Lipitor is a medication used to lower cholesterol levels in the blood. It is a type of drug called a statin, which works by blocking the production of cholesterol in the liver [1]. According to the sources provided, there are no known exceptions to taking Lipitor with low-fat substitutes.

One of the sources [2] explains that taking Lipitor with food does not affect its effectiveness. However, it is recommended to take it at the same time every day, with or without food. It is also important to avoid consuming grapefruit or grapefruit juice while taking Lipitor, as it can increase the risk of side effects.

The other source [3] discusses the benefits of a low-fat diet in conjunction with taking statins like Lipitor. The study found that a low-fat diet can improve the effectiveness of statins in lowering cholesterol levels, particularly in individuals with high levels of triglycerides. However, the study did not mention any exceptions to taking Lipitor with low-fat substitutes.

In summary, there are no known exceptions to taking Lipitor with low-fat substitutes. It is important to take Lipitor at the same time every day, with or without food, and to avoid consuming grapefruit or grapefruit juice while taking the medication. A low-fat diet can also improve the effectiveness of Lipitor in lowering cholesterol levels, particularly in individuals with high levels of triglycerides.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1312230/
[3] https://www.ahajournals.org/doi/full/10.1161/CIRCRESAHA.118.312782