A recent study from Duke University comparing aerobic versus weight training to see which is better for fat loss was one of the most publicized studies of the year. My in-box was bursting with emails from Burn the Fat readers sending me links from news websites, and asking me, “What do you think of this Tom? Should I stop lifting weights and focus on aerobics until I get the fat off?” I think the researchers missed the mark when they concluded that “Aerobic exercise is better” … Read on to find out why and see what the top trainers, best bodybuilders and hottest fitness models in the world really say is the best way to burn fat the fastest…
Duke’s press release headline said:
“Aerobic exercise trumps resistance training for weight and fat loss.”
The New York Daily News picked up the story and published this headline:
“Aerobic training may burn more fat than a combination of weights and aerobics.”
Medical News Today published this one:
“Aerobic exercise best way to burn fat, not weights.”
These were the messages getting passed all around the Internet, usually by people who clicked a “retweet” or “share” button and didn’t even read the entire research paper. But what did the study really tell us?
What’s better for fat loss: aerobics, weight training or both?
After reading the news blurbs, you might be led to believe that if your goal is fat loss, you should focus on aerobics like running or cycling, not resistance training. Although aerobics (aka cardio) is a proven way to help burn fat, I believe that saying, “Aerobics alone is best” is sending the wrong message and taking us backwards into the dark ages of fitness.
After decades of being ignored or even shunned by the health and medical communities, and after an era of aerobics dominating the fitness scene, weight training finally got its due respect as a key element in a total fitness program, including for fat loss. In the strength and conditioning community, we were thrilled when institutions like the American College of Sports Medicine (ACSM) finally added resistance training to their position statements.
We want to see that positive message continue to be spread widely to the public. Unfortunately, we still have researchers and the media running you around in circles: First recommending aerobic training only, then it was aerobics training plus resistance training, and now they’re saying it’s just aerobics again.
Confused? Trust me, they had it right at aerobics plus resistance training, especially when you look at the big picture and not just the body fat percentage alone. Strength training is the unsung hero in achieving total health and fitness.
Of course, the media loves stories like these because there is nothing better for getting attention than controversy and contradiction. While it’s important to keep an eye on new research and balance those academic findings with real world results, in this case, I don’t agree with all the conclusions of the study authors.
The study, known as STRIDE-AT/RT (Studies of a Targeted Risk Reduction Intervention Through Defined Exercise – Aerobic and Resistance Training) was conducted at Duke University in North Carolina. In this randomized controlled trial, 211 test subjects were assigned to one of three groups:
1. Resistance training
2. Aerobic training, or
3. Aerobic plus resistance training
Aerobic training included treadmill, elliptical trainers or bicycle equivalent to 12 miles per week at 65% – 80% of peak VO2. Resistance training included 3 days per week of weight training exercises for 3 sets of 8-12 reps. There was a ramp-up period with 1-2 sets during the first month. Exercises were not specified, but they covered all major muscle groups and workouts were supervised or confirmed.
These were the general findings:
- All three groups lost fat mass and body fat percentage
- The aerobic training group lost more total body mass (body weight) than the other two groups
- The resistance training group increased lean body mass more than the other two groups (confirmed by body composition and thigh circumference measurements)
- The resistance training group did not reduce body mass. Weight went up slightly. (However, body fat went down slightly. The lack of decrease in scale weight was due to an increase in lean mass).
- The resistance training plus aerobic training group decreased body fat percentage and fat mass more than the other two groups.
Looking at these results, it actually appears as though the resistance training plus aerobic training group had the best fat loss results: Similar total body weight loss as the aerobic only group, but greater loss in body fat percentage and greater loss in body fat mass.
The researchers seem to discount this fact by qualifying their “aerobics is best” conclusion based on time efficiency or what they believed was the most important outcome for health benefits.
However, the truth is – and even Duke’s own press release didn’t mention this – when you read the full research paper and analyze the actual change scores, NONE of the results of ANY group were very impressive…
These were the specific findings, by the numbers:
- The aerobics only group (deemed “most successful”), lost a mere 3.8 pounds of body weight and 3.6 pounds of fat in 8 months.
