My gym has a digital scale which measures, among other things, body fat and muscle percentage. I'm not driven by the scale, but each January I use its recordings as an assessment and benchmark. I had modest expectations for this year's reading: I increased my gym trips (from 3 to 4-6x/week), lifted heavier weights, completed two distance running clinics and added (admittedly irregular) yoga and Pilates. But when I stepped on the scale this year -- no change, not even a little bit. What gives?
Here is the thing with body fat measurement scales: they are not as accurate as we would like to think they are. There are many factors that can affect the numbers you see when you step on the scale. Things like how hydrated you are, or how much caffeine you have consumed, or where you are in your hormonal cycle, or how much salt you have consumed or even what time of the day it happens to be when you stand on the scale will all play a factor in the result. Do not allow yourself to be too discouraged by this plateau.
Like you said, you are not driven by the scale so instead take a look at how fit you have become. You are exercising more, you are lifting heavier weights and you are training harder. However, because of this increase in physical activity you may also be finding you are eating more which in turn is not improving your calories in and out ratio. I do not know for sure as I do not know what you are eating or how many calories you are burning but that could be a possible reason for the plateau you have experienced.
I see this problem all the time -- people increasing their activity but also increasing their calories in and then wondering why after training for a marathon they weigh more than they did when they started. You have to make sure that you choose foods that are rich in nutrients, low on the glycemic index and full of fibre and protein rather than sugar. Take a look at your diet or follow a fitness app like MyFitnessPal to see if your diet is balanced. The only way to decrease your body fat composition is to improve your nutrition, decrease your stress levels, increase your water intake and make sure you are getting enough sleep.
Continue with the great training you are already doing but focus more on what you are putting into your body. Try the scale once a month and see if you start to see a change but don’t make that your sole focus. Work on continuing to lift heavier, run farther, and trying new things.
Attached – John Krasinski after a workout.