“…there are 4 factors that we can say (or at least I say) have contributed to the childhood obesity epidemic with relative certainty. These are:
- Sugar sweetened beverages (e.g. pop)
- Sedentary behaviour (especially screentime)
- Lack of sleep
- Adult obesity
People might be surprised that diet and physical activity aren’t on that list. But really, it comes down to measurement issues. It is certainly plausible that diet and physical activity contribute to increased childhood obesity rates. The problem is that the historical data for both of these variables is really weak, and often contradictory. The data for sugar sweetened beverages and screen time isn’t of much better quality, but the findings for both of those outcomes is much more consistent than for physical activity or diet more generally.
Note the absence of environmental pollutants.