Toys are relative -- the iPhone was not a toy compared to other phones but definitely a toy compared to a personal computer.

We built a stationary bike called Revvo (http://revvo.co) -- which does a lab quality VO2Max test but makes it a whole lot more fun. Not a toy compared to other exercise bikes but definitely a toy compared to a $45k metabolic cart used for lab tests.

Great article - we saw the same lack of correlation between activity level and weight when analyzing data from 750+ fitness tests:

https://hack.fitness/2017/04/09/what-we-learnt-from-750-fitn...

Increasing activity however does have a positive impact on your fitness (specifically VO2Max) -- the challenge is that this increase in fitness is invisible to most.

That's a big part of the reason why we started Revvo (http://revvo.co) - to make it easy to measure the vital but often invisible elements of fitness.

The authors only looked at weight and BMI, and not bodyfat % or lean mass, which are much better indicators of health than weight or BMI alone.

Someone who is 6' and 200 lbs could either be a body builder or a coach potato, and they'd have the same BMI.

Sure -- but body fat won't change much with aerobic activity (such as running) without also impacting weight.

About Revvo: I think the bike should be better designed i.e. similar to indoor road bike trainers.

we actually integrate an indoor bike trainer (wahoo kickr).

Nate's approach is based on evaluating the quality of the various polls - which is the thrust of the FT article. In fact he actively weighted each of the polls & corrected for known biases.