I could be wrong but my interpretation is .........
I think biologically you have to consume something like 3,000 calories over and above the energy you use to put on 1lb in weight. The new size bars are about 40 calories more than the old, so after eating 75 of them (75 days worth if you have one a day) your weight loss will be 1lb less than it would be compared to the old style bars. So I guess it's not strictly true that the new bars won't affect weight loss at all, but in the grand scheme of things a one pound difference over a 75 day period isn't significant enough to worry about. Hope this makes some sense.