Metabolism in US Is Declining

Americans today have significantly lower metabolic rates than their ancestors did,
despite similar calorie consumption. In the 1940s Minnesota Starvation Experiment, lean men maintained their weight on 3,500 calories per day with moderate activity, while modern calculators suggest they should need only 2,000 to 2,400 calories
Research by Dr. John Speakman shows that basal metabolic rate (BMR) has declined
significantly over time, while Active Energy Expenditure (intentional exercise) has actually increased, contradicting the common belief that we simply move less than our ancestors
Currently, approximately 73% of American adults are either overweight (30.7%) or obese (42.4%). This is a major public health crisis that cannot be explained by reduced physical activity alone
The dramatic increase in polyunsaturated fatty acid (PUFA) consumption since 1909 (up 238%) has likely contributed to decreased metabolic rates, as these fats can
downregulate metabolism compared to the saturated fats our ancestors consumed
Average body temperatures in the United States have been steadily declining since the Industrial Revolution, providing additional evidence of decreasing metabolic rates across the population