A Review into Exercise Fat Loss Methods

There are numerous advantages to fat loss for an athlete. In weight categorised sports such as boxing and MMA, a reduction in body fat would mean that an athlete may be able to compete at a lower weight, and by removing this excess weight from fat stores may increase power by reducing the load the muscles have to move therefore increasing speed. This means by reducing fat levels and preserving the levels of fat free mass the athlete is both more powerful and competing in a weight class which is advantageous.

For an example, take two boxers in the middleweight division, the weight limit for a middleweight fighter is 72.57kg (160lbs). If both fighters are on the weight limit, but one fighter has 12% bodyfat and the other has 7% bodyfat, the fighters are still the same weight however the second fighter may have an advantage by having more metabolically active tissue, possibly giving power and strength advantages over the fighter who is carrying more fat.

In team sports, such as football, having a lower bodyfat percentage means that the athletes are not carrying excess weight which may by detrimental to endurance and performance. Reducing the weight whilst maintaining fat free mass means the athlete becomes more powerful, faster and their performance increases.

Certain sports may be aesthetically based, such as figure skating and gymnastics. These sports are less about performance and more about the visual aspect of the body and as such, the demand to have a low level of body fat is almost paramount.

There are several different categories of exercise which may aid a reduction in bodyfat levels, however it is important to understand that reducing bodyfat without an adequate diet conducive to fat loss will result in little, if any, change in levels of bodyfat.

The aims of this review is purely based around the effects of exercise on aiding fat reduction. A well planned diet should always be followed to ensure fat loss is possible, however the diet should not only provide an adequate calorific deficit to reduce bodyfat but also maintain sufficient energy and nutrients for performance. Other considerations such as whether to perform exercise after food or when the body is in a depleted state also need to be addressed.

The most widely used methods in exercise for fat loss can be categorised as Sub-maximal Intensity, High Intensity and Resistance training.

Sub-maximal Intensity: When most people think of fat loss and weight loss they inevitably think of long sessions of prolonged exercise, i.e. running, swimming, cycling. This is normally performed at a steady 60-70% VO2 Max for prolonged periods. This training is performed at an intensity which is proven to use a higher proportion of energy from fat stores. As a major part of fat loss is energy expenditure, or more accurately expending more energy than is taken in, long periods of sub-maximal exercise not only significantly increase energy expenditure but also increase the proportion of the energy which comes from fat.

Maximal Intensity: Although maximal intensity is predominantly anaerobic, and mainly uses glycolysis and the phospho-creatine systems to provide energy during maximal intensity exercise such as sprinting, hill sprints, short cycle sprints and as such does not burn as mainly calories during the actual exercise itself, it has been shown to raise the body’s BMR. BMR is an abbreviation of ‘basal metabolic rate’. Broken down into simple terms, the body’s BMR is a measurement which is taken after sleeping for 8hrs and fasted for 12 and calculates the amount of energy the body burns in a 24hr period if it were to do nothing other than complete rest. BMR is similar to ‘resting metabolic rate’ which is slightly less accurate. Increasing the BMR of an athlete is advantageous in a fat loss situation as it links back to the main principle of fat loss which is, Burn more energy than is consumed. The substrate to fuel the raise in BMR is predominately fat, leading to greater fat oxidation and loss at rest.

In a study published in 1994 by Tremblay et al, subjects were placed into a group which would perform an endurance based exercise protocol and the second group followed a maximal intensity exercise program. Although the mean energy cost for the endurance group was more than double the energy cost of the maximal group (120.4 MJ compared to 57.9 MJ), the maximal intensity group showed a decrease  in skinfold measures nine-fold greater than in the endurance group. This decrease in fat levels may be down to an increased BMR induced by the maximal intensity.

Resistance Training: Like maximal intensity training, resistance training does not show a large energy cost and fat use during the exercise but what it does show is raised energy costs following the exercise. This is highlighted in a study published in Medicine & Science in Sports & Exercise by Lemmer et al. (2001). In the study, subjects followed a 24wk strength/resistance training program. The results showed a significant increase in the RMR of 7%. Another benefit of resistance training is that it increases the amount of fat free mass which again leads to a higher energy demand as muscle is metabolically active whereas fat is not.

Combinations: Combining the previous categories into one training routine may be able to select the benefits from each one without the drawbacks. For example, sub-maximal exercise followed by resistance or vice versa may offer more benefit than doing either exercise alone. Research into this was carried out in 2005 by The Journal Of Strength and Conditioning Research. The study compared, resistance only, run only, resistance-run, and run-resistance and measured the excess postexercise oxygen consumption (EPOC) which may highlight the impact that the exercise has on energy expenditure. The studies results showed that run-resistance had the greatest increase in EPOC levels. The study suggested that post exercise energy expenditure would show the greatest increase following a run-resistance protocol.

In conclusion, all the aforementioned categories of exercise type will aid fat loss, however each of the different methods have something to offer. Increasing the amount of calories which are burned through exercise is likely to be achieved by including sub-maximal exercise such as jogging or cycling into a routine. Increasing the calories and fat which is burned at rest can be achieved by adding either maximal-intensity exercise such as sprints or resistance training into a routine. Resistance training may stimulate an increase in fat free mass, again, helping burn more fat at rest.

References :

Journal of Strength & Conditioning Research. (2005). Aerobic and Resistance Exercise Sequence Affects Excess Postexercise Oxygen Consumption. Journal of Strength & Conditioning Research. 19(2).

Lemmer, Jeffrey T.; Ivey, Frederick M.; Ryan, Alice S.; Martel, Greg F.; Hurlbut, Diane E.; Metter, Jeffrey E.; Fozard, James L.; Fleg, Jerome L.; Hurley, & Ben F. (2001). Effect of strength training on resting metabolic rate and physical activity: age and gender comparisons. Med. Sci. Sports Exerc., 33(4), 532-541.

Tremblay, A., Simoneau, J.A., & Bouchard, C. (1994). Impact of exercise intensity on body fatness and skeletal muscle metabolism. Metabolism, 43(7), 814-818.