Why should I use a HRM and what kind is recommended?

get one with a chest strap. it tells you when you are in the correct range, helps you gauge your intensity and track calories burned. great investment, i use mine everyday!

A heart rate monitor with a chest strap takes into account age, gender and weight, then monitors your heart trate during exercise, sending the data to a watch that tracks your activity level and number of calories burned.

It's the most accurate way to know how many calories you've burned.

Polar is the best brand. What kind of Polar you get (cheap to $$$$$$) depends on what features you want. I have the most basic and it works fine for my needs.

HRM give you the most accurate calorie burns.....usually you need one with a chest strap, unless you are mainly walking or doing exercise that doesnt involve any bouncing around. The wrist only type arent very good if you are running or biking. I use a Timex Ironman Road Trainer with the chest strap (around $55 on amazon) it gives calories and min, average and max heart rates....it also tells you how long you stay in your target HR zone. I love it and found it way more accurate then what MFP gives you for calories.

I love my HRM =]]]

POLAR FT4 is awesome and has the best ratings go to amazon it's super cheap there!

Using a HRM during exercise is the most accurate measurement of calories you are burning during exercise.

That being said, I lost 60lbs and I've NEVER used a HRM. I used the machines at the gym and I did just fine. I don't think it is an absolute necessity (especially if you just can't work it into your budget). As long as you are working out and watching your calories - you'll be just fine. I'm proof that you don't need one to be successful (heck, I lost 55 of my 60lbs not even using this website, counting calories, etc... I simply ate less, ate better, watched my serving sizes and I worked out... I did just fine.

It will accurately measure calories burned during exercise. It's also a cheap and objective way way to measure the intensity of your exercise. The features you look for depend on which type of exercise you plan to do with it. Manufacturers make general ones and ones geared for different sports (i.e. running, cycling, etc...). If you work out with any kind of exercise bikes or treadmills, see if the machines integrate with a HRM, and if so, which brand. Polar is very popular, but cheaper, generic ones are out there that work great, too. You can go to Polar's website to compare various models to give you an idea of what is available.

Agree with other users, it depends on what you're using it for. 1 thing nobody has yet mentioned is that training in specific zones can actually help you to burn calories for efficiently while maintaining a healthy life style and also to reduce injury. You don't have to train in the highest HR zones to get the best results. I normally train in zone 2 for my age/sex which is about 150 while running. Though that sounds fairly low, when I'm running that equals about a 9 1/2 minute mile pace for me over a distance, say 4 miles. If you're interested in running/biking I would recommend the Garmin with GPS as you can actually start anywhere and if you want to go 4 miles that day, you don't have to map it out before hand, just turn the watch on and go, hit your halfway point (say 2 miles) and turn around and go back.

I personally use the Garmin 305, while it's like a laptop on your wrist, you get a ton of information that you can upload to your PC and look at your routes, calories burned, time and miles for each activity.

I also wear my HRM when I do Yoga with my wife, so I can put in the correct number of calories for that exercise. Depending on how hard you work in your exercise, you might burn more, or less, than this site is showing

But do you only use it when you workout or do you use it all day and see at the end how many calories you burned?

Only when you work out. Unless you have something like a BodyBugg, which is designed to track calories all day.

I use Polar ft60 ..the best investment of my life!!!