Lipitor is a brand name for the drug atorvastatin, which is used to lower cholesterol levels in the body. According to the drug patent watch website [1], atorvastatin works by inhibiting an enzyme in the liver that produces cholesterol. It is often prescribed to individuals with high levels of low-density lipoprotein (LDL) cholesterol, also known as "bad" cholesterol.

Low-fat substitutes, such as margarine or vegetable oil spreads, are often recommended as a healthier alternative to butter for individuals looking to lower their cholesterol levels [2]. These substitutes typically contain less saturated fat than butter, which is a type of fat that can raise LDL cholesterol levels in the body.

While using low-fat substitutes may help to lower LDL cholesterol levels, it is important to note that they may not have a direct effect on the efficacy of Lipitor. According to a Harvard Health Publishing article [3], the effectiveness of statins like Lipitor is not affected by changes in diet or lifestyle. However, a healthy diet and regular exercise can help to improve overall cholesterol levels and reduce the risk of heart disease.

In summary, low-fat substitutes may be a helpful addition to a heart-healthy diet for individuals taking Lipitor to lower their cholesterol levels. However, it is important to note that these substitutes may not have a direct effect on the effectiveness of the medication.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.healthline.com/health/butter-cholesterol
[3] https://www.health.harvard.edu/newsletter_article/help-for-your-cholesterol-when-the-statins-wont-do