I just did a search for "Catholic weight loss blog" and came across a couple nice ones. Here are some reviews.
Mary's Nest is a lovely blog by a woman in Texas. She's really had it with the starvation dieting that passes as acceptable these days. She's getting her spiritual life in order with some friends and writes about it.
Take Back Your Temple is a Christian weight loss blog. Some interesting ideas. So far I've only read a few articles, but I liked what I read. This one is about how a woman made a breakthrough in her weight loss when she learned to budget money. I also read "Fruit for food, Leaves for medicine." That article quotes the scriptures for ancient advice on nutrition. I'm definitely going to read this blog.
The Light Weigh is a program of Catholic weight loss. The main crux of this is that people are obese for emotional reasons. I'm really not sold on this concept. while I think that there are emotional reasons why people eat, I'm more convinced that the high caloric density of the foods we eat are much more to blame than our psyches. It's mentioned on a lot of Catholic weight loss blogs, so I thought I'd mention it here. I'm skeptical about this one.