How do I determine my target heart rate?

I've been going to the gym now for three months regularly (sporatically before that) and have gradually been working on increasing calorie burn during my 40 minute work-out.  I'm up to 358 calories and working on my next goal which is 400 calories and was figuring that I was making decent progress.  Now it seems that I've been doing this all wrong for weight loss by going over my target heart rate.  Can anyone help me clear up this heart rate thing?  I really want to lose this weight.  I'm tired of feeling like I look like the Goodyear Blimp.

Target hear rate... for what?  If you were running a marathon you shouldn't be shooting for the same heart rate as if you were running a sprint.

For weight loss.

If you're going to shoot for a specific heart rate, then the one that causes you to burn the most calories will result in the most weight loss.

The most efficient form of cardio to burn fat is interval training (where you go fast, then slow, then fast...)

That's what I've been doing lately.  I walk for 5 mins, run for 3, walk for 5...over a 40 minute work-out.  My heart rate gets pretty high during the sprints though.  I was just trying to make sure that I wasn't defeating the purpose by getting my heart rate too high.  Thanks!

Burning calories is what is important for weightloss.  Whether those calories are coming from fat or glycogen is not important in the long run.  So working out at higher intensity levels and burning the most calories per minute that you can burn will have the greatest impact on long term weightloss.  For more about my opinions on the subject check out my journal.

Thanks!  That's what I thought.  I just got confused when they were discussing aerobic vs anaerobic based on heart rate.  I did test to see if I could talk while I was running and it was definitely possible for me to do so.  The other people at the gym probably thought I was carzy though!  LOL!

I also started looking into this a few weeks ago and bought myself a heart rate monitor.  At first I thought that I should be working in 'the fat burning zone' as the information implied that I burnt more fat off in this zone. But... when I looked into it more I found that this is misleading because when you go into the higher zone you burn more calories and although the % of fat burned is lower because you are burning more calories you are likely to be burning just as much fat off as in the lower zone, if not more, and also more calories.  It is confusing because it is based on % of fat burned and I found that the differences in % were not very big from zone to zone.  So...stick to working as intensively as you can without getting too out of breath for the best weightloss.

As an example (not using correct % because I can't remember them! - but just to get your head around the number thing!)

if you burn 100 cals in one zone and 40% are from fat burning then 40 cals are 'fat cals' burnt,

if you burn 120 cals in a higher zone but 35% are from fat burning then 42 cals are 'fat cals'.

so although the fat burning % is lower because more cals are burnt by working in a highter zone more cals are 'fat cals'.

So...stick to working as intensively as you can without getting too out of breath for the best weightloss.

Good Luck!!