Short periods of fasting (less than 36 hours) do not slow your metabolism. Studies show the exact opposite. Plus, intermittent fasting is associated with an increase in HGH (human growth hormone), sex hormones, and stability in blood glucose and insulin levels, all of which are optimal for speeding your metabolism and burning fat. And as long as a person is eating an adequate amount of fat and protein during their feeding hours, starvation mode will never come close to being an issue.
I highly recommend everyone interested in the subject of cardio to watch this. It succinctly highlights the benefits of high-intensity, as opposed to low-intensity, cardio exercise. https://www.youtube.com/watch?v=1aMrom1sYSs"]Dr. Mercola's Presentation on High Intensity Exercise (Part 1 of 2) - YouTube https://www.youtube.com/watch?v=puNVuNINRQ4"]Dr. Mercola's Presentation on High Intensity Exercise (Part 2 of 2) - YouTube And these guys crack me up, but sometimes they give good advice, too. https://www.youtube.com/watch?v=CsAl3Z-NEhc"]High Intensity Interval Training Cardio - YouTube
Set realistic goals, especially starting out. Only run if you enjoy it, otherwise it will become a hated chore. I love to run, but when people at work ask my advice, I tell them to swim. It is easier on the joints and lower back, especially for big people. good luck, JKHolman