic versuses aerobic cardiovascular training came in 1994 in the journal Metabolism. The researchers wanted to see how intense interval exercise compared to traditional aerobics in terms of
body fat and metabolism. The results showed that the aerobic group actually burned 48% more calories than the interval group (120.4 MJ vs 57.9MJ) over the course of the study. By the caloric and aerobic models we would predict this meant
they had better results, but they did not. Despite the huge caloric disadvantage, the interval group enjoyed a 9 fold greater loss in subcutaneous fat (fat under the skin). The interesting thing about this study was the measurement of a fat burning
enzyme in both groups. Resting levels of 3-hydroxyacyl coenzyme A dehydrogenase (HADH), an enzymatic marker of fat burning, was significantly elevated in the interval group but not the aerobic group. The impact of this study is staggering
when you consider the interval group trained 5 weeks less than the aerobic group, had shorter workouts, but far exceeded the aerobic group in fat burning at rest and during exercise. The measurement of fat burning enzymes in this study shows
that anaerobic cardiovascular training can actually “teach” the body to be a more efficient fat burning machine. (3)

Aerobic exercise is not all bad. While it does have marginal benefit in attaining fat loss, it lives up to its reputation in terms of helping the bodies keep the fat off. It is also a healthy and beneficial form of activity, and of course any form of exercise is
better than none. Walking and lower intensity exercise should be done as often as possible. They benefit the body, the mind, the spirit and are energizing. Just remember, if you want to lose fat and truly transform your body you will have to
invest in high intensity exercise. Learning new exercise strategies that deliver true results is the best approach to optimal body composition. A sole focus on aerobic training only serves to make a difficult process more challenging.

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Jade A. Teta ND, CSCS & Keoni Teta ND, LAc, CSCS
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