The “obesity epidemic” came upon us suddenly. It began roughly 1978, rapidly accelerated until 1997, then leveled off. When it began, about 32% of the population was overweight, another 13% were obese, and a scant 1% were extremely obese. When it ended, 34% were overweight (roughly the same as when the epidemic began), but the percentage of obese individuals skyrocketed to 31%, while the extremely obese saw a five-fold increase to 5%.
And then it stabilized, but at the higher percentages. Despite all the public health programs, the focus on nutritional information, the waxing and waning of dozens of diets, the percentages have remained stubbornly the same, with a slight drifting upwards.
The consequences of the “new normal” have been catastrophic. Healthcare costs related to obesity now top $190 billion, over 20% of the annual medical spending in the U.S. It contributes to the leading causes of death— diabetes, heart disease, stroke, and some cancers. It reduces quality of life, limits mobility, exacerbates conditions such as arthritis and depression.
So what caused it? The abrupt shift upward in all overweight categories, combined with an equally-abrupt levelling off, suggests an external force of some sort rather than a genetic cause that would manifest over a much longer timeframe. What happened in the late 70s to catapult a sizeable portion of the population into an unhealthy range?
And why did it level off? The increase from 1978 to 1997 was a relatively straight line, climbing inexorably upward until in 1997 the acceleration stopped; the graph again twitched horizontally and has remained more-or-less level since.
And most importantly, why has it not reversed itself? With all of the focus on healthier habits, exercise, proper nutrition, medical intervention— why have we not reverted to our former slender selves?
There are a few likely candidates for culpability, plausible singly or in combination. The next few posts will examine some of them.