Can I carry over uneaten calories?

The answer is yes, and it's definitely better to 'save' them in advance rather than spending calories with the intention of paying them back, and then it not happening! Use the Week View to keep an eye on how you're doing across the week – as long as your 'under' days off-set the 'over' days you'll still be on track to lose weight. Just ensure your average intake across the week is not falling below 1,200 calories per day, as this is the absolute minimum we would recommend.