I've walked pretty much all through my weight loss and also a couple years of maintenance. I tried running, and physically... nope, can't do it. Too high impact for me.
The biggest thing for the calorie burn, is distance covered in the amount of time you do it (either walk or run). And yes, you can cover more distance in the same amount of time, if you run instead of walk. But since running is out for me, I walk including hills and often strap on a weighted backpack, to increase the intensity a bit. This isn't a casual stroll either. I walk as though I was late to a movie I really wanted to see. It's not a jog but it's a pretty good clip.
So no it's not necessary to run, to either lose weight or be fit. Weight loss is more about what/how much you're eating anyway.
Ruth in Cookeville, TN Central Time Zone
Promise me you'll always remember: You're braver than you believe, and stronger than you seem, and smarter than you think - Christopher Robin to Pooh
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