1 hour walk on the treadmill

I did a one hour walk on the treadmill for 3.69 miles today.  My joints were bothering me because I haven't been eating very good.  I don't know how I can work so hard exercising then ruin it by eating the wrong food and way to much of them.  Weight is starting to creep up again so I need to get my act together before it's back to the 250's again.  Set backs happen and I need to get it together