Although I am usually not inclined to posit speculations on why a particular drug does or doesn't do something, in this case I will. Im guessing that the higher doses of Anadrol cause enough appetite suppression (at least anecdotally) to make eating rather difficult. It can also increase insulin resistance and glucose intolerance (5). This has the effect of making macronutrient absorption more inefficient, and could also be a factor in reducing gains when the dosage goes over 100mgs/day. Unfortunately, Anadrol also has a reasonably profound effect on your body's natural hormonal system, on par with most other oral steroids , but not as bad as most injectables, and its certainly not as harsh on your lipid profile as many anabolics are
The dosage used is important in determining the level of benefit received. Anabolic steroids tend to be most efficient at promoting muscle gains when taken at a moderately above therapeutic dosage level. Below this (therapeutic), potential anabolic benefits are often counterbalanced, at least to some extent, by the suppression of endogenous testosterone. At very high doses, smaller incremental gains are noticed. In the case of testosterone enanthate or cypionate, for example, a dosage of 100 mg per week is considered therapeutic, and is generally insufficient for noticing strong anabolic benefits. When the dosage is in the 300-600 mg per week range, however, the drug is highly efficient at supporting muscle growth. Above this range, a greater level of muscle gain may be noticed, but the amount will be small in comparison to the dosage increase. Below are some commonly used dosages for the steroids listed earlier. Avoid taking the higher end of the dosage range during your first couple of cycles. You will have excellent results from lower dosages during your first few cycles. Lower dosages are also less likely to cause excessive side-effects and give you the opportunity to learn how your body reacts to steroid usage.