Should I buy a used Fitbit flex?

swimmermama
swimmermama Posts: 526 Member
edited November 23 in Fitness and Exercise
I am having trouble gaining weight. My doctor suggested that I buy a fitness monitor to see how many calories I'm burning and adjust my rating accordingly. I have a friend who will sell me her Fitbit flex for $40. She has had it about a year.

My questions are: how accurate are the calories burned estimate from a Fitbit flex? Is a used on and the info I'll get from it worth $40? Any insight is very appreciated!!

Replies

  • beachbebe
    beachbebe Posts: 47 Member
    Even if accuracy is off, I think it will help you be aware of how much you exercise and, more importantly, help you gage your daily calorie needs accordingly.

    My body tells me I am eating too much with weight gain - even if I do not think I overeat, and my husband's body will tell him when he is not getting enough calories with weight loss - even if he thinks he has had enough to eat. Sounds like you are in the latter camp.

    I think your doctor must have told you that you need more calories and you must have told him he was wrong and you probably used MFP as your "proof" that he was wrong. Why else would he suggest you are burning more calories than you think unkess you argued that you eat enough calories?

    He sounds like a smart doctor to let Fitbit help you accept that you need more calories if you won't listen to your body and you won't listen to your doctor. It's a waste of your money if you know you won't listen to fit bit either.

    Your body does not care what fit bit says either...
  • jacksonpt
    jacksonpt Posts: 10,413 Member
    IMO, it's a mental thing.

    If you're having trouble gaining weight, then you need to eat more. It's that simple. How much more is the question. You can increase cals by 15 or 20%, then monitor for a month and see what happens, or you can get a fitbit or similar, adjust your intake based on the fitbit data, then monitor for a month and see what happens.

    Either way, you'll have to increase cals, monitor your progress/results, then tweak accordingly. The question is whether or not you'll feel better making those decisions based on fitbit data.

  • swimmermama
    swimmermama Posts: 526 Member
    Well, the story is that I'm eating close to 3000 calories and I'm a 5'8", 116 pounds, 35-year-old woman. She was curious about why my bmi is so low and suggested a Fitbit to see if I'm burning a ridiculous amount of calories during the day and to see about how much I should be eating.
  • jacksonpt
    jacksonpt Posts: 10,413 Member
    edited August 2015
    swimmermama wrote: »
    Well, the story is that I'm eating close to 3000 calories and I'm a 5'8", 116 pounds, 35-year-old woman. She was curious about why my bmi is so low and suggested a Fitbit to see if I'm burning a ridiculous amount of calories during the day and to see about how much I should be eating.

    OK, so what if the fitbit tells you that you're burning 2500 cals per day? Then what do you do?


    If you want to gain weight, you need to eat more. Either something is going on with your body that's causing it to burn more than the average (if it's something like metabolism, then the fitbit won't reflect that), or you're actually eating less than you think. Or both. But either way, you need to eat more if you want to gain weight.

    Ultimately, both cals in and cals out are estimates. Tweak how you estimate until your expected results reasonably match your actual results.


    Just for the sake of clarity... when you talk about gaining weight, are you talking about simple scale weight, or adding muscle mass (bulk, if you will)?
  • earlnabby
    earlnabby Posts: 8,171 Member
    The only issue I see with buying a used Fitbit is that you maybe have a year left on the battery (depending on how much she used it when she had it). Otherwise, I love my Flex and will eventually replace it with another when the time comes.
  • 999tigger
    999tigger Posts: 5,235 Member
    Mostly what jackson said. Are you walking about to your knowledge that you think you are burning masses of calories?

    How much exercise are you doing and of what type? Your name says swimmer, so am not an expert but i think the fitbit flex only counts steps and so wouldnt be able to assess your other exercise? No good if it doesnt do what you wnat it to. Leave that for fitbit experts though. I thought flex just moinotred sleep and steps.
  • swimmermama
    swimmermama Posts: 526 Member
    999tigger wrote: »
    Your name says swimmer, so am not an expert but i think the fitbit flex only counts steps and so wouldnt be able to assess your other exercise? No good if it doesnt do what you wnat it to. Leave that for fitbit experts though. I thought flex just moinotred sleep and steps.

    I think it monitors calories burned but I don't know how it computes that number. I'd love to know how accurate it is!
  • earlnabby
    earlnabby Posts: 8,171 Member
    swimmermama wrote: »
    999tigger wrote: »
    Your name says swimmer, so am not an expert but i think the fitbit flex only counts steps and so wouldnt be able to assess your other exercise? No good if it doesnt do what you wnat it to. Leave that for fitbit experts though. I thought flex just moinotred sleep and steps.

    I think it monitors calories burned but I don't know how it computes that number. I'd love to know how accurate it is!

    I have a flex and I swim. It counts my steps when I am in my water aerobics class, but it does not count anything while swimming. That is the only exercise I log separately so that Fitbit can factor it in. Overall, the TDEE it gives me (averaged over 30 days) is about 100 calories more than the TDEE I calculated using my real life numbers*, which is pretty close in my book. The more you wear your fitbit, the more accurate it becomes.

