If you do that commute 2-3 days a week the pounds will start flying off. Your one day round trip is also more than my 5 day commute. But I have gotten so into biking over 3 years of bike commuting that I now supplement by adding 15-20 miles to my morning commute a couple of days a week and doing another 40-60 miles on the weekends.
Like others said, start slow and don't get discouraged