Edge case: people who are in the process of changing their body size/shape. Growing children, people losing weight, people gaining weight (they're out there), will all occasionally want to buy for where their body is going to be in the future, not where it is now. How to accommodate them?

I'm sure models predicting how their body changes (based on various parameters and previous scans of the particular person and other people) could be built, allowing to optimize for longest time period of "decent fit" at the cost of "perfect fit now".