Rather than 30-60 minute sessions on the bike instead get a tabata timer and set it to have you sprint on the bike for about 22 seconds and rest for 1.5 - 2 minutes in between for 8 reps. The total time for this will be a little over 15 minutes. Work up to doing this 2x a week. You'll sprint all out for 22 seconds, then pedal slowly for the rest period. The days you aren't doing the sprints, walk or ride the bike moderately. Have bananas or potatoes or something on the day you do the sprints. Also consider switching to a lower fat, higher protein version of your diet, at least on the days you do the sprints. On the days you aren't sprinting, consider one of them being a day of fasting.
Female, 5'3", 49, Starting weight: 163lbs. Current weight: 135 (more or less).
Starting squat: 45lbs. Current squat: 160 x 2