Breakthroughs in research technology are providing new information in exercise science and sports medicine at an incredibly rapid rate. A lot of this new, exciting information has to do with fat metabolism during exercise. While this information can lead to more effective strategies that help people shed body fat, interpreting new data in its correct context can sometimes be quite difficult, even for highly trained professionals.
On occasions, new findings can appear to contradict what we already know regarding established recommendations. However, in a lot of cases, the new information isn’t placed in its correct context. Rather than providing clarity, it promotes greater misconception and confusion. If the new findings are misinterpreted and then relayed to the public, it can quickly become misinformation. This can make fat loss which is already a perplexing topic for many people, even more confusing.
Therefore, in this report, I’ll present you with the most recent research on fat metabolism and body fat reduction. More importantly, I’ll place this data in its correct context so you can apply the latest science-based information to your training with complete confidence.
Spot reduction – is it possible after all?
Spot reduction by definition is, exercising specific regions of the body to lose body fat from that area. For years, the health and fitness community told the public that it couldn’t happen; it won’t happen and will never happen. Well, guess what? A recent study has shown that it does happen! Kind of……
A rather elegant and very sophisticated study on fat metabolism has been completed and published by scientists from Denmark. This research demonstrated that active muscles use nearby fat stores as fuel during exercise.1 Technically, that’s spot reduction.
Does this mean that performing thousands of sit-ups will burn the fat off the stomach to produce six-pack abs? Based on this new information, in theory, it might. In reality, I doubt it.
We know that aerobic exercise increases whole-body lipolysis (the mobilization of fat from fat cells). The most important (relevant) finding from this excellent research is that lipolysis seems to be greater in fat cells that are adjacent to working muscle. Physiologically, this phenomenon makes a lot of sense. Working muscles require a lot of energy, particularly after exercise to fuel recovery and repair; the most abundant source in close proximity to meet this requirement is localized fat.
However, it’s important to explain the protocol that provided this data. The researchers reported this phenomenon in thigh muscles after a two-hour bout of exercise with one leg and two 30-minute bouts using the other leg (completed 30-minutes apart).
If we try to apply this info’ to our quest for “six-pack abs” it doesn’t hold up. Even if you were prepared to perform several hours each day of neck-breaking sit-ups and other abdominal exercises, by virtue of the abdominal wall’s relatively small muscle mass, only a proportionately small amount of calories will be expended. Therefore, I doubt you’ll see much of a transformation to your midsection. Besides, the research shows us there is an easier, more efficient way to get your six-pack.
“Teach” your muscles to burn more fat!
Fat is mobilized from fat cells in response to exercise so that muscles and other tissues can utilize this fuel as an energy source. That’s basically how body fat is “burnt.” The misguided age-old adage of long duration, low-intensity exercise for fat burning and body weight reduction is slowly but surely dying. Now, thanks to an ever-increasing amount of research that shows the extent of this whole-body lipolytic effect comes down to the intensity of exercise completed as well as duration.2 That means to burn fat, you’ve got to pay your dues with sweat; vigorous (relatively intense) activity for a prolonged amount of time. But you already knew that!
The problem with low-intensity exercise is that the body is a very efficient machine and quickly “learns” how to expend less energy to complete a given task.
Gentle (low-intensity) exercise doesn’t burn many (fat) calories to begin. However, when performed on a regular basis, fewer calories are expended. The bottom line is, if you rely on low-intensity exercise as your sole means of activity for fat reduction, you’re in for a life-long uphill battle with the pudge.
Recent studies confirm that trained muscles burn more fat for fuel, regardless of the exercise intensity. That means regular exercise “trains” your muscles to utilize more fat (and less carbohydrate and protein) to fuel exercise. And this appears to be the case whether the person performs aerobic exercise at moderate or high intensities.3 Therefore, a commitment to cardio exercise all year round will give you a huge advantage right from the start; it teaches your muscles to utilize a greater amount of fat for fuel.
Shorter duration, intense aerobic (cardio) exercise is defined in the laboratory as 70% or above a person’s maximal oxygen uptake. It has come to the forefront as a highly effective strategy for fat loss. Outside the lab, the term “intense” simply means that you’ve got to be puffing during your cardio activity. The term “short-duration” generally implies a time frame of 20 minutes or less. The time frame is proportional to the effort exerted. People that are new to this type of exercise merely need to focus on working “hard” continuously for 20 minutes. The easiest way to gauge this is with an intermittent check of your heart rate; it needs to be beating at 70% or above of your maximum heart rate (which is 220 minus your age).
