I'm not an expert but I was told to get a certain brand and at least a certain level so I did. It cost oodles. Like, over $100. The strap can go in the washer but not the dryer. Guess what happened? Yup, strap got dried. It doesn't work very well now. I'd need a new strap to get it working properly.
So I started doing a different workout and the guy whose program it is answers questions. I asked something about the HRM and he scoffed. I was a bit taken aback at the time but now I get it.
His motto is, "You can't out-train a bad diet." The way I transformed was by ditching the HRM, cutting calories to a deficit, and cutting way back on exercise. I used to shoot for 3000-4000 calories/week and I lost about 1/2 pound every month or two. It just wasn't happening. When I started counting calories, I lost an average of a pound a week for 12 weeks.
Also, I stopped logging workout calories into my calorie tracking. There is no sense eating more to make up for a workout.
I am not sure I'll ever bother with my HRM again. Um, it's for sale, I guess! If you wanna go get a strap! LOL! That's about $15 or so. Not much of a sales pitch, eh? I don't really wanna sell it to you!