I'm unconvinced this is a good or accurate app... I really just use it to log whatever the scales say as it's simpler than me maintaining a spreadsheet and it makes a nice graph.
That number is from the last 7 days average only. The trend analysis in the app is a bit crappy.
823kcal/day * 7days = 5761kcal/week
3500 kcal in a lb of fat
5761kcal/week / 3500kcal/lb * 0.454g/lb =~ 750g/week
(Caveat: Obviously this doesn't take into account any changes in BMR or increased exercise regimes.)