How important is heart rate for calories burned? ... and a couple of other questions/problems!

[Fuzzybojo]

I've decided I need to get in shape, lose some weight and I'm super motivated, but I've noticed a couple of things that I'd like some feedback on.

My gym schedule is Mon - Fri. Each day is 40 mins of exercise bike and I'm slowly working weights in. With regards to the weights, I'm just doing it sporadically until the DOMS is less severe. I have hardly any now,  which is great, so I'm planning on doing weights Mon, Wed and Fri.

I started the gym on the 26th of August, attempted HIIT on the exercise bike, realised I was super unfit after just a single sprint, then proceeded to keep a steady pace for the remainder of the 40 mins. Tuesday and Wednesday I decided to try HIIT again, but instead of going flat out, I'd just opt for an increased pace during the sprint part. My HIIT is a follows: 7 km/h recovery pace for 60 seconds, 12 km/h intense pace for 30 seconds, do it 5 times and then wait 2 mins before doing it all again. I did it 3 times in total.

Thursday I thought I'd try a steady pace of 10km/h for the full 40 mins and see what it compared to my version of HIIT, it was not as effective. Friday was back to HIIT. Here's the break down of the week, each day except Thursday was using the HIIT plan I detailed above.

Mon - 151 avg bpm, 38 mins cardio, 2 mins peak and 595 calories burnt.

Tues - 146 avg bpm, 37 min cardio, 4 mins fat burn and 569 calories burnt.

Wed - 146 avg bpm, 41 mins cardio and 572 calories burnt.

Thurs - 125 avg bpm, 1 min cardio, 40 mins fat burn and 412 calories burnt.

Fri - 145 avg bpm, 40 mins cardio and 548 calories burnt.

I rested Saturday and Sunday. Yesterday I did weights and then the exercise bike, using the same HIIT plan.

138 avg bpm, 38 mins cardio and 2 mins fat burn and 498 calories burnt.

This leads us to the problem, which is today. I only did the exercise bike today, but after seeing yesterday's results I decided to put in more effort. I did over 4 sets of HIIT today, each at a faster pace. 8km/h+ recovery pace and 13km/h+ intense pace. My stats were as follows:

128 avg bpm, 9 mins cardio, 31 mins fat burn and 409 calories burnt.

This is the worst day yet. I don't understand how the numbers can have dropped so much over the course of the week. Today I increased my effort, but I have less to show for it. Surely that can't be an increase of fitness in such a short time span? Is the heart rate really that important to the amount of calories burnt?

My other question is, I'm doing a 1000 calorie deficit and have been as much as 500 more than the 1000 deficit every day, Mon - Fri, Sat and Sun were rest days and I was just on the 1000 deficit. I weighed myself Monday and again on Saturday and I lost no weight. I have been meticulously weighing everything I eat, as I wanted to see what my diet was like prior to adjusting it. I feel like I eat pretty well and that feeling was justified by how easily I maintained a 1000 calorie deficit over the week. When I saw I lost no weight, it was a little disheartening to be honest. What's up with that?

I'd really appreciate any help or insight on the above. Many thanks.

[JohnnyRow]

A few thoughts without going through your numbers in detail:

Do not do high intensity on consecutive days.  Your body needs at least a day in between to recover.  Twice a week is probably plenty if you're not used to it, 3 times a week at most.  Still exercise the other days but without the intensity.

Getting fit is not a quick process.  Don't pay too much attention to the numbers, calories and weight.  Just keeping it up is much more important.