Burning less than "typical adult"?

[SunsetRunner]

I've been on the weight-loss diet since April and now I maintain my weight and overall fitness level. With time number of calories, I've been burning daily went down. I remember in the beginning, with not much of exercising I could easily see 3500kcal burnt in Fitbit but -20kg later I can barely reach 3k. This is only when I exercise and I'm talking here about running several intervals for 10km or up to an hour. If I don't exercise I barely reach 2000kcal. Now, 10:54pm, Fitbit shows 1926kcal so far ( I did light spinning for 30 minutes today, so it added few more kcal ). All guides say that typical adult burns 2k daily which more or less matches me. Other guides say that men burn 2,5k and women 2k. 2,5k is a very intense day for me! I believe that my rather small body "dimensions" ( height 5'1, 54.7-55.0kg ) and quite low RHR ( 46-47BPM, interesting that whenever my HR goes below 46, Charge 2 shows two dashes - hardware limitation? ) indicate that I need very little energy to be functioning which I think Fitbit does calculate more or less right. This makes weight maintenance lot more difficult ( one typical pub meal would give me way more energy than I actually need! ). I'm wondering if anyone experienced such thing. Probably it's not very common among men as typical man is way taller. It also gave me an interesting insight into what had actually happened that I gained weight in the first place. I used to sleep a lot during weekends ( sometimes most of the day ), after waking up I used to order some fast food delivery etc. If indeed my energetic needs were that low, I just gave myself "fat gaining treatment" in accelerated rate. Now I came to the realization that more than other adult men I need to keep an eye on what I eat and how much and better if I don't quit exercising.

Did you notice such a change in your body during a weight-loss process that it was harder and harder to burn more calories daily up to the point that at the end of your regular day ( and mine still involves some walking at least ) you may not even reach 2k calories burnt?

[Dominique]

If I got the numbers right, you went from BMI 31.2 (lower end of obese category) at 75 kg to BMI 22.9 (middle of normal weight category) at 55 kg in just four months (April to August). That’s a huge change in such a short period, so some metabolic adaptation definitely took place. This means your metabolic rate is probably lower than that of a person your age and your size who has maintained the same weight for a longer period of time. Your metabolism should pick up again as you’ve switched to maintenance, but it will take some time.

[Daves_Not_Here]

@SunsetRunner wrote:

Did you notice such a change in your body during a weight-loss process that it was harder and harder to burn more calories daily up to the point that at the end of your regular day ( and mine still involves some walking at least ) you may not even reach 2k calories burnt?

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I'm nowhere near you yet (and congrats on your success!), but, yes, I find as I lose weight, I need less food and need to continue to reduce intake to maintain a calorie deficit.  Also, my heart rate doesn't increase as much as before with exertion, so my activities now burn less calories.  I view both of these as positives, and figure I just need to lower my appetite to match my lowered energy requirements.  

My father in law lived to 95, was very active, lean and mean, and ate like a bird.  Somehow, overeating for pleasure was just not an inclination of his.  Something to be said for that.