All anabolic steroids have a tendency to reduce HDL (good) cholesterol and increase LDL (bad) cholesterol. The relative impact of an anabolic/androgenic steroid on serum lipids is dependant on the dose, route of administration (oral vs. injectable) type of steroid (aromatizable or non-aromatizable) and level of resistance to hepatic metabolism. With regards to nandrolone at a dose of 600mg per week over 10 weeks demonstrated 26% reduction in HDL cholesterol levels. This suppression is slightly greater than an equal dose of testosterone over an equal period. In other words it shows a slightly more negative impact on HDL/LDL ratio with nandrolone than with testosterone cypionate. It’s always recommended to accompany the use of this product with a low saturated fat diet and a cardiovascular exercise program.
It should be noted that in theory if one was to consistently suppress your natural estrogen levels for a long period of time, this would negatively impact your health, including your cholesterol. Due to the ability of Letrozole- to inhibit estrogen so much, this should definitely be a concern to most users. However the research that has focused on the relationship between use of letrozole and cholesterol levels is rather inconsistent in it's findings. Many studies have concluded that the compound is detrimental to both a user's HDL and LDL cholesterol levels, while other research has found no link. Obviously individuals are best served to monitor their cholesterol while using any compound via blood tests however barring that, letrozole should simply not be run for extended periods of time if at all possible. Doing so could cause serious medical complications.
Along with the issues related to blood lipids is the fact that many users complain that their libido is dramatically reduced when using the compound. This is related to the fact that estrogen is partly responsible for the regulation of an individual's sex drive. Since Letrozole- is so potent it can often drive estrogen levels too low and this inhibits a user's libido. To avoid this users can lower dosages, but some anecdotally report that even extremely low doses of the drug can cause problems. If this is the case a less potent compound such as exemestane or anastrozole may be a more appropriate option.