220 lbs - burning 650 cal in 40 min on an elliptical?

Can you go a bit more into detail?

I personally train at about level 5 resistance. I do 20 seconds (15speed) as hard as I can then slow down for 1 minute (5-6 speed) .. repeat the cycle for 10 sets
(5min pre/post) to warm up/cool down

After about 30min I'm at 400 cals, I'm 5'11 currently at 225lbs

I use the elliptical in my gym. I set it on fat burn mode and it changes the resistance for me based on my heart rate. I usually end up burning around 190-200 calories for 30 minutes. 650 seems like an over estimation to me.

Wt: 117
Age:36

HRM is the way to go, I know what the machine and MFP say is usually above what my HRM reports for the bikes and elliptical trainers at the gym, usually by around 70-100cal

You could always buy yourself a HRM, in my case i always take away like 100 calories from whatever the eliptical says

I personally don't eat back my calories but that's just personal preference. I plan my days ahead of time so my meals already have those calories added into them..

I use a HRM and find the machine always is a much higher number than my HRM. Usually 20-30% more.

This is why I bought a heart rate monitor, and because there was such a discrepancy between my Iphone pedometer and MFP and the treadmill at the gym. It turns out the pedometer was under and MFP/gym machines were WAY inflated. In fact, after my run today, the treadmill read almost 200 calories more than my heart rate monitor.

Just for a comparison. I weight 200 pounds. I set the elliptical on the highest setting for height. I set the resistance at 14 out of 20. After 20 minutes, I move down to 12. In 40 minutes I burn between 500 and 550 calories. This is with an average heart rate of 140s.

I run 5 miles in 41 minutes. It is usually about 750 calories. My heart rate average will be in the 160s.

I've messed around quit a bit and the polar ft7, the machine reading and My fitness pal. They are usually within 5%.

I'm really running all out for that reading. So take all those factors into consideration. Sometimes I use MapMyrun, it shows the calories quite a bit higher than the other 3 readings so I ignore the MapMyRun readings.

So my guess would be 450 for you, but that's just a guess without knowing your effort, fitness level, etc, just your weight with a guess.

I'm 5'9" and about 214 lbs and MFP estimates that I burn about 430 cal in 30 min on the elliptical.
I personally eat back all of my exercise calories most days, and am losing at least 2 lbs a week currently.
I would try to eat what they tell you, and then only adjust down if you have to. The more you can eat, the happier you will be, and the less you will damage your metabolism (see: metabolic adaptation). As you lose, you will have to eat less to continue seeing results, so why not start with as many calories as possible?

Good luck!

I use the Polar FT40 Heart Rate monitor, and find it to be far more accurate than any machine or generic estimates. If you get one, you'll enter your info (height, wt, typical activity level, gender) and, for me anyway, gain a little extra motivation as you can switch the watch to display your current calories burned. Sometimes if I know I'll be having dinner out, or I baked a yummy dessert, then I'll stay on the machine a little longer than I would have because I haven't hit my calorie goal yet.
The accuracy is so nice, but the feature I like even more is that the machines in my gym (and most gyms) have a "Heart Rate" setting, which will pick up the signals from your HR monitor and automatically adjust the machine settings to make sure you maintain the target HR you choose at the start of your session. For example, on the stairmaster I'll set it to maintain a HR of 152bpm for 30 minutes. In the beginning it goes faster because my HR isn't high yet. Then as my HR climbs, it will slow a bit or speed up depending on what my heart does.
*Note: Even doing this, you still need to go with what the Polar watch tells you for calories, not the machine! They are usually vastly different.