Can walking make you fat??

Haven't read the study but what I feel they are looking at it calories burned during the period of exercise.

A lot of people trust the calories burned number on the treadmill or whatever piece of cardio equipment they are using without realizing this value is based on avgs.  Now if you were a heart monitor that has advanced calories computation or one of the devices designed to track calories burned throughout the day it uses your heart rate as part of the formula in calories burned.  Faster your heart rate the more calories you burn for a specific period of time, the slower your heart rate the fewer the calories.  So walking at a slower pace that really places no additional axygen requirements on your system will not cause that much of an increase in your heart rate where as the brisk pace will which will increase your heart rate and burn more calories.

Now for Obese people the rules do change for a bit.  The sheer fact that it requires more energy to move 300 pounds than it does 200 pounds means that any exercise will be of benefit but as you lose weight so does the effort and energy expended by your body to perform this movement.  So the less you weigh and the more fit you are the more effort is needed to result in the same burn, this effort can be in Time, Distance or Intensity.

Regardless I believe that exercise is something that we should all incorporate early in this journey to make sure that it isn't a round trip.