Modern humans have always had the belief, conscious or subconscious, that they could lead a less-than-optimal lifestyle and yet health care could prevent the ill effects.  This is particularly true thinking about medical care.  Why eat an optimal diet when the unhealthy food is so good?  Exercise is more effort than I want to put in.  Optimal weight is not that important.  Afterall, the majority of the population is overweight.

Humans are good at rationalizing but not so good, at times and with certain subjects, at being rational.  Being rational is looking at the hard statistics. U.S. life expectancy between 1950 and 2019 increased 11 years to 79 years of age.(1)  Then COVID-19 hits in 2020 and life expectancy drops to 77 years and further to 76 years in 2021.  COVID-19, drug overdoses, and accidental injury accounted for about two-thirds of the decline in life expectancy.  The other third was largely related to diseases such as heart disease, diabetes and other diseases which are highly related to lifestyle.

While the impact of COVID-19 was dramatic resulting in 1 million deaths in the U.S. and causing a decline in life expectancy, it drew attention away from a decade’s long erosion in the pace of increasing life expectancy.  Diseases such as heart disease, diabetes and others which are highly related to poor lifestyle and the resulting overweight and obesity have slowly been decreasing life expectancy gains over the past 3 decades.

A paper in the New England Journal of Medicine in 2005 stunned many in health care.(2)  The authors discussed the difference in life expectancy projections based on those from past experience and those based on disease trends.  The differences are significant.  Projections based on past experiences such as are used by Social Security do not take into account the explosive increase in lifestyle related factors such as obesity.  They simply look at what happened during the higher past periods of increased life expectancy and apply those forward; if we gained 5 years of life expectancy over the past 4 decades, we will in the next 4 decades.

The 2005 paper discussed the dramatic rise in obesity over the past 30 years and the resulting increase in related diseases like diabetes and heart disease.  The current lifetime risk of diabetes is 40%, a phenomenon highly related to overweight and obesity.  The authors’ comment on this statistic is telling, “In fact, if the negative effect of obesity on life expectancy continues to worsen, and current trends in prevalence suggest it will, then gains in health and longevity that have taken decades to achieve may be quickly reversed.”

While life expectancy has been increasing but at a declining rate over the past 30-40 years, healthy longevity defined as the period of life without chronic disease, has declined.  We have been able to keep people living a little longer but with a larger period of being diseased.

It is not just the prevalence of diabetes that is a drag on life expectancy but also the age of onset.  The median age of onset of the disease has plummeted meaning more years for complications to develop shortening life.  The incidence of type two diabetes in those 18 and under in 2002 was 9/100,000.  By 2019 this had increased to 22/100,000. 

I was struck by the comments of a diabetologist I heard speak back in the late 1990s.  He commented that he began practice in 1977 the same year I had.  He stated that in the late 1970s the University based endocrinology center he worked in would see 2-3 cases of type two diabetes in teens per year.  By the late 1990s they were seeing 2-3 new cases each week.

Telling of this trend, the common terminology in the 1970s was “juvenile onset” and “adult onset” diabetes, the former referring the autoimmune onset where the pancreatic insulin producing cells were destroyed and the later referring to the diet/lifestyle origin disease.  So many juveniles began developing adult onset that the terminology was changed to type one and type two diabetes.

The impact of all of the above problems has been buffered somewhat by medical care, primarily drugs.  We appear to be closing in on the limits of that approach to mitigate these trends, yet the public seems to have unwavering faith that no matter what they do to themselves, medicine can undo it.  That is a “faith” that is blind to the facts.  The GLP-1 drugs that are all the rage currently for weight loss and diabetes treatment have some benefit, but they also are simply delaying the reality of this blind faith.

We all need to take a hard look at our own lifestyle.  Leaving it to “the system” to fix appears to be failing.

1. Shmerling Rh.  WHY LIFE EXPECTANCY IN THE US IS FALLING: COVID-19 AND DRUG OVERDOSES ARE THE BIGGEST CONTRIBUTORS. Harvard Health, October 20, 2022.
2. Olshansky et al.  A POTENTIAL DECLINE IN LIFE EXPECTANCY IN THE UNITED STATES IN THE 21ST CENTURY.  N Engl J Med, 2005;352:11.