Along the lines of this question on activity and weight loss, there was a study published in 2016, that essentially found that the body will self adjust, to keep calorie expenditure relatively stable regardless of the amount of physical activity. This was done across a moderate sized cohort (330+ people) across several locales.
As seen by the above graph, the common assumption is that "other" (BMR, etc) is one set, and as you increase physical activity, Total Energy Expenditure (TDEE or TEE) just grows.
What the study found, is that the body will self adjust, and lower the daily cost (by fidgeting less, resting more, etc) so that the total expenditure plateaus. If correct, this would explain the plateau effect on weight loss, as muscle builds to reflect current activity. By extension, that means that only by actually changing the physical requirements of the body (muscle burns more than fat to maintain) can we achieve a sustainable fat loss.
So as health professionals, should we be turning more towards weightlifting as a primary activity to physically change the metabolic requirements of the body?
Related studies for further reading: