An in-depth look at a recent study and why you did not get the whole story
One of the most debated fitness questions is whether cardio or strength training is better for weight loss. A few weeks ago, Duke University published a study that took on that very question. They came to the conclusion, cardio was king if you wanted to lose fat and that was the headline that was published online, in newspapers, and picked up by televisions stations.
And why question it? I mean, this is Duke… a well-respected university. Unfortunately, when it comes to fitness advice (and nutrition, and to some degree even medicine) you have to be a healthy skeptic.
A little over 200 hundred people were divided into three groups and performed resistance exercise, aerobic training or aerobics plus resistance training over an eight-month period. At the end of the study, the aerobic training group lost the most weight, weight went up slightly in the resistance training group, and the participants that did both resistance and aerobics dropped weight, but a little less than the aerobics-only group. Seems simple enough…
However, it’s more than just the number on the scale that you have to pay attention to. When you lose weight, you can lose water, glycogen (the storage form of glucose), muscle, and fat. Obviously, most people want to lose fat. Despite what the headlines would lead you to believe, it was the resistance plus aerobic training group that lost the most fat, not the aerobics group. And, even though the resistance group had a slight weight gain, it was their lean body mass that increased… not fat.
The aerobics group lost 3.8 pounds of body weight in 8 months. Of that, 3.6 pounds was fat. The resistance plus aerobics group lost 5.36 pounds of fat and gained 1.78 pounds of muscle. That’s a loss of 3.58 pounds. Not only is that extremely close to the total net loss of the aerobics-only group, the combo group lost more fat while gaining muscle. Muscle is a more metabolically active tissue. It actually helps you burn slightly more calories at rest than fat. Plus, two pounds of muscle looks a lot better on someone than two pounds of fat.
The other problem with this research was the study design. Participants did not do the same strength training exercises. They were just supervised while completing a full body workout. A chest press is actually much different than an incline chest press but it’s still working the chest. Doing your reps at a fast tempo works different muscle fibers than a “two up, two down count.” These are all items that were not controlled.
Plus, the researchers did not put restrictions on diet. Study subjects wrote in a food diary and self-reported their intake. It is well documented, people trying to recall what they ate 24 hours ago and estimate their portions is an unreliable method. Most people in the study probably over ate and under reported, explaining their lack of results but also showing that the outcome may have been much different if diet was kept in check. The study concluded that aerobics alone is the best for reducing fat mass. That is the line where the media pulled its headlines from. But, we have already seen that the aerobics plus resistance group loss of the most fat. There may have been a different number on the scale… but from both a physiological and aesthetic point of view, it was the combination group that fared best.
So what should you do if you have a limited amount of time to workout in your week? Participating in both forms of exercise is really best. This study really did not prove that you will lose more fat with just aerobics. There are so many other benefits to resistance training that for overall health, you should try to fit in both, even if it’s 20 minutes of aerobics and 15 minutes of strength training. When you start an exercise program, working out can feel like a chore, but you may find as you progress that you look forward to it and are willing to carve out more time.
If you are exercising for hours a day and your diet is not in check, you will not see results. This is a fact that people like to ignore. Until you know what you’re eating and how much, the number on the scale will never reflect what you want to see.
A final takeaway from this study is to always go to the source. Read the information yourself and ask questions. Usually there is not a one size fits all solution. People are motivated by different activities, have different genetic makeups, and respond differently to exercise. The best type of activity is one you can do (and enjoy) on a consistent basis.
If you have a story idea or to ask a question, email Michelle at email@example.com.
Michelle Fiscus and her husband own a personal training and nutrition business based in Frederick County and hold industry certifications and credentials.