Your Questions Answered By Tom Venuto
Question: I just read an article in a bodybuilding magazine that said all you need to lose fat is three days a week on a cardio machine for twenty minutes. It said that low intensity, long duration cardio workouts are not the best way to lose fat and that a high intensity twenty-minute workout is more efficient. Is this true? I don’t have a lot of time to work out so it would be great if I could get my cardio done in only twenty minutes.
Answer: Getting in great shape by spending only twenty minutes a day, three days a week sounds great. There are plenty of “guru’s” out there claiming that “Eight minutes a day is all it takes” or “Just twenty minutes a day is the solution,” but when things sound too good to be true, they usually are. If your goal is better health and a decent level of cardiovascular fitness, then three days of cardio a week for 20 minutes IS all you need. However, if your goal is to lose a lot of body fat as quickly as possible, then you’re probably going to need a lot more than 20 minutes (unless you’re one of those genetically blessed few with a fast metabolism who loses fat easily.) I have never seen anyone lose a lot of fat by doing just three days a week of cardio. On the other hand, I have never seen anyone do six days a week of cardio for 45 minutes and NOT lose a lot of body fat.
It’s true that moderate to high intensity cardio such as interval training is more effective than low intensity cardio: The higher the intensity, the more calories you burn. The problem is that you can only burn so many calories in 20 minutes. The more calories you burn in a one-week period, the more fat you’ll lose. If you do a high intensity interval workout 3 times a week for 20 minutes on a Stairmaster or bike at a high intensity, you might burn about 400 calories. That’s a lot of calories for a twenty-minute workout. But it only adds up to 1200 total calories burned in one week. If you doubled your time to 40 minutes and you did six days per week at a moderate intensity, you would burn about 600 calories per workout. Do that 6 times per week and that’s a total of 3600 calories in a week – three times as much as the high intensity interval workout! Combine the cardio with a 500-calorie per day deficit and that’s another 3500 calories for a total deficit of 7100 calories per week. There are 3500 calories in a pound of fat, so that’s two pounds of fat you’d lose in one week!
What I would suggest is that you approach your cardio training in cycles depending on what your goals are. If you just want to maintain your current level of body fat and stay healthy, I’d recommend 20-30 minutes of aerobic activity 3 – 4 times per week. If your goal is maximum fat loss, then I’d recommend 30-60 minutes 5-7 days per week. Once you reach your desired percentage of body fat, then you could drop down to just 3 – 4 days a week for 20 minutes to maintain your low body fat level. I agree that low intensity cardio is not the best way to lose fat. You should always keep your intensity moderate to high, provided that you can maintain it for the desired duration. If you reach 45-60 minutes 6 times per week and you’re still not losing fat, then the problem is definitely your diet, not your workout program.
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