In one research study, participants performed six days per week of cardio for one year results in an average of only 6 pounds (2.7 kg) of weight loss for men and women (McTiernan et al., 2008). Subjects aged 40 to 75 were instructed to do 60 minutes of aerobic exercise per day for 6 days per week for an entire year. You would think that with such a high volume of aerobic exercise, the subjects would have lost twenty or thirty pounds. Instead, weight loss was a disappointing 6 pounds (2.7 kg) for men and less than 5 pounds (2.2 kg) for women.
In contrast, recent research from Australia supports the notion that training with intervals only three times per week results in significant fat loss (Trapp et al., 2008). For this study, two groups of women trained three times per week for 15 weeks. One group performed 20 minutes of high-intensity interval training, while the other group performed 40 minutes of steady-state cardio. Only the interval training group had a significant reduction in fat stores.
The benefits of resistance training for building a better body can't be overlooked. Fortunately, a couple of recent studies in surprising populations show that resistance training can build lean mass and help with fat loss at the same time.
In one of the studies, 36 healthy men and women performed strength training three times per week for 12 weeks while consuming a 2000 calorie per day diet (Iglay et al., 2007). The workouts consisted of basic exercises that can be performed at any health club, including leg presses, chest presses, and seated rows. Each workout consisted of 3 sets per exercise and 8-12 repetitions per set.
While the average bodyweight of the men and women didn't change over the 12 week program, they did gain an average of four pounds of lean mass and lost over four pounds of fat. They gained muscle and lost fat at the same time, which most scientists will tell is impossible, but when beginners start a program, it does seem possible - at any age.
In addition, strength training also improved blood sugar control by 25% (as measured by an oral glucose tolerance test), helping to protect against diabetes. The researchers believed the gains in muscle mass contributed to improved blood sugar control.
This new research suggests three resistance training and three interval training workouts per week result in significant changes in body composition – with resistance training showing results even over the age of 60.
However, many people see this as, "If three workouts is good, then more must be better." That unfortunately leads to the biggest problem with increased fat loss training frequency: the risk of overuse injury.
A recent study performed in young women demonstrates the impact of training frequency on the risk of overuse injury (Josse, 2010). In this study, 20 young women trained with machine resistance training exercises five days per week for 12 weeks. Three subjects in the study reported overuse injury.
So what do the best three-day and six-day per week fat loss workout schedules look like?
Let's start with the three-day schedule. Together, the Purdue and Australian research studies suggest that three resistance training and three interval training workouts need to be completed. Fortunately, by choosing the right exercises, it's simple to identify a total body resistance training workout that can be completed in 20 minutes followed by interval training of 20 minutes. On the opposite end of the extreme is a six-day program. To make it easy, you could simply separate the resistance training and interval training sessions from one another, creating six 20-minute workouts.
By focusing on quality over quantity with interval training in less than three hours of training per week, you can gain muscle and lose fat at the same time, while staying injury-free. Of course, diet is more important than any exercise program, and nobody should reasonably expect any great results without proper nutrition. But if you combine the right training plan with a balanced diet, results should follow.