Question for all you chicks! I've been working out with a personal trainer for almost a year. He has begun to increase my workouts (which is great), but I'm noticing that the amount of calories I'm burning isn't increasing.

Now, my trainer said that this is because my body has become more efficient, so I'm burning more calories throughout the day, not just during workouts. Now, I used to burn 700-800 calories, but now am burning 450-550 calories in the same amount of time.

Has anyone else/encountered this? I use my heart rate monitor religiously to see how many calories I burn. So, just curious if anyone is experiencing the same thing? Don't get me wrong, I'm still losing weight, etc. I was just curious.

My metabolism has also skyrocketed, so I'm eating more throughout the day, but only fruits/veggies (no snacky foods!)

ABsolutely, and its *not* necesarily a good thing (unless you consider not beling able to eat more food a good thing!) I guess itd also be good if you were trying to gain....
So basically, youve possibly been trying to lose fat for at least a year? In a caloric deficit? Mostly?... Working out/exercising hard and regularly?

Well, your body has become efficient at operating off of fewer calories. Plain and simple. Now, as far as ENDURANCE is concerned, i supposed this is a good thing... efficiency, that is. But its definitely not ideal or helpful for fat loss! For example, i trained for and completed 2 marathons off of approx 1200 cals a day. I didnt know any better. Well, guess what? I stopped training for marathons, and suddenly 1200 a day is a surplus! AM i making sense?
The metabolic adaptation is kind of a given for long term dieters. However, you can help reverse it alittle by starting to institute things like re-feeds, and also by taking a de-loading/rest period in your training.... things like like...

This may be a "duh" statement, but the less you weigh, the fewer calories you burn.
So, if you've lost weight in the last year (and it appears that you have-congrats), your calorie burn will go down also.
How are you measuring your calories burned? That could be a factor also.

Also, the more you do an activity, the more your body adapts to it. That means it will require less effort (lower heartrate, lower calorie burn) to accomplish the same things. That's why it's so important to change up your exercise every few weeks. Looks like your trainer is doing that, but you may want to mention that what he's doing feels easier to you than when you started, and that you want to step it up a bit to get your calorie burn back into the high levels you were hitting before.