August 13th, 2009
“Exercise Won’t Make You Thin” (Why Time Magazine Owes the Fitness Industry a Big Fat Apology)
At first I was tempted to title this article, “why John Cloud and the editors of Time magazine are idiots.” But then I thought that might be a bit harsh and decided to simply call for an apology and a correction for all the errors they made in last week’s article, Why exercise won’t make you thin.
I wasn’t even going to write this at first, because I figured that sending it to my 300,000+ subscribers would only draw more attention to the TIME story, and they’ve gotten enough free publicity from the blogosphere already.
But after receiving countless e-mails from my Burn The Fat subscribers, all imploring me to write a rebuttal, and then after receiving the email from the American College of Sports Medicine (ACSM) yesterday, I reconsidered.
The ACSM said:
“Last Friday, an article appeared in Time Magazine making statements that we believe run counter to fact and the public interest. The article claimed that exercise, contrary to the research with which we are all familiar, is not an effective health tool, particularly as it pertains to weight loss…”
They continued, (addressing the fitness professionals on their mailing list):
“Your assistance is needed in getting the right health message out to the public. Also we encourage you to adapt our letter to the editor and submit it to your local news outlets, helping readers and viewers get the best evidence-based facts and information. “
Assistance has arrived. Here is the right health message that the ACSM was calling for.
I believe you’ll find my information below more accurately reflects the facts than TIME’s one-sided story.
Feel free to forward this information to your friends and colleagues. Link to this, Digg this, re-tweet this and share this on facebook. I also encourage you to send your letters to the editors of TIME.
The truth about exercise, appetite and weight loss
John Cloud, a writer for Time magazine, says that he gets hungry after exercise, so he often eats more on the days he works out than on the days he doesn’t. Therefore, he proposes that exercise won’t make you thin and might actually prevent you from losing weight.
You don’t say? You mean that you don’t lose weight if you put the calories you just burned right back in by stuffing your face with muffins and doughnuts! Who’d have thunk?
It’s tough not to pick on a “fitness journalist” who thinks that exercise turns fat into muscle. But sarcasm aside for a moment, exercise can increase hunger in some cases. Hunger is a normal regulatory response of the body to maintain energy balance and weight homeostasis anytime you’re in a calorie deficit and losing body mass, whether that is achieved through exercise or dietary restriction.
That doesn’t mean exercise is ineffective for weight loss, it means you need DIETARY RESTRAINT to lose weight! Dietary restraint means that if you want to lose weight, sometimes you have to feel hungry and NOT EAT! (even while stressed, emotional, tempted, etc.)
This takes work, and part of that work is to practice the self-discipline to not eat every time you feel the urge and to pursue the self-education to understand the realities of the energy balance equation.
You’ll have to provide the self-discipline, but let me see if I can help with the education part (pay attention, Time magazine!)
Not exercising = not smart
The International Journal of Obesity recently published a review of the effects of exercise on appetite regulation. Dr. Martins of the Obesity research group in Norway explained that in our obesogenic environment today, NOT exercising is likely to lead to weight gain:
“It has been systematically shown that the adoption of a sedentary lifestyle inevitably produces a state of positive energy balance, as the physiological system is unable, at least in the short to medium term, to compensate by decreasing energy intake.”
Translation: if you sit on your butt, and you live in a Western society in this technologically-advanced, convenience-based world, surrounded by eating cues and temptation, it is hard NOT to gain weight, especially for people with a genetic predisposition to obesity.
Exercise does NOT always increase appetite
Dr. Martins’ review, based on 110 related studies, also explained that exercise does not necessarily stimulate energy intake:
“There have been a multitude of studies published in the last two decades exploring the association between exercise and food intake. The majority of them have shown that acute exercise does not increase hunger or energy intake.”
In the Proceedings of the Nutrition Society, Dr. Neil King of The Human Appetite Research Unit at Leeds University Psychology department agreed with Martins’ findings:
“Despite the commonly held belief that the energy demand created by exercise automatically generates a drive to eat, the evidence for this is weak.”
That’s right, some studies do show that exercise increases appetite, but the majority say it doesn’t.
Cloud has committed the journalistic sin known as “cherry picking,” where he selectively reported the few studies that supported his viewpoint, while conveniently “forgetting” to mention the many that didn’t.
Exercise may even DECREASE appetite
To further throw a wrench in Cloud’s argument, some studies even suggest that exercise DECREASES appetite.
Cloud’s article in TIME says, “Be warned: fiery spurts of vigorous exercise could lead to weight gain.”
That’s not what the research says. Studies confirm that high intensity exercise in particular, will reduce hunger.
