Usually, a 7 minute workout can't much for you, but if you have some serious compound movements in it then, you may see some benefit. An example would be.
1 minute of burpees + squat an press - What you do is, put a pair of DBs infront of you, do a burpee but instead on putting your hands on the floor, get hold of the DB and when you get back up, bring the DB with you upto your shoulders, do a squat and on your way up, push the weights to do a shoulder press.
30 seconds of any compound (i.e. upper + lower) abs exercise
1 minute of burpees + squat an press
30 seconds of any compound obliques exercise
1 minute of burpees + squat an press
30 seconds of any compound (i.e. upper + lower) abs exercise
1 minute of burpees + squat an press
30 seconds of any compound obliques exercise
1 minute jump rope
If you can do this, you will SURELY lose weight, but this is tough and make sure you are warmed up before hand. If you have 10 MINUTES and you can complete this for those 10 minutes...FAT will not be an issue for you in just a few weeks/months