If you exhale you’ll probably find you sink quite well. And ‘jumping’, even just using your feet/ankles will be enough to move you up 5-8 feet. Give it a try (assuming you can swim!)
It also depends on the type of fat. People with high density fat (like me) can be 100 pounds overweight (or more), and still be negatively buoyant. I have to work to stay afloat.
My wife has low density fat, and she can't sink or dive for love or money.
Generally (assuming a healthy weight) women float and men sink, due to women having a few percentage points more body fat. I imagine children sink as well as men though.
For high school wrestling we got body fat analysis done. The, fit and healthy, women on the team were in the %30s while men down to the single digit %.
Fit women (just regularly fit, not even athletes) have body fat percentages in the 20s.
And unless all of you had been cutting for an event (in which case, why weren't the girls also doing that?), I highly doubt all the boys on your team had body fat percentages in the single digits. See e.g. this random sampling of NCAA wrestlers[0] with an average of ~14% body fat even excluding heavyweights.
Not to mention that describing high school students as "men" and "women" casts a fair bit of doubt on this story ever actually happening.
Yes, that's what I'm saying - unless you are quite obese, your body fat will not be so huge a factor that it will cause you to float with your lungs empty. You might not sink quite as far but still.
