My DS experienced this last year. DoDMERB had him heavy, well I say DoDMERB, but it was the local contracted medical office. He is a broad kid and was going to be close but he was under according to 3 scales we had access to. The contracted site left his shoes and clothes on and recorded that weight and he ended up just over by a couple lbs.
After that, he had to fill out the measurement form, O-220 I think. He had his school nurse do the measurements and new weigh in. So prior to the new weigh in, he got a sweatsuit and dropped 4lbs. So, now he would be under weight, but still had to do the tape. Using a tape on the human has some variation and I think she was a little generous so the measurements were ok. It was unnecessary pressure for him because if he had just dropped weight ahead of DoDMERB, he could have avoided the extra check.
So, now fast forward to weigh in at BCT. At 5'10", he has to be at 175lbs for USAFA (Aside: USNA and USMA have 191lbs max for this height, as does active duty USAF, so 175lbs for USAFA seems odd). For weeks leading up to I-Day he is working out checking weight, etc. He is consistently 178lbs running 45mins day and working out 90 mins every other day in addition. He is doing bare minimum calories, fasting a couple of days, and still not below 175. I finally told him I didn't want him doing crazy diet stuff so just go with it as is and deal with it at USAFA.
At weigh in, they weigh him at 190lbs. Clearly the scale is off, he has been tracking his weight everyday for weeks and knows this isn't right, says it doesn't look right but doesn't make much of an effort about it since he is worried/nervous about the whole I-Day and they just mark it and leave him be. Since there was no one yelling at him for it, he let it be. The following week, he weighs in and he weighs in at 182lbs (with clothes). So this scale is probably right. Now they think he has lost 8 lbs in one week and give him Boost drinks to drink every day. He's writing home saying, holy cow, I need to lose weight and they want me to drink sugar milk. The following week, he weighs in and is 181lbs so now they tell him to drink two Boosts every day. He says something, but was told to do it anyway, they are worried he is losing too much weight. Now, he is thinking he should pour them out in the sink because they are almost all sugar and if he drinks them he will just get heavier and he also knows the initial weight was bogus so their instructions are based on bad info. But, he is worried that its an Honor Code Violation if he disobeys the order so he does what he is told.
His weight has stabilized around 180lbs and I haven't had an update lately.
I understand that during BCT they are monitoring them for health and the weight regs are less important than making sure everyone is staying healthy and not having significant weight loss during this period. He is still waiting to find out what the next steps are, if any. But, I completely agree with the above. This is a level of stress that can be completely avoided if you just make weight...and speak up if the scale is obviously off, but how many kids want to speak out on I-Day?