Basically to lose weight you should consume less calories than you burn in a day but you first have to figure out what you burn in a day.
calories burned equal to calories consumed = maintain weight
calories burned less than calories consumed = gain weight
calories burned more than calories consumed = loss of weight
Do a search for a calorie burn calculator to help you figure that out. A good site will help you calculate calories burned (approximate) based on your weight. It will count by activity, I.E. sleeping 8hrs, walking hrs per day, sitting, washing dishes, etc. Once you enter all of the day's activities you will end up with what you burn in 1 day. I weight 145lbs. so I burn in a typical work day about 1700-2000 calories per day. If you ride say 1hr at 20mph. That's about 750 calories burned. (remember these are all estimates) So in a typical work day with excerise I will burn 2450-2750 calories. for this day, I would probably want to consume about 1,800 calories. Good food though, not junk.
The 500/day rule is very general. I believe 1lb equal about 3,500 calories.
This approach is mathematical so if you burn a little more than you eat, you should lose weight a little at a time. You don't want to lose to fast anyways.
Ultimatley once you get to know your body, you'll figure out what you should consume depending a your day's activites.
John Budnik said:
Short of going to some lab, how do you determine how many calories you need to consume in a day. I've gone to numerous "expert" resources and they give me numbers that diverge from each other by hundreds of calories. Then the "experts" go on to say that you should lose weight by limiting your calories by 500/day. How do you do that when the numbers they give are possibly off by that many calories? Are there any definitive answers to this?