First the good:
As a picture of a small town in the years of Trump, and people with very different lives finding common ground and some mutual respect, it's a good one. I liked the characterisation and the humour and the descriptions. Also the ending, whereby the protagonist sacrifices himself in order to, as he suspects, save the world from some kind of sentient alien lifeform, is low-key and strangely optimistic compared with previous stories with a similar theme (it's one he likes) by the same author.

Now the rest of it:
- This uses the same idea as a story by HG Wells and while a simple idea is not copyright, I could but wonder if there was a Terry Pratchett-style concealed pun in there somewhere. I mean, who ate all the pies? Maybe his suddenly revealed cooking skills could lead him to open a craft pie shop and what would he call it? For it does read like Edward Lee (in one of his gentler moments, as this is far from horror) had rewritten "The Truth about Pyecraft."
- As we know from our Star Trek, "ye canna defy the laws of physics, Captain!" Just because someone has lost a lot of weight and even if they have the same strength they had before does not necessarily mean they can run faster. Admittedly as the syndrome develops Scott does lose the ability to maintain traction on slippery ground - this is well done. But I wasn't convinced by it as it applied to the run. Years ago there was a tyre advert that had a well-known athlete (Linford Christie?) wearing very unsuitable footwear. The tagline: "Power is nothing without control." I thought of that when I read this. Newton's. Third. Law.
The author doesn't get running. You have a former Olympic-class distance runner in a town which is going to host a 12k (I don't mind this being an odd distance. One of the regular races around here is a 7k, which is also a peculiar distance. This year it sold out months ahead). She is probably going to be heavily involved and if the race is such a big deal that no local has won it for years, it will probably be sold out some time in advance. In the same way that writers write, runners run. It's what they do.
She placed fourth female in the New York Marathon, which if it was this year's race would give her a time of 2:26:21 - the time achieved by the Kenyan Nancy Kiprop. Using the Race Time Predictor she would do a 12k in 38:55; and a 5k in 15:23 which would net her the women's parkrun record by 27 seconds. Running, even a middle-distance race like a 12k (and this one involves at least one big hill), isn't just a matter of having extra strength (that is arguably more the case in the sprint). It involves training and tapering, technique, pacing, breath control, and a host of other factors. I don't think Scott can do a 12k in 38:56. I just don't.
I didn't even mind the 'phenomenon' being unexplained, because it's actually fantastical, but so much else made me think 'what?'