I’m working on getting myself fit again. No more excuses. I’ve bought a Fitbit to help me achieve these goals. So today, my Fitbit tells me I’ve used 4699 calories. I’ve consumed 2204 calories. So that’s a 2055 calories deficit? Shouldn’t I be hungry?
2055 calories would be roughly equal to running 17-20 miles (depending on your size and fitness).
Did you work out for 3-3.5 hours? 
Double check the data you entered to enable the Fitbit to make it’s calculations.
I just double checked the information and it is right. I did do a lot of exercise today although I definitely didn’t run 17-20 miles. Very strange. The calories usage spikes match the period of exercise I did today. I thought maybe it was reading my BPM as too high and so overestimating my base metabolic rate, but I double checked those a few times today with my blood pressure machine. Now I’m very perplexed.
Next: What exercise did you do?
I walked about 7.5 miles, a little over an hour of martial arts (mainly just hitting a heavy bag so equivalent to boxing I guess) and then tonight I played a couple of VR games (the type where you move a lot) for about 45 minutes, so maybe roughly equivalent to aerobic exercise. So I checked a couple of calculators online and they say my BMR is 2281 calories/day. If I look at the points during the day when I’m not moving around much and add them up it is pretty close to 2281, so I think it has the BMR right. I checked a couple of calculators for walking and they’re saying that given the distance and time it should be about 1,000 calories. I checked a calculator for boxing and it says that it should be about 1,000 calories. I checked a calculator for aerobic exercise (low impact) and it says it should be about 400 calories. So 2281+1000+1000+400 = 4681. Which is pretty close to 4699. Of course it is still going up at my BMR.
P.s. - thanks for your help running coach
Not-so-knowledgeable person here – but – do I not understand correctly that strenuous exercise depresses the appetite? At least for some period of time?
Did you feel ravenously hungry sometime later on?
If this is correct, can someone 'splain me why?
I’m going to sleep soon and I’m a bit hungry now, but I just feel like, shouldn’t I be really hungry if the deficit the Fitbit is telling me is right?
I know I overate for lunch today. I’m trying to keep in my calories intake lower than what I did today, which is why I did the extra VR workout this evening to compensate.
Something is off in the attribution of calories to various activities. Hitting a bag =/= boxing. It’s quite unlikely that walking for 7.5miles will consume 1000 calories. It’s possible but quite optimistic that playing VR games for 45 minutes is equal to 45 minutes of aerobic exercise. Burning 4000 calories a day is the stuff of special forces training, not a few hours of light exercise.
If you’d really expended 4700 calories, you would likely have gone into ketosis and you’d know it.
If you want to lose weight, it’s mainly going to come from calorie restriction. Exercise helps but it’s mainly about eating less carbs.
Fitbit uses a special technique to calculate out the calories to display on your screen. It’s called… (What was it again?) lying.
First of all, you cannot track your calories so closely that you are within a single calorie. You sure you ate 2204 calories and not 2203? You’ll be lucky if your calorie count is within 20% of what you recorded no matter how meticulously.
Second of all, eating 2200 calories is a pretty decent amount of calories to eat. Unless you’re really training for a marathon, you shouldn’t necessarily feel hungry eating that many calories per day. It’s not really a deficit.
Now, that doesn’t mean you should give up using your Fitbit, but unless you’ve ran eight to ten miles that day, there’s no way you burned 4700 calories. Plus there’s been recent questions on the whole calorie in/calorie out theory.
None of this means you should quit since it’s impossible. If you look at an apple and it has somewhere between 80 to 110 calories, and you look at a Cinnabon at 1300 calories, you can probably assume the apple is less fattening. Using calories to let us know just a round number of many calories something has can help us make intelligent eating choices. For example, the Southwest Chicken Ranch Salad at McDonalds has over 500 calories – probably a lot more than you thought something with the word salad in it should have. If this gets you to eat less highly processed foods and load up on veggies, so much the better.
I have an Apple Watch which also tells me my active calories. I don’t know how accurate it is, but I try to do over 900 active calories every day. I wake up in the morning and run/walk six miles. I walk everywhere, and if it’s 10pm, and I look at my watch, and it says I only burned 700 active calories, I get out there and burn those last 200 calories. I have no idea how many actual calories I burn, but I still use my watch to keep me active.
