[nradov]

The major federal government food assistance programs came out of findings in WW2 that many potential recruits were literally malnourished and underweight. They had grown up poor and starving during the Great Depression. Beyond the human tragedy this was a national security issue. Some men were too small and weak to meet military standards.

[bradarner]

Indeed. Which would seem to indicate that positive growth along the Kardashev scale will lead to hypertrophy not atrophy, as conjectured by the OP. One could hypothesize that growing control of energy is highly correlated with the ability to empower a population to increase in muscle mass. Of course, history would seem to indicate that there can also be a correlation to increased obesity.

[kiba]

Doubtful that the energy spent on building muscles is significant as there are also compensating factors that stabilize our metabolic expenditure.