As your fitness level improves, so does your license to push yourself. Max-OT Cardio is a standard to which I recommend you aspire to. Essentially, Max-OT Cardio is the most uncomfortable 16 minutes of your life! But don’t worry, the results you’ll see, and the feeling of accomplishment you achieve will make this type of exercise a very positive addiction in your life.
Why exercise at high-intensity even if your goal is purely fat loss?
The fundamental rule of fat loss still applies; fewer calories have to be consumed than expended on a regular basis. High-intensity exercise ensures this calorie deficit. High-intensity exercise causes greater metabolic disruption to the body’s homeostatic systems; energy production, cardiovascular, respiratory and thermoregulatory systems are all challenged. In turn, this promotes a much greater requirement for energy during and after the activity, which ensures a higher degree of lipolysis!
A study from the University of Wisconsin has helped to explain why high-intensity exercise is more effective for body fat reduction. The Wisconsin researchers showed that not only does the body expend more calories during exercise at higher intensities, the body’s metabolism (rate that it burns calories) remains elevated for longer in the hours after exercise. In comparison, low-intensity exercise, (regardless of the type) fails to elevate the metabolism to any significant degree after the activity.
Similar adaptations and better results
When compared to traditional, long duration aerobic exercise, can you really get more bang for your buck with shorter-duration, high-intensity cardio training? A recent study has shown that a high-intensity interval training program was effective at promoting the same muscle adaptations as traditional endurance training but also yielded performance results that were equal to or better than the endurance program.4
The researchers at McMaster University in Ontario, Canada compared the physiological and performance effects of short-duration, high intensity vs. traditional endurance training using sixteen men placed into one of two cycling groups. The high-intensity group performed sprint training; four to six all out maximal (30 seconds) sprints separated by four minutes of recovery. The traditional endurance training group performed continuous exercise for up to 120 minutes at an intensity of 65% of maximal aerobic capacity.
The program only lasted two weeks, and performance was assessed by pre and post training time trials and muscle adaptations; samples were taken before and after the two-week training program.
Concerning exercise performance, the high-intensity group showed an improvement of 10.1%, whereas the traditional endurance training group only improved by 7.5%. Additionally, both groups exhibited similar adaptations in muscle oxidative capacity, buffering capacity, and glycogen utilization.4
The key aspect of this research was the difference in the time commitment to the two training protocols. The high-intensity training required only 2.5 hours a week while the traditional endurance training program required 10.5 hours a week. However, the high-intensity training program yielded performance results and muscle adaptations that were equal to or better than the endurance program.4
I’m not suggesting that endurance athletes should abandon their traditional programs to focus on short-term work. This study examined the effects of only two weeks of exercise training at each end of the fitness spectrum. However, you’d have to agree that the results are extremely impressive, to say the least. This research highlights the benefits that can be achieved by short- duration, vigorous exercise. Most of us have a very limited amount of time to devote to exercise each week. If exercising intensely for 2.5 hours a week as opposed to working for 5 times that duration, provides equivalent physiological adaptations and better results regarding fat loss, you’d be crazy not to consider this approach.
The bottom line
The ability to shed body fat from exercise comes down to intensity, duration, and frequency. You need to work long enough and hard enough to challenge the body’s regulatory systems which in turn elevates the metabolism and promotes lipolysis. Regarding frequency, you must train consistently; this will teach your muscles to utilize more fat for fuel (thus sparing protein and glycogen). The more aerobically fit you become, the more you can challenge yourself with a variety of intense, short duration workouts. (Hint; employ the Max-OT approach to all types of exercise). As long as an equivalent amount of emphasis is placed on your diet, these strategies will ensure more efficient and effective reductions in body fat.
1. Am J Physiol Endocrinol Metab. 292:E394-9, 2007.
2. Strength & Conditioning Journal 28;70-71, 2006.
3. European Journal of Applied Physiology 99; 245-250, 2007.
4. Journal of Applied Physiology, 575:901-911, 2006.