Hi - It seems to vary from person to person. In theory it shouldn't make any difference as there's only about 30 calories extra in a bar and that would just add 210 cals in total over a week - not enough to make a difference to weight loss. Having said that some people believe that bars slow down the weight loss and some find that they are not as filling as the shakes. I have had a bar a day (more or less) since week 3 and it hasn't affected my weight loss as far as I know. I couldn't do without them, but all to their own. Why don't you try it for a week and see how you go?