I don't know why most diets suggest it, but I choose low fat cottage cheese because I think there is a signifcant difference in taste and texture over the fat free version. However, there isn't must difference in taste and texture between full fat and lowfat. Also, I find the bit of fat makes the final product much more filling (in addition to the protein cottage cheese provides).
On the labels that I've checked, the calories are about the same between no fat and low fat cottage cheese. But NF frequently has food starch added, which increases the carb content. I buy Light and Lively, which is 1% fat and doesn't have added food starch.
Wow, Meg, that is interesting to know! I buy NF because there is a brand I like just as well as the LF... but I sure don't want added food starch so I think I will go look on the carton!!
I think that sometimes the fat content can alter other nutrient content as well. Sometimes lower fat foods (especially dairy) will have lower amounts of calcium, protein, and other vitamins and minerals as a result of the fat deduction. I am sure it depends on the brand though...