Just switching to low-fat foods is not likely to yield much health benefit in most women. Rather than trying to eat 'low-fat,' women should focus on reducing saturated fats and trans fats.
This shows that you can't rely on using low-fat substitutes to make a difference. You really need to think about what kinds of fats you're eating and the foods that should be part of your diet, such as vegetables, for instance.
You may be able to get enough calcium and Vitamin D through the foods you eat.