So, don’t take your Fitbit word. Fitness trackers tend to over estimate calories burned because people like that. Calorie tracking and counting with laser accuracy is pretty difficult to do, but knowing calories can help you make better nutritional choices and you can use that Fitbit to help push yourself and keep you active.
2 cents…
Don’t try to “get” fit. It’s the wrong mindset. What you want to do is “be” fit and that’s a similar but significantly different thing in terms of how you achieve it. To “get fit” you do things like buy a Fitbit and count calories and be all serious about your exercise regimen.
To be fit, you have to develop a lifestyle that automatically results in the body you want. It’s a lot harder to do but it’s the only thing that delivers long term results.
You know what you need to do, so start doing those things slowly and in incremental steps you’re comfortable with. If you know you’re eating too many carbs, then look for ways to cut down on carbs that you can live with for the rest of your life.
That’s the real key… “the rest of your life.” Whatever changes you make to how you eat or exercise or rest and recover, they have to be something you can do for the rest of your life, basically on automatic pilot, or it’s just a stunt.
Throw the Fitbit away. It encourages short term thinking and this is a long term deal. It’s the rest of your life.
I’ve has the same thing happen on days when I did a lot of activity. On days where I hiked for 3+ hours I may run a deficit of 2000-3000 calories and not feel hungry.
I appreciate the advice. It is worth noting that before being injured in the army I was always fit/healthy. I gained a lot of weight after being injured and then, well to be honest, used the injury as an excuse to just not get healthy again. One of the last things my father said to me when he died recently was “Get healthy.” And he’s right, time to stop making excuses and do it. So again, I appreciate the advice. With respect to the fitbit, I actually really like it because I feel like it is mocking me, like it is saying “I bet you won’t do this” and I don’t want it to win. So for me I think it is helpful.
I was thinking today about what it was like back in the army when we would be in the field on exercise, and I remember thinking I experienced this quite a bit. So in hindsight, I think maybe it isn’t that unusual of a feeling.
With respect to the other replies, I’ve decided to take an experimental approach towards measuring the accuracy of the fitbit. This will give me an error and I can use that to compute a lower bound of calories burnt, which will help. I talked to my doctor today and she thought that was a good idea and that the fitbit should be helpful both because of my personality (Oh you don’t think I’ll get up and get moving! Ha! In your face Fitbit!) and will give me a good enough approximation of being under calories consumed. Plus the ease of use of tracking what I’m eating is helpful to change me back to the way I used to be.
Is hunger really triggered by calories in - calories out, or is it triggered by the presence of bulk in my stomach? It seems that a bag full of carrots does a better job of ending feeling of hunger than a bag full of M&Ms.
I have a FitBit as well, and I find it handy to track activity and such.
Like you, I like being challenged by a little electronic nag; it’s very effective. I recommend doing some of the Challenges in the FitBit app. They’re sort of “virtual races” that take you on one of several different courses. Downside: there’s only 6 courses, three in New York and three in Yosemite National Park. Upside: the scenery they show you along the trips is seriously making me want to hike Yosemite and other beautiful outdoor spaces.
Walking is working for me. Got my 60 pound weight loss badge yesterday, but that’s only since I got the FitBit at the end of April; it’s more like 100 overall.
Wow! Congratulations! 
It depends on how much the person weighs, does it not? According to my own pedometer’s metrics a person who weighs 255 pounds would burn 1000 calories by walking 7.5 miles (or at least I think I figured the weight/calorie ratio from how many calories I allegedly burn at my own weight correctly…). Weather or not that’s more or less accurate than a fitbit, I have no idea. This chartcomes very close to agreeing, actually.
I want to gather some more data, but I walked 8 miles today @ ~4.1 mph. I added up all the calories reported during the period I was walking and subtracted out my BMR and the FitBit was over by 4%. That’s not too bad and more than suitable for my purposes. That being said, I’m not concluding anything yet. I’ll gather data for the rest of the month and see how it does. My goal, as mentioned above, is to compute an error and then that will give me a lower bound, which again for my purposes is more than enough. Additionally, I’ll be able to double check what it claims for calories burned vs weight loss and see if they match up reasonably well.
Tomorrow is a walking & gym day, so I’ll see how it does with that. From what I’ve read online, it seems like it does better at estimating calories burned from walking/running then it does from other exercises. So if in a couple of weeks if I find that this is true there’s a very easily solution for me, I won’t wear it in the gym. Any extra calories burned in the gym is a happy little surprise bonus.