Like you, I used to think that the key to losing weight was hours and hours of cardio. When I was merely pudgy I thought that I was simply too lazy to put in the hours upon hours of mind-numbing time on the bike, treadmill or elliptical machine at the gym.
After being made fun of one too many times for my love handles and man-boobs, I'd had enough and decided to get serious about getting fit. (Unlike many in the fitness industry I was not born fit, but fat.) I asked a bodybuilder for advice, and he told me that the key to leaving my doughy figure behind was simple do cardio twice a day.
His advice wasn't what I wanted to hear since I didn't have much free time, but I was desperate to "burn off' my spare tire, so I sucked it up and suffered through. The results were surprising. Not surprising in a good way, but in a bad way I went from a doughy 220 pounds to an obese 240 pounds. (I'm only 5-foot, 10-inches). Getting fatter by spending all of my free time at the gym was not what I had in mind.
My experience is actually far from unique, and we've had research since 1989 saying that hours and hours of cardio does not work for weight (fat) loss.
In 1989 Danish researchers had obese men and women spend 18 months training for a marathon. After a year and a half the men had shed just 5 pounds, and the women had lost no pounds whatsoever.
In 2008 Australian researchers tested a "realistic" cardio program 3 days a week for 40 minutes, and the women in this study actually gained a pound of fat over the 15 week study.
This year American researchers looked at the past 10 years of research on "cardio" (technically aerobic exercise) and found, "isolated aerobic exercise is not an effective weight loss therapy."
The idea that aerobic exercise (like long distance running) turns overweight people into thin people comes from the observation that elite distance runners are very thin people. This is as scientific as the idea that playing basketball can turn short people into tall people, since elite basketball players are very tall people. (If only that were true. I'd be 6 feet tall!)
There is, however, very good news, we've also know since at least 1989 that both metabolic resistance training (MRT) and high intensity interval training (HIIT) both actually work well for weight loss. Even better, these kinds of exercise are safer, less boring and take less time.
MRT is resistance work designed to change your metabolism after the workout. MRT pushes your body to access more of its own fat for 1-2 days to come the gift that keeps on giving.
HIIT also has a positive impact on your metabolism after the workout (unlike traditional cardio), but less than MRT does.
HIIT would involve a warm up, followed by a 30 second all-out sprint on a bike, followed by peddling slowly for 60 seconds, and then repeating that pattern nine times. This would be a great place to start for your first month. However, after the first month you'd want some professional guidance on a long-term, systematic program so you keep making progress instead of hitting a plateau.
And example of MRT would be doing compound movements like squats and push-ups to get as many of the muscles in your body working