An editorial was recently published in the British Journal of Sports Medicine, claiming that "you cannot outrun a bad diet". This editorial (not a research study) has spawned a media frenzy of posts that presumably confirm that exercise is worthless in weight loss.
... and my favorite 'all-or-nothing' title:
These titles are wrong. If you go back and read the original editorial, or actually read the current research on the matter (see below), you will see why they are wrong. But, most people do not read the original research. We then depend on the media to read the research for us and state the facts, without twisting an article title into a 'click bait' banner. The danger is that people will now conclude exercise is worthless, when it is not.
First, if you go and read the editorial, they make the statement, "...many still wrongly believe that obesity is entirely due to lack of exercise." Even though I have not personally met anyone who thinks the obesity epidemic is 100% due to lack of exercise, I do agree that this presumption is incorrect.
There are many factors that contribute to the etiology of obesity, even beyond the basic 'calorie-in versus calorie-out' theory – such as, genetics, physiological, environmental, psychological, social, and economic factors.3 The commentary is actually more directed at the harms of the junk food industry on our diet, and the public relations machine that drives it.
Never does this editorial say that exercise or going to the gym is worthless in helping us lose weight. As Dr. David Katz was quoted, "The principal take-away messages of this commentary are that (a) it is hard, if not impossible, to outrun the supply of calories accessible to most of us; and that (b) food choices and diet quality matter regardless of weight, BMI [body mass index], or caloric intake. To both of these propositions, I am inclined to say only: Amen!"
I second the "Amen!" So, the bone to pick here is not with the editorial, which I quite enjoyed, but with the media who have contorted the authors' message into their own bastardized myth.
What Does the Research Actually Say
I think the best, recent summary of the research on physical activity and weight control, is a review article by a group of expert leaders in our field.2
After reviewing all of the research, they conclude that aerobic exercise and physical activity can help you lose weight - even without caloric restriction. For example, the authors explore the following results:
- Daily exercise sessions expending 700 Calories produced an 8% weight loss in obese men after 12 weeks. For reference, 5% weight loss is the gold standard for clinically significant weight loss in individuals classified as obese (BMI ≥ 30).
- 14 weeks of aerobic exercise with an energy expenditure of 500 Calories per session helped overweight-obese postmenopausal women achieve 6.8% weight loss.
- Aerobic exercise training of approximately 2,000 Calories per week helped a group of men lose 5.3% of their body weight after 16 weeks.
The authors conclude, "Thus, clinically significant weight loss is possible with aerobic exercise training without caloric restriction, but it requires a high exercise training volume."
The Real Problem
I believe the real problem or issue here is summed up nicely by the final statement in the above quote,
"Thus, clinically significant weight loss is possible with aerobic exercise training without caloric restriction, but it requires a high exercise training volume.
For the general population, these exercise training volumes may not be practical or sustainable."
The question, then, is not, "will exercise help us lose weight without caloric restriction?" It can.
For most, the question is, "are you willing to do it?" Or, "do you perceive the volume of exercise as impractical or unsustainable?"
Jim and Water Aerobics
For example, Jim is 200 lbs, and is attending a local water aerobics class to help him lose weight. He refuses to change his diet. His aerobics class is a 6 MET, moderate-intensity activity (explore here for more on MET values of various activities). Anything from 3 to 6 METs is considered a moderate-intensity activity, and is a very feasible intensity for most people trying to lose weight. One, 60-minute class would allow Jim to expend almost 550 Calories, in one class.
As you can see, it is feasible for Jim to achieve the needed exercise training volume, but does he want to? Does he interpret the exercise volume as impractical or unsustainable?
"You Cannot Out Eat an Inactive Lifestyle"
I digress, because it would be so much more sensible to use the complimentary combination of physical activity/exercise and healthy food choices. Maybe, then, we could prevent the next article telling us, "you cannot out eat an inactive lifestyle."
As good as healthy eating is, it cannot improve our cardiovascular fitness, which is its own unique predictor of disease, disability, and premature death. Exercise and physical activity can. In addition, we have not even included the positive impact of both aerobic and resistance exercise on body composition (fat and muscle) – beyond just 'weight' loss.1
However, is this knowledge justification to conclude that a whole food, healthy diet of mostly plants is "worthless"?
Caloric Balance: Cutting versus Expending?
Many use the 'calories-in versus calories-out' equation, but exercise is commonly left out. Take the following example:
Carolyn wants to lose weight, but currently eats 3,000 Calories per day from poor food choices. The common prescription asks Carolyn to cut 250 to 500 Calories from her daily intake, in hopes of losing 0.5 to 1.0 pounds of weight per week.
So, she eats the same unhealthy diet, but just cuts out a bit here or there. Since, 1 Twinkie cake is equal to about 21.5 cups of baby spinach (about 150 Calories), we wish Carolyn would choose the healthier option of reducing Caloric intake by improving food quality, but she sticks to the common, Calorie-cutting option.
Carolyn created a 'deficit' of 250-500 Calories per day. There is nothing that mandates this deficit has to come from cutting calories from the diet. Carolyn could also choose to exercise more each day to expend an extra 250-500 Calories. She could even reduce her intake by 250 Calories/day and expend an extra 250 Calories/day, creating the same 500 Calories/day deficit.
Despite what the popular media might want us to believe, exercise/physical activity does help with weight loss and maintenance – while providing additional health, functional, and disease prevention benefits. However, many people, who are physically capable of doing the required exercise/physical activity volume to achieve weight loss without caloric restriction, perceive it as impractical and unsustainable, and are subsequently unwilling to do it.
Ideally, we would sensibly combine our active lifestyles with a healthy, whole food diet of mostly plants, reduced stressed, and enhanced sleep in order to achieve our weight control and health goals.
There is no reason for us to try to "outrun a bad diet", or for that matter, try to "out eat an inactive lifestyle".
- Rossi, F. E., Buonani, C., Viezel, J., Silva, E. P. D., Diniz, T. A., Santos, V. R. D., ... & Ismael, F. (2015). Effect of combined aerobic and resistance training in body composition of obese postmenopausal women. Motriz: Revista de Educação Física, 21(1), 61-67.
- Swift, D. L., Johannsen, N. M., Lavie, C. J., Earnest, C. P., & Church, T. S. (2014). The role of exercise and physical activity in weight loss and maintenance. Progress in Cardiovascular Diseases, 56(4), 441-447.
- Wright, S. M., & Aronne, L. J. (2012). Causes of obesity. Abdominal Imaging, 37(5), 730-732.