Building H #59: It Doesn't Add Up
Last week Eli Lilly reported some impressive trial results for tirzepatide, its new weight-loss drug. Patients reportedly lost an average of 22.5% of body weight, or more than 50 pounds on average. Between tirzepatide and Novo Nordisk’s semaglutide (aka Wegovy), which had similar (if not quite as powerful) results, it appears that there will be good pharmacological options for the treatment of obesity.
These drugs will likely bring important benefits, relieve suffering, and reduce health risks for millions of people. (There are 140 million people living with obesity in the U.S.) The development of drugs like tirzepatide and semaglutide also plays into a dynamic that, paradoxically, holds the problem in place. Daniel Lieberman, the evolutionary biologist whose work we’ve featured often, coined the term “dysevolution,” to refer to the dynamic where treating the symptoms of disease while not tackling the root causes of the disease leads to propagation of the disease across generations:
“Although we often treat the disease's symptoms with varying degrees of success, we fail to or choose not to prevent the disease's causes. When we pass on those environmental conditions to our children, we set in motion a feedback loop that allows the disease itself to persist and perhaps increase in prevalence and intensity from one generation to the next."
The articles we selected for our focus on obesity in this edition also show that those root causes are not entirely clear. The prevalence of obesity has risen so dramatically – a tripling over 60 years – and we know that traditional genetics can’t explain the high growth (our genomes can’t have changed that much in two-to-three generations). Thus the causes are presumably behavioral, environmental, and/or the interaction between our environments and our genomes. Yet a series of articles in today’s edition point to the concern that the conventional wisdom about causes might no longer explain the unrelenting growth and that other factors might be at work. The nature of processed foods and how our bodies metabolize them, the presence of chemicals in the environment, changes in our gut microbiomes and epigenetic transfer of risk factors are all cited as possibilities. Pointing out that Americans’ levels of exercise and calorie intake have been relatively stable over the past 20 years (while obesity has gone from 30% to 42%), Dariush Mozaffarian, dean of the Tufts Friedman School of Nutrition Science and Policy, summarizes the evidence and argues that we must consider alternative explanations and rigorously evaluate them. And that we must make investments in this research with urgency.
Indeed we must. And, at the same time, we can’t let the uncertainty slow efforts to create healthy environments: Mozaffarian also points out that while we might not know the whole story on rising obesity levels, we do know the importance of eating healthy diets and of being physically active, whose benefits extend far beyond weight management.
- Steve & Thomas