You're asking and I'm answering . . .
I've been reading that warmups on treadmills are important to lose weight; why is warming up and cooling down important?
— Confused Cardio Fan
Thanks for the question. I'm happy to say that your sources are correct, both warming up and cooling down are very important. To find out why just read more.
Even though they may seem totally unnecessary, a warmup and cooldown are crucial to your workout. It doesn't take much, but just five minutes of a cardio warmup is enough to get your blood flowing. Not only will your muscles work more as a result, but a warmup also decreases your body's perceived exertion of how hard you are working (things feel easier), and it helps prevent injuries. Plus, your heart is a muscle and it needs to be eased into exercise too.
A five-minute cooldown cools (hence the name) your body temperature and allows the body to remove the waste products from muscles that were worked, prevents delayed onset muscle soreness and blood pooling (which could lead to fainting), and decreases the adrenaline in your blood stream (relaxes you).
In terms of weight loss, properly starting and ending a workout decreases the likelihood that you'll get injured, which increases the likelihood that you'll keep at it each day. Plus, an extra 10 minutes of moving around means more calories burned and, as we all know by now, every little bit counts.