HEY SAM:  I do cardio to burn fat. I know my body adjusts to the type of cardio. Do I have to keep changing the type of cardio I’m doing to get the full effect? —Arsh, Los Angeles

You’re right. The body adjusts very quickly to exercise. Interval training (or “high intensity interval training,” sometimes referred to as “HIIT”) is very effective at reducing body fat.   If you’ve stopped seeing the results you want, then it’s time to mix up the program.

One way to do this is to alternate your longer-endurance cardio days with high intensity interval training.

Here’s how a typical week might look:

Let’s say you do a few miles on the elliptical machine at a high resistance on Monday.
On Tuesday, you could do HIIT intervals.
Take Wednesday off.
Do a long slow (but steady) uphill climb on Thursday, and intervals again on Friday.
Use the weekend as an opportunity to cross train (play a sport, go skiing, walk outdoors, etc) and/or take one of your weekend days off.

An interesting fact about intervals: they’re super effective at getting rid of body fat, but scientists haven’t figured out yet which length of intervals (short, medium, or long) work best. So, cover your bases and mix up the length of the intervals themselves, too.