- The resistance training group gained 2.3 pounds of lean body mass and lost only .57 pounds of fat mass.
- The aerobic plus resistance group lost 5.36 pounds of fat mass and gained 1.78 pounds of lean body mass. That looks like the winner to me for overall body composition improvement, but even that is nothing to get excited about.
Suppose the press release had said, “Study shows that aerobic training produces almost 4 pounds of fat loss in 8 months,” or “Aerobic training burns three-tenths of a pound more than aerobics plus resistance training.” Do you think there would have been so many headlines? Well, those are the numbers! Why was there any buzz or hoopla about these study results at all?
With proper program design, shouldn’t you be able to lose a lot more than 4 pounds in 8 months? In fact, since this study was conducted on overweight and obese subjects, wouldn’t you have expected more weight loss than average? (Isn’t it common to see an obese person lose 4 pounds of bodyweight in the first week?) Regardless of your starting point, if your goal is fat loss, would you be happy with less than 4 pounds for 8 months of effort?
Why the poor results? There are many possible explanations.
For one, we don’t have that many specifics about the program design, progression or energy expended from the weight training workouts. The exercises may have been all low-energy expenditure machine movements like leg extensions. There may have been poor application of progression and periodiziation. And in the aerobic group, the volume and/or intensity of training may may not have been enough.
Diet: The crucial (missing?) element
More than likely, one of the biggest reasons for less fat loss and weight loss than you’d want or expect in 8 months is lack of tight control over the subject’s diets.
A cursory skimming of the study suggests that they did have the subjects report their food intake. However, a closer look at the full text shows it was done with 3-day food records and 24-hour food recalls. It’s a well-proven fact that self-reporting of food intake by research subjects is horribly unreliable. A lack of weight loss can very often be chalked up to more calories being eaten than were reported. No exercise program – weights or aerobics or both – works well without proper nutrition.
Granted, studies with true control for food intake are difficult to perform, especially for extended periods of time. But fortunately, we don’t need more studies to understand what happened in this case.
We already know that the key to fat loss is the calorie deficit, not aerobic training per se and not resistance training per se. It’s possible to create a calorie deficit with ANY type of training program – cardio or weights. However, is it possible to do aerobics and not have a deficit? Of course. Is it possible to lift weights and not have a deficit? Of course! Is it possible out-eat ANY training program? Of course.
The biggest question in my mind is why the researchers drew the conclusions they did: Here’s what they said, word for word:
“If increasing strength and muscle mass is the goal, a program including resistance training is required… (So far so good… we’re still cool)…
“However, balancing time commitments against health benefits accrued, it appears that aerobic training alone is the optimal mode of exercise for reducing fat mass.” (Based on this data? Really? Okay, now we have a difference in opinion).
I believe, and actually the absolute data seems to confirm it, that resistance training plus aerobic training together trumps either type of training by itself. The study authors themselves point out that each type of training has its own set of benefits. But apparently, factoring in the increased time commitment of doing both, they judged in favor of aerobics only as the preferred option for decreasing fat mass.
That raises yet another question: Should losing weight or even just losing fat be your only goal or your primary focus?
Weight training: Key to the world’s fittest, leanest, healthiest and most attractive bodies?
I’m not sure what is the background of the authors of this study. Some researchers have done mostly academic work, others have a practical background in strength and conditioning. Here’s mine: I come from the trenches of a personal training and competitive bodybuilding career, with a degree in exercise science and I’ve held many personal trainer and strength coach certifications. So, I’m definitely partial to weight lifting and muscle-building as the best tool for transforming the body. However, I’m not alone in my “bias”…
I’ve been surrounded by other professionals in the fitness trenches my entire life and I don’t know a trainer worth his salt (one who actually transforms other people’s bodies every day) who agrees that aerobic training should be the sole focus of a fat loss program or even that fat loss should be the sole focus of a health and fitness program.
Mind you, I’m not knocking aerobics – not at all. I’m a big fan of including cardio as one part of the mix. That’s my whole point: It’s practically common knowledge among experienced trainers that better body composition is produced from combining weight training with cardio training.
There is a group of strength coaches and diet gurus today who insist that weight training combined with very strict diet is sufficient to produce fat loss. Surely that is true, but isn’t it also true that most people seem to get better results when adding cardio on top of weight training? Aren’t there “endomorph” body types where weight training alone doesn’t seem to produce the fat loss/ weight loss results wanted at the rate they are wanted? Didn’t this study seem to bear that out? I can side with the researchers as far as that goes: Weight training alone may not be optimal for fat loss for most people. Put cardio into the mix.
I suppose a good question is how do we prioritize and allocate our time to each activity? Following the same rationale as the researchers – balancing time commitments with health benefits – shouldn’t weight training be higher in the hierarchy than aerobics? Given the huge benefit list for weight training (which includes better health), shouldn’t an ideal program start with weight training plus nutrition as the core elements and then add cardio in to increase fat loss and conditioning as needed? That’s how I see it.
For those with real time commitment issues, it’s comforting to know that fat loss really can be achieved just by dialing in the diet (being meticulous about caloric deficit), and that a calorie deficit can be achieved with any choice of exercise. In a perfect world, I’d have you doing all three elements, with that order of priority: Nutrition, weight training and cardio training and adjust the prescription for the two types of training based on your goals and time available.
The muscle and metabolism argument: Was this point overlooked?
Although this study had limitations and subjects had less than stellar results, it did have its strengths and it did raise some good questions. For example, it has been widely believed for years, especially in the bodybuilding world, that if increasing lean mass increases metabolism, then increasing your lean mass will help you lose weight. It has sometimes even been implied or stated directly that you can sit on the couch or sleep and (with your new muscle), you’ll burn more calories and lose more fat from that alone.
The Duke researchers questioned this. They wrote:
“It may be time to seriously reconsider the conventional wisdom that resistance training alone can induce changes in fat mass due to an increase in metabolism.”
It’s well known that an increase in lean body mass leads to an increase in basal metabolic rate. Therefore, for years, we have promoted the idea that gaining lean mass helps with fat loss – and it does to some degree. However, does it help so much that we can say increasing lean mass, by itself, is a great fat loss strategy? If you only gain a few pounds of lean body mass, the increase in metabolism is nothing to write home about. Without dietary control, it’s no help at all.
It seems to me that the researchers could have made this their primary conclusion. Instead, they said, “Aerobics is better than weight training for fat loss.” That’s where I think they mixed up their message, because weight training does help with fat loss in the short term, directly and significantly, from increased calorie expenditure. Over the long term it helps too, but maybe not as much as we thought purely from increased basal metabolism.
Because the research is so inconclusive and opinions always vary due to personal preferences and ideaologies, the weights versus cardio (and what kind of each) debates are likely to continue. But if you consider the entire body of research we have today on improving body composition, combined with the real world experience of the top trainers and athletes who are in the trenches, you can find it very easy to conclude that the optimal method of fat loss is a combination of cardio training and resistance training.
Is more time required to do both resistance and aerobic training? Yes, but with proper program design, time efficiency can be greatly increased. And isn’t it worth doing both, so you can gain ALL the benefits: burning more calories, increasing your strength, gaining lean muscle, decreasing your body fat, improving your health and transforming your entire body shape?
Aerobics helps increase fat loss and you can lose body weight and body fat with aerobics alone. But pumping iron should stay high on your fat loss strategy list. Which of these two – cardio or weights – gets the most priority and time from you may depend on your personal goals, but almost everyone can agree that either way, controlling your diet is critical.
When you add in motivation and accountability, that increases compliance to those first three elements, and you have as close to a “no fail” program as you’ll ever have…Hey… doesn’t that sound a lot like Burn the Fat, Feed the Muscle?
Effects of aerobics and/or resistance training on body mass and fat mass in overweight or obese adults. LH Willis et al, Journal of Applied Physiology, 1831-1837, December 2012. Duke University Medical Center