Weight seems to be almost the primary health issue here (Grandad smokes, and also mentions having to pay fines and higher taxes because of that, but there's no mention of a mind swap to help people quit those cravings). After a little leeway (about 20 pounds), there are fines for carrying excess weight (and random weigh-ins to enforce and track).
Suspension of disbelief plays a pretty important part in enjoying this novel I think. If science can actually create a "brainmap" capturing a person's mind(soul?) and insert it into another body ... surely they could have figured out some other (easier) ways to help people lose weight (I'm STILL WAITING for an implant that correctly calculates all calories going in, and calories burned. Seriously, I try to track, but who knows if the estimates are even close to correct!) And ... if such mind swapping technology exists ... it's limited to WEIGHTLOSS? Actually, that theme turns out to be a big part of the book's progression (hmmm, what else can we do if we can input someone's brain into another person's body ... endless unethical options).
Overall though, I did enjoy this read. On this constant journey to get to a healthy weight, it is interesting to ponder what people would be willing to do. To imagine what it would be like for the "reducer" ... to be taken from their fit and trim body, and placed in an overweight one (especially if it seems to have it's own cravings and temptations) and have to work their way down again. Wonder about the original mind being placed back into this new body ... would weight loss without the work have the same impact? Will they be able to keep the weight off?
This brought up some other interesting thoughts about how much your appearance does affect your personality and makes you who you are.
I'm not a fan of present tense, it just seems clunky and unnatural unless it's really well written. Well, nothing jumped out at me until well into the book (chapter 8). That's good. I picked this up for $1 (Kindle sale) and was happy with my purchase.