In The Proceedings of the Nutrition Society, Dr. King wrote:
“In contrast to the idea that a compensatory rise in hunger should follow exercise, many studies have shown that following a bout of intense exercise (> 60% of maximum 02 update), hunger is actually suppressed.”
A study from Laval University in Quebec (Yoshioka) concurred:
“Indeed it would seem that in the post-exercise period, high-intensity exercise seems to inhibit energy intake to a greater extent than a low-intensity exercise session of the same caloric cost.”
You may have heard that high intensity interval training (HIIT) is a very time-efficient form of exercise and that it not only leads to increased levels of fitness, but is also effective for fat loss. Now you can add to the list of benefits for HIIT — it helps support fat loss by suppressing energy intake after the workout.
Does this mean you should abandon low or moderate intensity cardio? Absolutely not. Although low intensity exercise burns fewer calories per unit of time than high intensity cardio, there is plenty of research which proves that steady state exercise such as walking or cycling is also effective for weight control.
A study from the School of Biomedical and Molecular Sciences at the University of Surrey in the UK found that after 60 minutes of cycling, hormones released from the gut were responsible for a suppression of appetite after exercise:
“Acute exercise, of moderate intensity, temporarily decreased hunger sensations and was able to produce a short-term negative energy balance.”
Exercise is the key to long term weight maintenance
When it comes to long term weight maintenance, the importance of exercise is even more critical. Virtually all the weight loss experts and research studies agree: a high level of physical activity is the number one key to maintaining your ideal weight after weight loss.
One of the best examples of this comes from the National Weight Control Registry (NWCR). The NWCR has been tracking the habits of successful maintainers for years. They published a new report in 2008 revealing that people who are successful at maintaining their weight loss are an extremely physically active group.
Exercise may increase appetite over time, but not enough to cancel out the weight loss benefits
Even if exercise did increase appetite 100% of the time, that STILL wouldn’t mean exercise is ineffective. When there is an increase in hunger and energy intake after exercise, the increase is not significant enough to cancel out the benefits.
In a review paper published in the journal Sports Medicine, Alan Titchenal of Department of Nutrition and Food Intake Laboratory at UC Davis wrote:
“When energy intake increases in response to exercise it is usually below total energy expenditure, resulting in negative energy balance and loss of bodyweight and fat. Thus, if energy intake is expressed relative to energy expenditure, appetite is usually reduced by exercise.”
In a study titled, “Cross talk between physical activity and appetite control” JE Blundell confirmed it:
“There exists a belief that physical activity drives up hunger and increases food intake, thereby rendering it futile as a method of weight control. There is however, no evidence for such an immediate or automatic effect…”
“The immediate effect of taking up exercise is weight loss. Subsequently, food intake begins to increase in order to provide compensation for about 30% of the energy expended in activity. The compensation is partial and incomplete.”
Blundell’s comments underscore the fact that you have to go on quite an unrestrained eating binge in order to completely undo the effects of an effective exercise program.
I still can’t help but laugh at Time magazine’s article, which was mostly journalistic sensationalism passed off as science, when you consider how utterly obvious and intuitive all these research findings are. Binge after working out and you don’t lose weight? No kidding?
Listen, it’s not my intention to be purely sarcastic or suggest that some people aren’t experiencing exactly what the article described: some people are doing a lot of exercise and still not losing weight. I don’t dispute that. The problem is in their explanation about why they’re not losing weight.
It’s NOT because exercise doesn’t help with weight loss. It’s because some people over-compensate for the calories burned through exercise by eating more. However, that is an argument for proper nutrition, not an argument against exercise.
Why doesn’t all the research agree?
Why do some studies say that exercise isn’t effective for weight loss? Part of the answer is due to experimental designs. Some studies did not include a control group and many estimated energy intake by self report, which is notoriously inaccurate, as most people underestimate how much they eat (Lichtman 1992).
And why do a few studies say that exercise increases appetite and excess food intake? That too depends on study designs as well as individual differences: Lean or obese? Male or female? Under what conditions? Fed or fasted exercise? Dieted down or just starting the diet? Under stress or without stress? With or without social support? The macronutrient composition of the diet and timing of the meals can also influence the outcome.
When discussing weight loss, exercise and appetite, not just in the mainstream media, but even in the scientific literature as well, it’s also a common mistake to generalize and the type of exercise is often not specified.
High, medium or low intensity? Aerobic exercise or strength training? (the latter can increase lean body mass, offsetting weight loss). And what kind, specifically?
Certain types of exercise, such as swimming in cold water, are well known to increase appetite, while others like HIIT, can suppress appetite.
