How in that time did portion sizes change? Consumption of soda? You also have the introduction of home tv’s then computers leading to more sedentary activities at home. Along with other home appliances making cleaning easier. What was the shift from home cooked, made from scratch meals to meals eaten out or prepared by others which tend to be higher calorie per bite? What are other factors like growth hormones in meat and dairy products? What about the shift in consumption to processed soy and corn in our diets? The rise of food like products that have been engineered to keep making us want to eat. So many factors.