Absolutely true. An archaeological study was done at a site in Turkey which was an early Neolithic village. Down deep in the strata, human remains are found which show a fairly healthy population. But in the shallower strata, the skeletons show typical signs associated with agriculture:
heavy muscle-attachment marks (from heavy labor), degraded joints (same), bone deformation (malnutrition), shorter stature than the older skeletons (poor diet), "starvation rings" - periods of no bone growth (famine or lack of adequate food).
We paid a price for the Neolithic Revolution:
we got high population and civilizations as we know them, but also a near-famine existence for so many for most of recorded history.
Exactly. Our bodies are set to defend against energy LOSS. All of our enzymes, hormones, etc. are tuned for "feast or famine" rather than the constant abundance that agriculture has brought.