Body measurements

You're doing great, no need for stress or worry.

Yes, it's possible - inevitable, even - that measurements and weight both will go up and down, even when everything we're doing is perfect.

But it's significantly about water retention shifts, and those can happen quite quickly after something like eating extra sodium. Keep in mind that our bodies can be up to 60% water. Someone like you - not severely overweight/obese - probably has water as a larger percent of body weight than someone otherwise similar who's carrying much more body fat. (Context: I'm also 5'5", have been at your current weight part way through loss.)

Generally, on a time scale of weeks to a small number of months, measurements will also be affected by shifts in water retention, and will head in the same overall direction as scale weight through a combination of water retention shifts and body fat changes, but with variability along the way.

For many of us, retained water drops suddenly in the first couple of weeks or so of a new way of eating - lower calories, or reductions in sodium/carb intake, mostly, because water retention is needed to metabolize those healthfully. Sometimes, there will be a rebalancing in the subsequent weeks as the body adjusts . . . possibly looking like a stall on the scale, or a drop then increase in some measurements.

As a general rule of thumb, here's I think: Multi-pound shifts or significant measurement changes over a day or few are mostly about shifts in water retention or varied amounts of waste in the digestive tract on the way to the exit. (Fat loss is creeping along gradually in the background, playing peek-a-boo on the scale with the larger water shifts.)

In the trend of weight over several weeks, body fat changes start to become clearer from the direction of the body weight or measurement trend line. How many weeks is "several" varies, theoretically fewer weeks during fast fat loss, more weeks during more gradual loss . . . but for women with monthly cycles, it can be important to compare body weight and measurements to the same metrics at the same relative point in at least two different menstrual cycles.

I wish it were otherwise, but literal muscle mass changes - adding new muscle fibers - are more a thing of many weeks to months and more, quite slow. It's even slower for women, and for anyone in a calorie deficit.

Especially if new to exercise, we can get stronger quite quickly. That's mostly a result of better recruiting and using the muscle fibers we already have, a.k.a. neuromuscular adaptation (NMA). We can also start looking more "toned" fairly quickly, from a bit of a "pumped" effect from water retention for muscle repair. When NMA starts to have diminishing returns, but we keep challenging our muscles, that's when the body is more likely to start the expensive process of building new muscle fibers . . . slowly.

You're doing the right things, and as long as you keep up that great work, you'll make progress. Still, as Spring up there said so well, it's a process that takes time, requires patient persistence, and will look - in measurements and scale weight - like a long series of ups and downs, but on an overall gradual long-term down-trend in those metrics.

Best wishes for continuing success!

strongly suggest you bookmark the NSV thread over in Success Stories.

NSV aka Non Scale Victories helped push me long to success. I identified with each and every post.