Industrilization and Urbanization   

"From 1978 to 1993, the time Americans spent in the kitchen decreased from three and a half hours to thirty minutes" [37]. 

Around the 1920s, many technological innovations replaced human labour in agriculture productivity. The invention of the tractor and other machinery, chemical fertilizers, and plant and animal breeding promised less back-breaking work [38].

Technological progress allowed the agricultural system to keep up with the loss of man-power and increasing population. Farmers were able to reduce their unit costs and expand their farm output at the same time.

As food production and processing became more specialized, work became simpler and more routine [39]. This allowed for mechanization—the replacement of human and animal labour with machinery that could aid in routine tasks [39], such as sowing seeds and harvesting [4 0]. Production became more dependent on resources manufactured off the farm, such as agricultural chemicals and fossil fuels [41]. Monocultures, for example, led to a greater dependency on synthetic fertilizers (to manage nutrients in soil) and chemical pesticides (to control crop pests) [42]; In food animal production, hormones and antibiotics were introduced to speed the growth of food animals [43]. These new technologies made production more predictable, reliable and repetitive [39].

As a result we had more food (usually with less nutrient quality) and less physical effort to produce it leading to numerous diseases.