7 weight loss myths (sort of) debunked
January 31st, 2013
11:10 AM ET

7 weight loss myths (sort of) debunked

There's a lot said about how to lose weight. As it turns out, a lot of what's said may not be true.

To sort fact from fiction, a group of doctors and nutritionists researched the medical evidence behind common claims and presented their findings Wednesday in the New England Journal of Medicine.

Beyond academia, however, the doctors and nutritionists also have deep ties to industry, receiving grant support and consulting fees from food, drug, and diet companies, raising questions about how wide a net of inquiry the authors were willing to cast.

Still, here are what the researchers say are the seven myths about obesity:

1. Weight loss is just "calories in" vs. "calories out"

"Predictions suggesting that large changes in weight will accumulate indefinitely in response to small sustained lifestyle modifications rely on the half-century-old 3,500 calorie rule, which equates a weight alteration of 2.2 lb to a 3,500 calories cumulative deficit or increment," write the study authors.

The 3,500-calorie rule "predicts that a person who increases daily energy expenditure by 100 calories by walking 1 mile per day" will lose 50 pounds over five years, the authors say. But the true weight loss is only about 10 pounds if calorie intake doesn't increase, "because changes in mass ... alter the energy requirements of the body."

"This is a myth, strictly speaking, but the smaller amount of weight loss achieved with small changes is clinically significant and should not be discounted," says Dr. Melina Jampolis, CNN diet and fitness expert.

2. Set realistic weight-loss goals  

The thinking here is that people who aim too high might be setting themselves up for disappointment.

"Although this is a reasonable hypothesis, empirical data indicate no consistent negative association between ambitious goals and program completion or weight loss," write the study authors.

"Indeed, several studies have shown that more ambitious goals are sometimes associated with better weight-loss outcomes."

 3. Big, fast weight loss won't stick 

Going on a very restrictive diet led to faster weight loss, the study authors found, and dieters did not necessarily gain that weight back, either.

"There was no significant difference between the very-low-energy diets and low-energy diets with respect to weight loss at the end of long-term follow-up," write the authors.

4. You won't lose the weight unless you're really ready 

"Readiness does not predict the magnitude of weight loss or treatment adherence among persons who sign up for behavioral programs or who undergo obesity surgery," write the study authors.

Why not?

"The explanation may be simple - people voluntarily choosing to enter weight-loss programs are, by definition, at least minimally ready to engage in the behaviors required to lose weight."

5. Kids are losing weight in physical education class 

"Physical education, as typically provided, has not been shown to reduce or prevent obesity," write the study authors.

"That doesn't take away the fact that physical activity has been consistently associated with decreasing childhood obesity," says Krista Casazza, the lead study author.

"But the way physical education is currently given in the schools is the issue. Oftentimes, it's just kids going outside or being in a physical education class. It has to be an actual, purposeful event."

6. Breast-feeding reduces child obesity

"Although existing data indicate that breast-feeding does not have important anti-obesity effects in children, it has other important potential benefits for the infant and mother and should therefore be encouraged," write the study authors.

7. Sex is a good workout

Well, depending on how you do it.

The researchers cite evidence that sex takes about as much exertion per minute as going for a walk, but lasts on average about six minutes. That adds up to about 21 calories, which isn't such a good workout, but may be good for stress relief.

"Does it make any difference if you do calorie labeling? Does it make any difference if you cap soda size? Does it make any difference if you remove food advertising to children from television?" says Marion Nestle, professor of nutrition at New York University who is not associated with the study.

"Those are the really important things that people are looking at to change the environment of food choice to help people eat more healthfully, and I don't see any of that in here."

Filed under: Diet and Fitness • Myths • Obesity • Weight loss

soundoff (158 Responses)
  1. Kandi

    Did this article (sort of) say anything useful?

    January 31, 2013 at 12:23 | Report abuse | Reply
    • Alex


      I just read it again.

      Still no.

      January 31, 2013 at 22:34 | Report abuse |
    • Robert

      Well, it doesn't entirely, but it still might. Sort of. At least according to one study.

      January 31, 2013 at 22:55 | Report abuse |
    • Chef Sun

      Of course it's useful. It confirms what most of us have suspected all along and we can use this to support our position when know it alls try to promote their weight loss myths. My boy goes to mandatory phys ed. classes everyday which is a total waste of time and tax payer's money because they don't really do anything useful or fun while there. Sitting around in that class probably gains a few ounces each day.

