Calorie deficit but increased weight?

How are you tracking what you eat? If you are gaining instead of losing you are either burning less than you think you are and/or eating more than you think and are not in a 500 a day calorie deficit.
Do you weigh everything solid that enters your mouth with a set of digital scales? When I say everything I mean everything, including oils, butter, prepackaged food etc
Don't use measuring cups and spoons for anything that is not a liquid because using them for solids is very inaccurate.
Once you have weighed do you check against nutritional labels and the USDA database to ensure that the item you have chosen from the database is accurate? It is user based entry and some are shocking when it comes to accuracy.

This is an excellent thread for why you should weigh everything.

https://community.myfitnesspal.com/en/discussion/10634517/you-dont-use-a-food-scale#latest

I found my Fitbit to be wildly inaccurate when I had one. I'm pretty sure that the Fitbit uses your heart rate to estimate calories burned. While lifting, your heart rate may go up, but you may not be burning as many calories as your increased heart rate suggests. "While a heart rate monitor (HRM) can be used to calculate calories burned during aerobic workouts, the relationship between heart rate and calorie expenditure is not the same during a strength training workout, so whatever your heart rate monitor may tell you is likely inflated because it thinks you're doing cardio (not strength training)." https://www.nbcnews.com/better/diet-fitness/your-apple-watch-or-fitbit-making-you-fat-n764066

PokeyBug wrote: »

I found my Fitbit to be wildly inaccurate when I had one. I'm pretty sure that the Fitbit uses your heart rate to estimate calories burned. While lifting, your heart rate may go up, but you may not be burning as many calories as your increased heart rate suggests. "While a heart rate monitor (HRM) can be used to calculate calories burned during aerobic workouts, the relationship between heart rate and calorie expenditure is not the same during a strength training workout, so whatever your heart rate monitor may tell you is likely inflated because it thinks you're doing cardio (not strength training)." https://www.nbcnews.com/better/diet-fitness/your-apple-watch-or-fitbit-making-you-fat-n764066

That's interesting. I find my fitbit to be very accurate. It has only helped me with my fitness goals.

annikahoefermann552 wrote: »

Hi all!
I have a little bit of a situation. I have been in a 500 calorie deficit for three months now (with minor changes when travelling, where I tried to stay at maintenance). I have been lifting progressively 3 times weekly as well as HIIT workouts 2 times a week. Other than that, I take about 20.000 steps a day.
I’ve done this since the beginning of August. Before that, I lost a lot of weight due to stress and eating waaaaay to little (lost about 10kg in 3 months).
Since August i went from 66 to 70, although I was in a calorie deficit. Can that be muscle? I read somewhere that muscles weigh more but I’m unsure.
I can see some changes especially in having more muscle and being stronger, but feel like I’ve also gained fat.
Im 179cm and now at 70kg.

Emphasis above is mine...

In general, unless you are a novice, it is virtually impossible to gain muscle without being in a caloric surplus and without gaining some fat in the process - unfortunately the body is not efficient enough to only add muscle in a surplus. You have to have a source to build the muscle from.

Conversely, it is almost impossible not to lose some amount of muscle while in a caloric deficit. Unfortunately the body is not efficient enough to only burn fat. It will pull energy from multiple sources. So in a deficit, the best case is to preserve the muscle you already have.

Applying that to your case leads me to believe that there is a logging error somewhere. Given your activity level, a 500 calorie deficit would seem to be easy to achieve. What does MFP recommend your intake to be? How old are you?