    * take the total number of calories eaten in a 30 day period and add 3500 for each pound you lost in that same period. Divide that number by 30 and this gives you your average TDEE. Only works if you are really accurate in your logging.
  • swimmermama
    swimmermama Posts: 526 Member
    earlnabby wrote: »
    The only issue I see with buying a used Fitbit is that you maybe have a year left on the battery (depending on how much she used it when she had it). Otherwise, I love my Flex and will eventually replace it with another when the time comes.

    Thank you! That is good to know!

  • discnjh
    discnjh Posts: 33 Member
    swimmermama wrote: »
    999tigger wrote: »
    Your name says swimmer, so am not an expert but i think the fitbit flex only counts steps and so wouldnt be able to assess your other exercise? No good if it doesnt do what you wnat it to. Leave that for fitbit experts though. I thought flex just moinotred sleep and steps.

    I think it monitors calories burned but I don't know how it computes that number. I'd love to know how accurate it is!

    It just computes that number based off of how many steps it measures you taking (with some adjustments for steps taken while running burn more calories). So any calories you burn in any way that doesn't register as a step won't be measured.

    I would be hesitant to buy a used one based on the number of people (including me) I know who have had theirs die within a year. I actually kind of think they're cheap enough to make that fitbit isn't terribly concerned if many of them end up getting replaced under warranty in the first year. My other conspiracy theory is that they're just trying to make money on all the extra bands you have to buy when the one that comes with it falls apart. ;)



  • swimmermama
    swimmermama Posts: 526 Member
    jacksonpt wrote: »
    swimmermama wrote: »
    Well, the story is that I'm eating close to 3000 calories and I'm a 5'8", 116 pounds, 35-year-old woman. She was curious about why my bmi is so low and suggested a Fitbit to see if I'm burning a ridiculous amount of calories during the day and to see about how much I should be eating.

    OK, so what if the fitbit tells you that you're burning 2500 cals per day? Then what do you do?


    If you want to gain weight, you need to eat more. Either something is going on with your body that's causing it to burn more than the average (if it's something like metabolism, then the fitbit won't reflect that), or you're actually eating less than you think. Or both. But either way, you need to eat more if you want to gain weight.

    Ultimately, both cals in and cals out are estimates. Tweak how you estimate until your expected results reasonably match your actual results.


    Just for the sake of clarity... when you talk about gaining weight, are you talking about simple scale weight, or adding muscle mass (bulk, if you will)?

    Thank you so much for your input!!

    I do strength training but need bodyfat as well as muscle. Im kinda seeing this as a "dirty bulk." I need to gain weight, period, and want to increase muscle while I'm at it.
  • 999tigger
    999tigger Posts: 5,235 Member
    Unless you are walking vast distances, then am dubious about whther the fitbit is what you want. Only you know what sort of exercise you are doing.
  • jacksonpt
    jacksonpt Posts: 10,413 Member
    FWIW... I had a flex for a while, and it did a pretty good job estimating total cals based on how I log/estimate. Notice I didn't say it was accurate, because I have no idea what accurate is... but based on how I estimated/logged cals, both in and out, my expected results were fairly close to my actual results.

    I also found that the longer the timeframe you looked at, the more "accurate" the calorie estimates were. So if I looked at the data for an hour-long workout, it seemed way off. But at the end of the day, total cals were about right.
  • 999tigger
    999tigger Posts: 5,235 Member
    So what is it you were logging? Steps or all workouts/ activity?
  • jacksonpt
    jacksonpt Posts: 10,413 Member
    edited August 2015
    999tigger wrote: »
    So what is it you were logging? Steps or all workouts/ activity?

    Me?

    I wore it all day/every day, so it monitored everything. I pay no attention to step data, only calories (which I think is based on movement).
  • editorgrrl
    editorgrrl Posts: 7,060 Member
    edited August 2015
    swimmermama wrote: »
    How accurate are the calories burned estimate from a Fitbit flex? Is a used on and the info I'll get from it worth $40?

    I lost the weight & maintained with a Fitbit Flex. By definition, TDEE (total daily energy expenditure) is the number of calories at which your weight will stabilize. So my Fitbit burn = TDEE.

    They retail for $100, so $40's a good deal. And Fitbit customer service is amazing. If your Flex breaks, they'll replace it—even though you bought it second hand.

    You can learn more in the Fitbit Users group: http://community.myfitnesspal.com/en/group/1290-fitbit-users

    I've had my Flex for two years. You need to charge it every 5–7 days. Make sure your friend gives you the charger.

    You shouldn't wear it swimming: http://help.fitbit.com/articles/en_US/Help_article/Can-I-swim-or-shower-with-my-tracker and it only tracks step-based activity. Log non-step exercise (like swimming or biking) in the Fitbit app.
    swimmermama wrote: »
    I'm eating close to 3000 calories and I'm a 5'8", 116 pounds, 35-year-old woman. She was curious about why my bmi is so low and suggested a Fitbit to see if I'm burning a ridiculous amount of calories during the day and to see about how much I should be eating.

    I think you mean your doctor wants to know why your TDEE is so high—your BMI is not low. If your Fitbit burn is less than 3,000, then a.) you're underestimating your food, b.) you have a metabolic disorder, or c.) ???.
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