Ionic's calories burned

[JavaShipped]

Hi all,

I know that there are numerous posts on this topic, but I couldn't find anything to help this. My calories calculated by the fitbit are way out of wack.

I set my self a little goal/project to loose some weight, I've gained nearly 20 kilos this year, due to new medication and a lifestyle switch after a job change. I got myself a fitbit Ionic and girlfriend who runs marathons. 

I calculated my BMR, which for a big guy as I am now(180cm, 123kg) is 2582kcals. I then slammed in my measurements into the fitbit and off I go, letting the fitbit get a grasp of my routine and calorie expenditure. It was high, and I wondered why, I was basically sedentary the whole day except for a little walk every day. The calories burned didn't drop over time (I've had the ionic about 5 months). 

The fitbit says on a day I basically do nothing (no walk), I burn around my BMR (2400cals), which makes sense, even though its pretty high. But then I do literally any exercise, and it just goes wild. 6k steps (a very modest amount) gives me nearly 4k calories out. I freelance UI design in the week and delivery pizza on the weekend, and thats where my steps come in (I pace the shop and there's actually a lot of walking to and from doors, more than I thought), and 6k and approx 4k calories is normal. I did a 5k with my girlfriend (a shameful time) and it said I burned nearly 6.5k calories that day. thats almost 1000cals per km, which is insane. 

So I set out for a week to follow a calorie deficit (strictly) of -400kcals (from the fitbit calculation). I also took 10% off the calculation (so 4000cals calculated is now 3600). I was strict with this for 1 week and gained weight, nearly a kilo. This was following the same fairly sedentary routine above.

Then as a further experiment I did a 400 deficit from my BMR for a week (2682), no 10% deduction this time. Again, I was strict with this, I could under eat but never over eat. Again with the sedentary routine above. And I also GAINED WEIGHT (about half a kilo). 

I'm not sure whats going on here. Are my meds messing with me? Am I calculating my BMR wrong? Is fitbit just lying a little?

Moderator edit: Updated subject for clarity 

[SilviaFitbit]

Welcome to the Community @JavaShipped. Thank you so much for taking the time to share your experience with your Ionic and calories burned. 

I'm glad to hear that you're exercising more. I'll be glad to help you clarifying the data you're getting. 

I would like you to make sure that your personal information is properly entered in your Dashboard, this will ensure that your exercise is calculated properly. You can learn more about it by checking this article: How does Fitbit estimate how many calories I've burned?

Since, you have a watch that has heart rate, you can try these tips to improve your heart rate reading on your Fitbit device. 

Last but not least, you may want to check this article about how do I track my food with the Fitbit app? 

I'll be around if you need further assistance.