hi, im a 53 yr old woman who was 192 lbs 6 weeks ago. ive been on a diet of protein shakes,fresh basa. streamed veggies,fresh fruit etc and have been eating approx 850-900 cals a day. i lost 17 lbs in the foirst 4 wks. but the last 3 weeks i gained half a lb! i still desperately want to lose 40 more lbs by the summer. why havent i continued to lose weight? i power wlk 6xs a week uphill for 60 mins also. why am i now struggling to lose more weight. thank you so much