Written by Dan Gwartney, MD
09 April 2007
Steroid-using bodybuilders have developed drug lore over the years detailing which steroids are best for certain needs. It's commonly accepted that the harsher, more androgenic steroids are best suited for "bulking up" or "massing" cycles, whereas the less androgenic steroids are used for "cutting" or pre-competition cycles.

Among the most commonly abused anabolic-androgenic steroids (AAS) is nandrolone decanoate, well known by the brand name, Deca-Durabolin. Deca, as it is called in the gym, is an ester of 19-nortestosterone, rather than being an ester of testosterone.1 19-nortestosterone is a chemically modified variant of testosterone, and as a slightly different molecule, it has different effects in the body.
 
5-alpha reductase is the enzyme responsible for converting testosterone into its more androgenic metabolite, dihydrotestosterone (DHT). An excess of DHT has been implicated in some of the side effects of many steroids, including hair loss, prostate enlargement and aggression. 19-nortestosterone interacts with the enzyme 5-alpha reductase, but rather than becoming a more androgenic steroid, it becomes less androgenic.2,3  Thus, 19-nortestosterone is protected from becoming highly androgenic and there would be a lower risk of certain side effects.

19-nortestosterone can still be subjected to other enzymes, including aromatase,4 the enzyme responsible for converting testosterone into an estrogenic hormone, which causes feminizing side effects. While these side effects are not as severe with 19-nortestosterone, as compared to testosterone, they can still lead to problematic symptoms, including gynecomastia (bitch tit).

The profile of 19-nortestosterone, with lower androgenic properties and decreased estrogenic properties, makes it a suitable AAS for use in cycles designed to increase muscle mass moderately, with little to no water retention or fat gain. Thus, many steroid-abusing athletes use Deca to enhance their appearance, attempting to create a more muscular and leaner physique.
As Deca is generally considered a less risky alternative to testosterone esters and oral AAS, it has been used in a number of different therapeutic trials, including weight loss due to AIDS,5 cancer or lung problems;6 male contraception;7 and bone loss in post-menopausal women.8

Body Composition
Recently, a study was published that investigated body composition changes in bodybuilders using a moderate dose of Deca. This paper confirmed that, in conjunction with a resistance-training program, Deca increased lean body mass. However, it was also found that while total body fat and the body fat percentage did not change, body fat was decreased in the legs and trunk.
One important finding reported in this paper was that the change in body fat was not detected by using skin-fold techniques. Instead, a more advanced technique called DEXA revealed the fat loss in the legs and trunk. DEXA is a type of body scan using x-rays, which can determine the fat mass of the body or specific regions of the body, the bone mass and the lean body mass. These findings would suggest that moderate use of Deca can increase muscle mass without causing any fat gain, improving the degree of muscularity in an individual.

Can the results of this study be considered conclusive? No, a single study is not sufficient evidence for any argument. However, previous studies have looked at the effect of Deca on body measurements in athletes10,11 with supportive results, though conflicting data has been presented in yet another study.12 Upon review, the study demonstrating no effect may have been hampered by the study design. Of the three studies showing positive effects of Deca on body composition, the dose and duration of use were similar, providing 200 milligrams of Deca per week for at least six weeks. The study showing no effect used a lesser dose of 100 milligrams of Deca per week for a   period of just three weeks. Thus, it appears there is a dose-related effect in that at least 200 milligrams per week for a period of no fewer than six weeks would be required.

It can be reasonably stated that the use of Deca in moderate doses can improve the body composition of most people. However, what has not been fully determined is how this occurs and what risks may be involved in the use of Deca.

Muscle: More Mass, Less Damage
19-nortestosterone is a more anabolic steroid, compared to testosterone and other AAS. The long ester chain, which is responsible for the slow release of Deca, also gives it a more anabolic effect.13 The anabolic nature of Deca is responsible for the gains seen in muscle mass. As muscle mass increases, there is an associated increase in the metabolic rate, as muscle is an active tissue. Thus, additional calories are burned throughout the day.
In addition to an increase in muscle, there is evidence from animal studies that Deca may also improve exercise tolerance,14 allowing people to remain active longer, particularly in vigorous activities such as running or weight training. It stands to reason that for many people, a greater amount of exercise each week will lead to a greater number of calories burned, supporting fat loss.

The study also reported a decrease in muscle damage following exercise, which is important for maintaining or building muscle mass. Deca seems to support an increase in muscle protein synthesis (anabolic effect) as well as decreasing muscle damage and breakdown due to physical stress (an anti-catabolic effect). These findings are in agreement with the experiences of most bodybuilders who have used Deca; workouts may last longer or be more frequent with less of a risk of overtraining, resulting in sustained muscle growth.  

There are other effects of Deca that may support body composition changes in athletes and non-athletes alike. In a study of normal men,15 it was reported that 300 milligrams of Deca per week improved glucose tolerance. An improved glucose tolerance is meaningful,as it suggests that the body more efficiently uses sugars, burning them as fuel, rather than storing the sugar, which may predispose one to obesity. This effect was not seen in the same group when testosterone enanthate was used, suggesting that there is a Deca-specific effect. The authors felt that it was the non-aromatizable (though 19-nortestosterone has been shown to be aromatizable4) nature of Deca that was responsible for the improved sugar metabolism. This improvement was felt to be independent of the insulin, which may suggest a role for Deca in diabetics, or at least type II diabetics.

The effects of Deca may be psychological as well as physical. Again, referring to an animal study, it has been reported that Deca use may cause changes in the brain that would be similar to those seen in other drug addictions.16  These changes may create a "reward" effect from Deca use, which may decrease other destructive behaviors, such as binge eating, or may support efforts to control diet and continue an exercise program.

    Not Without Consequence
Deca seems like a reasonable therapy for improving body composition, as it aids in increasing muscle mass, while possibly decreasing total body fat. Deca use is not without consequence. First and foremost, Deca is a controlled substance and the sale or possession of Deca outside of indicated uses, is a felony crime. Deca has caused temporary infertility;7 indeed, it is being investigated as a possible contraceptive. Abuse of Deca could lead to prolonged or even permanent reproductive damage, though there are medical interventions that might restore reproductive function. This is an important issue for anyone considering family planning. All steroids may cause changes in liver function, blood lipid and cholesterol levels or clotting of the blood. Many consider these changes inconsequential, but sudden death has been reported in steroid-abusing athletes.17

In summary then, as has been demonstrated in these studies, Deca may provide significant benefits in improving the body composition of athletes and bodybuilders, including increased muscle mass and decreased body fat. While the anabolic function of Deca is well defined, other effects need to be considered, including improved exercise tolerance, anti-catabolic protection and psychological reward, reinforcing the behaviors necessary to develop the body composition changes. Deca use is not without risk, as it is a felony crime to sell or possess Deca and several health risks have been associated with its use, including sudden death. The use of Deca in frail populations is becoming accepted as HIV-related wasting and aging changes are being corrected with the use of AAS, including Deca. The positive results seen in most populations, including male athletes, are seen with fairly moderate doses of 200 to 300 milligram-per-week cycles providing measurable benefit.

References  
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