I've been an activated reservist.
Once pre-mobilization training begins, you either get in shape or get thrown out. There are indeed some fat fuckers who slip through the cracks, and some dudes do get wounded/injured and end up getting fat because they can't stay in shape.
Regardless we are still the best trained and equipped force on earth.
PERIOD.
Furthermore even if the entire military disappeared by magic, all the armies of the world wouldn't stand a chance attempting to occupy Texas alone because we have millions of citizens with scoped rifles who blow the heads off of white tailed deer on an annual basis.
So go suck a dick commie troll.
You will always have some slip through, but as you said, few last for very long.
I was Active from 2007-2012, and have been in the Reserves since 2012. And all of my units have been pretty proactive in weeding out those that can not pass a PT test. Generally fail more than 3 in 12 months, and out you go.
And the real measure is not weight, it is body fat. Myself, I have not passed the "Height-Weight" standard since I joined in 2007. But I was 42 then (53 now), and always come in under my allowed body fat percentage.
The only time I was ever in danger of being kicked out for weight was after I was injured when I was in the Marines in 1990. I was in the Infantry, and ran an average of 25-30 miles plus every week, in addition to all the other physical things I did. And back then, chowing down on a Triple Whopper with heavy bacon every day was not a problem.
But after a motorcycle accident trashed my knees, I literally went overnight to not running again, and it took me almost a year to get my weight under control again. I ballooned from 170 to 225 within 6 months, but then was able to drop back down to 180 within another 6 months through changes in diet and lots of walking (limping with a cane really).
But I do agree, the current generation is fatter than my generation was in the service. In my first 10 years I never saw anybody put out for weight. We were simply worked to hard to put much weight on at all. Soldiers today are much softer.
Even at the age of 53, I have yet to serve with anybody (other than a few reclassed Infantry types) who can keep up with me in my 2.5 mile walking PT test, or a ruck march. The condition of the current generation to me is rather horrible I must admit.