Withings scale accuracy for TRENDS

There are studies that looked at ratios of fat to lean mass lost in various weight loss scenarios. I don't have any of those at my fingertips or bookmarked, but it should be relatively easy to find some, or to find summaries/reviews from some of the better blog-y sources.

Examine.com, usually a decent source IMO, says this in one of their articles:

When you lose weight, some of it will be fat loss, and some proportion (usually around 25%) will be lean mass and/or muscle mass. It should be noted that lean mass loss is not always muscle mass loss per se, as lean mass comprises muscle, but also bone, connective tissue, organs, and body water content. The goal of most fat loss programs is to improve body composition — in other words, to increase the body’s proportion of lean mass to fat mass.

That's from an article about GLP-1 drugs, but a general (not GLP-1 specific) comment. This is the link, but I don't know whether it's subscriber-only content:

https://examine.com/faq/will-weight-loss-drugs-cause-me-to-lose-muscle/

Of course there would be variation around the mean in the studies, anyway, so your n=1 could vary. You look to be around that neighborhood in your Withings stats, and not exercising might drive the individual results to a slightly higher proportion of lean loss alongside fat loss. There's also that relevant comment about lean mass vs. muscle mass, and I'm not sure what components Withings estimates.

For lean mass specifically (not just the muscle mass), I'd say we want to lose some of that - I'm thinking I don't need the same total blood volume I did, for example, when there was nearly 40% more of me.