Sorry for the late reply: I actually had to do some work.
Algher, your earlier post implied that only those participating in the high adventure activities were required to get a physical exam (and I was lazy and didn’t check the link you provided); I am VERY glad to see that is not the case. (Although the official webpage does have me wondering how exactly they are accommodating the wheelchair-bound kids, or if they are in fact unable to attend the Jamboree because they can’t meet the mobility requirements of the site, despite being technically allowed to come. That bit’s unclear.)
Troppus, here’s a quick primer on BMI and why I have problem with the way its being used here.
BMI is simply the number you get when you divide a person’s weight by the square of their height. It’s in essence just a fancier version of those old height/weight charts. It does NOT measure fitness (obviously - how could it?), and it can be quite misleading when it comes to adiposity. A person who’s in fantastic shape, with tons of muscle and a very lot bodyfat percentage, can measure as obese (potentially even morbidly obese) on those BMI charts the CDC uses. Far more problematically, someone who has little muscle mass can have an excessively high percentage of body fat (including visceral body fat, which is metabolically the most dangerous stuff) and measure in the normal range on the BMI chart. (Remember those weak and wobbly elderly birders you referred to in one of your previous posts? This is where they fit!) For this reason, BMI should NEVER be used alone as a measure of obesity or fitness. It’s strictly a quick-and-dirty screening tool, and should never be used on its own to diagnose either obesity or “healthy weight.”
Now, here’s where things start to get really interesting. The old thinking was that obesity itself (defined by excess adiposity, not BMI) was causative of all sorts of nasty health problems. But newer research has has shown that it’s more an indicator of other underlying problems than a direct cause of problems itself. It’s quite possible for someone to be fat but physically fit - and those folks don’t seem to have any greater risk elevation for heart attack, stroke, diabetes, etc., than the “normal weight” folks, oddly enough. More alarmingly, thin people who are sedentary DO have increased risk - and recently a condition known as “normal weight, metabolically obese” has been identified in seemingly thin people. These folks, though thin, have all the parameters of metabolic syndrome (especially insulin resistance), have a greatly increased risk of cardiovascular problems and diabetes, and when you do an MRI scan on them, they have high levels of visceral fat (which is invisible to the naked eye). Despite how they look, they are very unhealthy! (And they represent about 25% of the “normal weight” adult population, so their numbers are not small.)
So when people focus on BMI, they are focusing on the wrong thing. What matters most of all is fitness. As a pathologist I don’t have the opportunity to sign off on those permission forms, but you can query Dseid (who specializes in pediatric obesity treatment) and you’ll see he’ll back up what I’ve said. In kids, I’d look for underlying cardiac problems via an EKG, and I’d check blood pressure and a metabolic panel to look for signs of metabolic syndrome - but I’d focus especially hard on fitness (rather than fatness, or the lack therof). Most fat kids are going to be unfit, but not all. And you’ll find a surprising number of skinny kids who are unfit as well, and shouldn’t pass the physical for this sort of trip.
If Kid A plays on his school soccer team, goes mountain-bking every weekend, and his Scoutmaster reports he completed a tough 10-mile hike two weeks ago with no problems, he’s fit. Who cares what his BMI is? And who cares what his weight is (as long as it doesn’t exceed the load limits of any necessary safety equipment)? He’ll have no problems at a high adventure camp, so to Hell with his BMI, let him go.
If Kid B’s favorite activities are reading and videogames, and his Scoutmaster says he struggled on the troop’s 5-mile hike two weeks ago, he’s unfit. (If his metabolic tests come back abnormal, he may have elevated long-term health risks as well.) Again, who cares what his BMI or his weight is? He needs to be limited to less-strenuous activities until he gets his fitness up, whether his BMI is 25 or 45.
Now, you might say that using BMI as an imperfect proxy for fitness does no harm, but that’s not the case. We desperately need to get people to focus on improving their fitness, as a sedentary lifestyle is known to be unhealthy, and this growing focus on BMI as the be-all and end-all does the exact opposite. It falsely reassures people who should be worried, and worries people who actually have no cause for alarm. So why do it?
(The other, lesser issue is that Jamborees have traditionally been designed as inclusive gatherings, not Outward-Bound style “test yourself to the limits” gatherings - that was Philmont. So switching Jamborees over to Philmont-style events is a big change in Scouting tradition, but if the Scouts want to do that, that’s their prerogative. Still, it seems to me to be a bit like me saying I’d like to hold a Dopefest and would like a representative group of Dopers to come - and I’ve arranged for us all to gather at Phantom Ranch in August. The venue and the goal for the gathering don’t match up.)