Losing weight from job?

I have worked in a warehouse job for 3 months and have lost 30 pounds. I weighed 215 before this job and I now weigh 185. I eat about the same as before I started the job. Throughout the day I start out by getting rid of trash. This involves bending over a lot for cardboard. I also walk a lot to clean the warehouse. Later in the day we unload trucks of furniture with a dolly. Many of these pieces weigh 100 pounds and more. Is it all the movement I do at this job the reason I lost this weight? I never was very physically active before this. It could be someting like getting diabetes but I bet it is from doing my job. Any thoughts?