Perhaps a silly exercise question

So, I have a question that will seem rather silly.  But, here it goes:

Does your body ever start to require more exercise than it is used to in order to lose weight? 

Let me explain where this is coming from:

I had surgery on 20 December.  On 28 December, I started walking.  The first day, I walked one mile.   Each day, I walked just a little bit further.  Today, I am up to 6 miles.  It takes me 2 hours to complete 6 miles, and I really do not have more time to dedicate to my exercise regimen.  I am afraid that in order to continue to get the benefits of exercise, I have to keep upping my distance.  So, my question is more like, is exercise like a drug, that you need to keep increasing the dosage in order to get the buzz, and therefore the 'benefit' or can you maintain a certain level and maintain the weight loss.  I have presently lost 83 pounds, and feel great. 

Even as I type this, it sounds crazy.  But, I do know that the exercise has played a huge part in my weight loss.  I just don't want to jeopardize my progress, and at the same time, I don't want my whole life to be consumed with exercise.

Thanks!

In a word yes.  As you lose weight you burn less calories doing the same exercise.  Remember back when walking into the grocery store felt like exercise.  As you lose weight your body requires more exercise to burn the same 500 calories as it did before you lost weight.

Here's a suggestion rather than adding more and more time to your walk,  why not increase your intensity.  You can do this in different ways (if you have a treadmill)...increase the incline, the speed, you could even add leg weights.  You also have to start adding strength training.  Building muscle is the number one way to burn fat and calories.  You can also exercise with DVDs...people swear by Zumba or something like that.   

What I did to continue to lose weight was, increase my exercise was.... instead of walking I started intervals.  I will walk for 4 minutes and run for 3 minutes.  As I need to I increase my run time and decrease the walk time.  You can start as low as you want...5 minutes of walking, 30 seconds of running.  I guarantee that you won't have to do that whole 2 hours and you will burn more calories.  This technique has helped me blow through my plateaus.  I do 90 minutes of exercise.  60 minutes of that is cardio, I never go beyond 60 minutes.  I just increase my run time.  Then I do 30 minutes of weight lifting.  This works for me.   

I think you need to increase your intensity. For example:

It currently takes you an hour to walk 3 miles. Why not try to complete 3 miles in 55 minutes. Each week, set a goal to take 2-3 minutes off your 3 mile walks.

Soon your walk will turn into a very fast walk, then a jog, then a run., then who knows... 2 hours is a lot to dedicate to your fitness, so kudos, I just thing you could get a much more dramatic result if you up your intensity.

I understand where your question is coming from as I was in exactly the same spot.  I started using a HR monitor in December.  I found that at the same intensity, same exercise time (5 miles in 90 minutes), my HR was not getting up there and I was not burning as many calories.  My personal trainer said that it was two-fold:  my heart/lungs are stronger (more efficient) and my body is lighter and that it is time for me to up the intensity, not the length of time.  So last week I started the C25K program and I complete it during my 5 mile walk.  Now my heart rate is jacked up again, I am burning more calories, but am completing my 5 miles in less time.  It won't be long at all that I will be slogging (slow jog) the 5 miles.  I also added a spin class between my walk days and work out with weights now.

time to pick up your intensity, not add time to your walk.  Good Luck!

When you do the same exercise over and over, your muscles get used to that exercise and don't burn the same amount of calories.  This is what a lot of exercise videos are based on, they try and work different muscle groups every 30 to 60 seconds.  If you like to walk, on a rainy or snowy day, you should try Leslie Sansone.  She has walking videos that allow your body to move in different directions, using many different muscle groups.
I work out anywhere from 1 to 3 hours a day, but I mix it up.

Monday:  Body Toning, muscle building, swimming
Tuesday:  Tae Bo with Billy Blanks and Zumba
Wednesday:  Cardio and swimming
Thursday:  I play the Wii
Friday:  Body toning and muscle building
Saturday:  Free day - Get to choose whatever I want to do
Sunday:  Wii (My fitness coach) and Zumba

Building muscle is key to taking weight off and keeping it off.  The more muscle you build, the more calories you burn...just by sitting around!  Big muscle groups:  Your upper legs, your but, and your stomach.

I would look at ExerciseTV.TV...they have many free work outs you can watch streaming on your computer.  I have tried a few and they are pretty good.

Hope this helps!