In that case, your best bet may be to focus on the cardio, at least initially, according to a recent study by Duke University researchers. They took 234 overweight and obese adults and divided them into three groups. One group did a couple cardio sessions a week on a treadmill or elliptical machine, one did resistance training and the third did a combination of the two.

The study found the resistance training group gained weight, and while the combo exercise group lost weight, their results weren’t significantly different than the group that did cardio alone when it came to dropping fat mass and body mass. In fact, the study concluded that cardio alone is the most efficient and best exercise method at burning fat “when balancing time commitments against health benefits.”

These study results, published in the Journal of Applied Physiology, have caused quite a furor in the fitness community. Some trainers say resistance training builds lean, compact muscle, promotes overall health and plays an essential role in weight reduction. They therefore question the researchers’ conclusions.

And so I went on a personal quest for clarity and met up at the gym with fitness coach Gerard Burley, director of Coach G Fitness in D.C. We alternated between the elliptical machine and some walking lunges with weights. Burley says he did it to make a point: You need both.

He says when it comes to weight control, “The cardio takes it off, and the muscle and strength training keeps it off.”

Cardio, he explains, raises your metabolism and keeps your body mobile.

“The muscle and strength training is just going to keep your body toned and in a strong condition,” Burley says.

His advice for those short on time is to focus on what is known in the fitness world as “circuit training.”

That means getting your heart rate up while doing a series of exercises without any rest. For example, start with some pushups, maybe some squats or lunges, and then move on to a rowing machine or climb some stairs. Repeat.

“That way, we keep the intensity up,” Burley says, “and it keeps that cardiovascular portion working and strength training working at the same time.”

The key, he says, is to get some solid professional advice, and then develop a personalized exercise regimen — especially if you are among the chronically time-strapped.

“There is no cookie-cutter recipe,” he says.

We may not know the recipe, but we do know the ingredients: cardio and strength training.

You just have to find the mix that is right for you.

Editor’s Note: WTOP’s Paula Wolfson writes about the challenge of mixing family, work and fitness in our busy lives “on the run.”

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