And why research scientists in this day and age think exercise only means aerobics is beyond my comprehension. What about weight training?
The relationship between exercise and appetite is complex. Every one of these factors can influence whether exercise affects energy intake and subsequently, the amount of weight loss.
Individual variability uncovered: Compensators vs non compensators and restrained vs unrestrained eaters
Studies show that a fixed amount of exercise will not lead to the same amount of weight loss in all individuals. On the surface, this leads one to think that indeed exercise doesn’t work or there are differences in individual response to exercise and biological ability to lose fat (genetics, etc.).
The truth is, most of the variability in results can be accounted for by the type of exercise and study designs as I mentioned above, by behavioral factors and lack of compliance. That’s right, most people just don’t stay on their diets consistently – they may exercise more, but also eat more, and move less the rest of the day, which cancels out the calorie deficit. Researchers call these individuals “compensators.”
There are people who appear to compensate “automatically” for genetic or biological reasons, but there are also non-compensators who adjust their nutrition and training according to their results. You are never influenced only by genes, but also by behavior and environment. How well you comply with your diet and exercise programs and what kind of results you get are ultimately up to you and your level of dietary restraint.
Some people choose to eat inappropriately after exercise because they think they deserve a reward or they over-estimate how many calories they burned during their workout. That has nothing to do with exercise not helping with weight loss. That is called a dietary blunder! It is entirely possible for an un-educated or unrestrained eater to out-eat even the best workout program and highest levels of physical activity.
The bottom line:
The effectiveness of exercise for weight loss was never really in question. The real issue is compliance to a calorie deficit.
Exercise IS effective for weight loss – significantly so – especially when you combine weight training and cardio training with an effective nutrition plan, as I have recommended for years in my Burn the Fat, Feed the Muscle program.
The health benefits of exercise are indisputable. Not to mention that training makes you look good naked. No amount of dieting will ever make you stronger, fitter and more muscular. Only training can do that. Dieting without exercising turns you into a skinny fat person. You may look thin in clothes, but when you take off the shirt, you will still look soft and flabby.
But no matter how much you exercise, you can’t lose weight if you eat yourself into a calorie surplus. Just because you start an exercise program doesn’t mean you have free license to abandon all restraint and freely indulge in eating anything you want.
So whaddya say, TIME magazine? Do you acknowledge your errors? Will you write a retraction? Thousands of fitness professionals and hundreds of thousands of fitness enthusiasts are eagerly awaiting your answer.
- Tom Venuto, author of:
Burn The Fat Feed The Muscle
Founder & CEO,
Burn The Fat Inner Circle
Blundell JE, cross talk between physical activity and appetite control: does physical activity stimulate appetite? Proc Nutr Soc, 62, 651-661. 2003
Catenacci VA, Phelan S, Wing RR, Hill JO. Physical activity patterns in the national weight control registry. Obesity research. 16: 153-161, 2008
Donahoo WT, Variability in energy expenditure and its components. Curr Op Clin Nutr Metab. 7: 599-605. 2004.
Hubert P, et al, Uncoupling the effects of energy expenditure and energy intake: appetite response to short-term energy deficit induced by meal omission and physical activity. Appetite. 1998 Aug;31(1):9-19.
King NA, et al, Individual variability following 12 weeks of supervised exercise: Identification and characterization of compensation for exercise-induced weight loss. Int J Obes, 32, 177-184, 2008.
King NA, effects of exercise on appetite control: Implications for energy balance. Med Sci Sport Exer, 29(8): 1076-1089. 1997
King, NA, The relationship between physical activity and food intake. 57: 77-84. 1998.
Lichtman, S., Discrepancy between self-reported and actual caloric intake and exercise in obese subjects. NEJM. 327: 1893-1898. 1992
Lluch A, Exercise enhances palatability of food, but does not increase food consumption, in lean restrained females. Int J Obes, 21: supp a129.
Melzer K., effects of physical activity on food intake. Clin Nutr, 24: 885-895. 2005
Slentz CA. Effects of the amount of exercise on body weight, body composition, and measures of central obesity. Arch Intern Med. 164: 31-39. 2004
Titchenal A., Exercise and Food Intake: what is the relationship? Sports Med, 6: 135-145. 1988
White, L., Increased caloric intake soon after exercise in cold water. Int J Sport Nutr Exer Metab, 15: 38-47, 2005. University of Gainesville, FL USA.
Yoshioka M, Impact of high-intensity exercise on energy expenditure, lipid oxidation and body fatness. Int J Obes. 25, 332-339. 2001.