FitBit or Polar HRM ?

A FitBit is a glorified pedometer so if that's all you want then it's great. For real cardio workouts a HRM is going to be far more accurate. It's easy enough to figure out your basic calorie needs with out a FitBit and just add you actual workouts with a good HRM.

I have both a Jawbone UP (which is like a FitBit) and a Polar FT7. I use the HRM anytime I workout so I know where I am at with my burned calories and HR. The UP is great at letting me know where I am with my daily TDEE. Along with the other benefits of the sleep function, etc. it's a great tool to have. I was using a bunch of calculators to figure out my TDEE and now I am able to know exactly what my TDEE is without having to guess. The calculators were off by a few hundred, so now I know where I can be with my nutrition and know my numbers are legit.

I have both so it is hard to choose. I bought the Fitbit first (and it is great) but the HRM has been a lifesaver for calculating cardio calories burned since MFP is too high. I guess if I could only choose one, it would be the Polar (FT 7) but I would strongly suggest buying both and you can get both for around $200-$250.

HRMs are designed to be worn during workouts to report to you current heart rate. They've since "graduated" to forcing an algorithm that supposedly calculates calorie burn using heart rate as the sole variable. This is pretty awful, for a number of reasons. Even at a baseline, heart rate corresponds to calorie burn only as a function of VO2max, or cardiovascular efficiency. The problem is that VO2max varies wildly from person to person, and changes significantly as you become more fit. The HRM companies just compute a pretty random average/guess. The result is that people generally end up with laughably wrong calorie "burns" calculated by their HRMs.

On top of all that, heart rate is affected by a number of factors that have nothing whatsoever to do with how many calories you're burning. If you wore one then drank a Red Bull and walked through a really bad part of town at night after you found your wife sleeping with another man, it might tell you that you're burning 1000 calories an hour even though you're strolling casually at 3 mph.

On the other hand, Fitbits measure the actual movement of your body core using a 3-axis accelerometer. From this movement, it's possible to actually calculate the amount of energy required to move your body mass in that way. They're also designed to be worn 24/7 instead of just during workouts, so they capture all the "hidden" calories throughout the day.

Long story short, Fitbits are little portable TDEE calculators. You just keep it on your waist or in your pocket and it tells you the total number of calories your body has burned that day. In my experience, they are extremely accurate. I know a number of people who use them, including myself.

I use a combination of MFP, Fitbit, and Trendweight. Every day I eat about 400 calories less than my Fitbit says I've burned. As a result, over the past 3 months I've lost 9 pounds, which is almost exactly what is predicted by the calorie deficit calculated by Fitbit. I've seen these results repeated in several different people.

Long story short, Fitbit devices are very accurate and really help simplify everything. You just eat a few hundred calories less than the Fitbit says you've burned every day. The end.

FitBit is nice for goal setting and long-term wear (it really is just a fancy pedometer). I just purchased a HRM FT7 for $70.00 off of Amazon and I LOVE it! I feel confident in it's ability to accurately estimate calories burned and HR.

I have both a Jawbone UP (which is like a FitBit) and a Polar FT7. I use the HRM anytime I workout so I know where I am at with my burned calories and HR. The UP is great at letting me know where I am with my daily TDEE. Along with the other benefits of the sleep function, etc. it's a great tool to have. I was using a bunch of calculators to figure out my TDEE and now I am able to know exactly what my TDEE is without having to guess. The calculators were off by a few hundred, so now I know where I can be with my nutrition and know my numbers are legit.

I really like my Jawbone UP as well. The interface is great and the sleep tracker is quite informative. I like that it's waterproof also so I can wear it swimming or in the shower. Good luck!