I exercise but losing muscles instead fat.

Agreed with Lyadeia. Most BF Scales are inaccurate as hell.

The best way to monitor fat loss is by taking pictures/measurements and comparing.

Body fat % will change daily as will weight and hydration. Some days up, some days down. You need to track the results for a few months and see if there is a downward trend. If you really want to maintain and build muscle to burn fat you need to eat at a small deficit and lift weights.

couple of things, you should be eating alot more then that with that much exercise IMO and if you don't have a sedentary job thats more you should be eating just to maintain your current body mass and activity, based on the stats you gave your base Metabolic rate for just a resting state is around 1654 calories, then you add activity onto that and work out a reduction from the level of activity you do of no more then 20-25%.

you don't gain or lose muscle very quick either way. my biometric scale which is not a cheap one sais i haven't lost any fat % in months when clearly i have and i have gained muscle in arms and legs so i aint losing muscle either. it's also saying my Body Mass hasn't changed much in that time either yet my water has increased from 43% to around 54% over that time most weight fluctuations is water, the more you drink the more you can process and lose stored water, and how does it know what your lean body mass is if it's impossible for it to know exactly how much muscle and fat mass you actually have, no scales can do that, read this http://www.sport-fitness-advisor.com/bodyfatscales.html

do you lift weights or atleast do resistance training of some sort ? excess cardio can lead to muscle reduction if you don't supply enough protein to maintain and the old addage if you don't use it you lose it but IMO you'd have to have no excess fat to burn off b4 it even bothered going to muscle specifically i'm no expert tho obviously

and btw i'm 175cm and 87kg so you aren't much different to me. I do alot of cardio and didn't lose much muscle mass "that i know of" i can lift more and for longer then i could b4 so i have increased strength and visibly know for sure my arms and legs have grown in muscle mass but i do atleast an hour a week of weights/core training out of 6+ hours of intentional exercise, you also want your water weight to be in the mid-high 50's, the body is meant to be 60% water according to health guidelines to run efficiently.. intake atleast 12x250ml glasses or something that has natural waters in it a day, muscles need water but excess water or drinking to often and too fast would just be flushed straight out by the kidneys and liver.

i'd suggest getting a proper physical to tell exactly what your LBM, Fat % are and get some nutritional advice on how much to eat, could be hormonal too or could just be the scales are interpreting muscle as fat or also to consider food when digesting is still in your body and adds onto anything when you step on the scales. If you are losing muscle you'd notice it in a reduction in definition

If you are loosing weight you will loose muscle, the body will burn the muscle as well as the fat when you are burning calories. To stop this from happening you need to do strength training to keep the muscles built up, also increase your protein but lower your carbs. Protein doesn't need to come from meet it can come from things like bean, nuts and dairy products (yogurt, cheese etc).

It's been said, but to avoid losing muscles, you have to do strength/weight training and eat a lot of protein.

Also, those scales are not accurate at all.

1. You're not eating nearly enough protein. You should be getting about 1.5g-2g of protein per Kg of body weight.

2. DYEL? If all you're doing is jogging and you're eating at a caloric deficit, you will lose muscle regardless of how much protein you eat.

3. BIA is fine, as long as you take your measurements consistently under the same conditions (e.g., get on the scale first thing in the morning, before eating or drinking anything.) The more hydrated you are, the lower the BF% reading will be (and the higher the LBM reading) so measure while slightly dehydrated to ensure you're being given a conservative estimate of LBM. My BIA scale tends to overestimate my BF% / underestimate my LBM by about 1-2% compared to calipers — again, as long as I get on it first thing in the morning, while slightly dehydrated.