I attribute this change to two things. First, I went from a very sedative lifestyle to a semi-active one. Going from working out never in a week to 2 or 3 times a week makes a big difference. The second thing is watching what I eat. I've cut my breakfast and lunch portions nearly in half, while eating a healthier dinner. (Sometimes.)
I was not perfect this week, and I will dare to say that I probably never will be. But it is encouraging to see those kind of numbers after just one week.