"Despite the best of intentions and massive educational programs of national and federal health agencies to counsel Americans to eat a healthy diet, the proportion of overweight and obese Americans is steadily increasing. Several interesting hypotheses are being pursued...pertaining to how diet and lifestyle changes have combined in modern cultures... to increased risk for cardiovascular disease and diabetes...

"One hypothesis is that during much of our evolution we experienced periodic, often unpredictable, cycles of feast and famine but now live in a state of constant 'feasting.' According to this concept, individuals with a 'thrifty' 'genetic makeup] are more efficient ...in conversion of calories to fat tissue during times of feasting, and this would have had a survival benefit in long periods of repeated food shortages during development of our species...'So] we see that, until relatively recent times, the human condition was characterized by periodic episodes of feasting and famine...and 'was] strongly influenced by moderate to intensive physical activity. Industrialization in the late 19th and 20th centuries has led to a marked reduction in physical activity levels for most people. In most developed countries, physical activity is now generally relegated to a part-time leisure activity rather than a steady daily activity found in the workplace...'Also,] since the early 1950s the fast-food industry has provided easy access to calories, making them very affordable and 'supersized' them..." Emphases added.

From:The Journal of Nutrition, vol. 133, 2003. By: Wargovich & Cunningham, U. of S. Carolina School of Med. & Dept. of Epidemiology & Biostat., U. of S. Carolina & S. Caro. Cancer Center, Columbia, SC 29208.