Kinect Sports

To get this you just need to beat the pizza and soda in the same session. In other words once started do not turn off your Xbox.

Tips:
You can get calories before and after an event finishes
It works on movement so wave your arms and move about a lot the more you move the more you burn.
Wave as much as possible and don't worry too much about the game itself
run from left to right while waving no matter what the event this helps
Some games you can burn calories without starting the game, I would do this a little to boost your score but not too long as you still have to wait
Having a second player take over helps on the harder foods.

If you have beaten the target and the timer goes over, don't worry it normally allows one final game before finishing.

If you have anything to add, leave a comment and I'll improve this solution.

Thanks to GlorixJim for these further tips:
- you can calculate the average kcal/min you need to beat your opponent. The running games will give you the opportunity to get way past that number (20-25 kcal/min), while the light and medium stuff sometimes nets you only 3-7 kcal/min. To beat the pizza, you must average almost 8 kcal/min.
- The second player is a great way, but you can also use your GuideButton to pause the game- time DOES stop.
- I think you will burn calories after the game, regardless of moving or waving your arms.
- for some games, waving your arms (and running left/right) seriously increases your kcal/min average.
Like the volleybal related games, you score more points/kcals running left and right, waving your arms then really trying to hit/dodge the fruit. The score while standing still and catching the fruit with your feet/hands/head is a poor 0.03 kcal/second!

Best Solution if you still struggle to make it in time!

I do recommend using a big towel, it is easy that way.
Move sideways and wave the towel. Not really necessary to move sideways so much but I do think it speeds it up a bit. What really speeds it up is if you wave harder with the towel, I mean wafe faster. Make it so it reach the floor and just wave very fast to increase the calories.

When you randomly get the table tennis were you can score points between 1,2,3. Just dont serve and stand still with the towel in your hand. (More safer way is to actually not choose left or right hand as you can make calories run from there. This way you wont accidently serve).

You can reach your target here without ending the game as the timer never starts until you serve but your calories goes up.

I also noticed it should also work with one of the bowling events. (Not the one were they charge at you).

Remember you need to finish both the events in one session!

And you need to finish both events before the achievement will unlock.

IMPORTANT NOTE: If you do this trick, the in game timer will be wrong and you will go overtime and have to play many extra events so you dont really need to get all calories in one go using this trick as you for example would still have to do all that time after. I had to play up to 36 minutes vs the pizza as I did use this trick to catch up a bit.