      February 1, 2013 at 02:10 | Report abuse |
    • magurkin52

      Nah... Waste of 2 minutes of my life.

      February 1, 2013 at 02:23 | Report abuse |
    • Dr. Marc

      To be clear: Calories in = Calories out. It has to by mere defintion of a calorie. Sorry but my Ph.D in organic and biochemistry trumps your internet reserach.

      Marc W. Andersen

      February 5, 2013 at 08:36 | Report abuse |
    • Taysha

      Dr Marc:

      Good Calories, Bad Calories, by Gary Taubes. Among many others.

      Calories in =/= calories out.


      I train PhDs at the bench.

      February 5, 2013 at 10:17 | Report abuse |
    • quitsmokingplease

      With all due respect, I the calories in calories out theory is the myth. Saying that mathematically, you simply need to reduce 3500 calories then you took in either by exercise or diet restriction to lose a pound of fat is over simplifying. The truth is, our bodies react differently, depending on the types of food that is taken in. With this in mind, other issues such as stress can trump weight loss. Perhaps I should have written the article. 🙂 if someone wants to lose weight, they need to watch their insulin levels, reduce their stress, and become more active in life. You do those three, you will see results not only physically, but mentally...and it will be a quicker transition.

      February 5, 2013 at 20:20 | Report abuse |
  2. Sy2502

    Weight loss is just "calories in" vs. "calories out"

    In other news, the laws of thermodynamics are wrong.

    Seriously folks? Are we still trying to wiggle our way out of the well known and absolutely obvious fact that, to lose weight, you need to eat less? Just so you know, those of us who DO follow the "calories in vs calories out" method are losing weight, and keeping it off, just fine.

    January 31, 2013 at 13:58 | Report abuse | Reply
    • Daniel

      You are right, but people are calculating calories out incorrectly. They incorrectly assume that you will burn the same amount of calories today as you will 5 years from now with the exact same habits. While walking 1 mile burns pretty much the same amount of calories in the two situations, what people aren't realizing is that the vast majority of calories out does not come from physical activity, but rather comes from your baseline metabolism. That can, and definitely does change as a function of time, and usually goes down every year. Thus, people who stick to the exact same habits WILL see diminishing returns on their weight loss, because they aren't really measuring calories out correctly.

      January 31, 2013 at 14:35 | Report abuse |
    • Maya

      I don't think that is what the article is saying. The article is saying, correctly, that it is wrong to assume that you will lose weight in a linear fashion getting the same amount of exercise or cutting the same amount of calories. We've known that for a long time, but people fail to account for it. Say your current calorie needs, just to maintain weight, is 1800 calories a day. If you eat just 1400 calories a day, you will indeed lose weight. However, the rate at which you lose weight will steadily decrease the more weight you lose because your calorie needs will decrease right along with your weight. Eventually, you will just stop losing weight. At that point, you need to cut more calories if you want to keep losing weight (although if you only need 1400 calories a day to maintain weight, you probably don't need to lose weight). Similarly, the amount of calories burned during exercise depends in large part on your current weight. The more you weigh, the more calories burned for the same amount of exercise. As you lose weight, you either need to exercise more vigorously or for longer periods in order to burn the same amount of calories.

      January 31, 2013 at 21:52 | Report abuse |
    • Alex

      It's basically saying that if you don't recalibrate based on your new body mass, weight loss will stall. So it's wrong- weight loss DOES mean calories in versus calories out, it's just that "calories out", including basal metabolic rate, changes as body mass changes. Which... I mean.... duh?

      Silly article. Nothing to see here, folks. No need to change what you're doing.

      January 31, 2013 at 22:36 | Report abuse |
    • Dr. Marc

      To be clear: Calories in = Calories out. It has to by mere defintion of a calorie. Sorry but my Ph.D in organic and biochemistry trumps your internet reserach.

      Marc W. Andersen

      February 5, 2013 at 08:35 | Report abuse |
  3. Jenna

    Honestly, losing weight has a lot to do with what you're eating and more important NOT eating. You should check out this article that contains 5 foods you should completely avoid to lose weight. Helped me a lot and they mention that you don't even need diet pills to lose the weight. http://foodstonevereat.blogspot.com

    January 31, 2013 at 21:43 | Report abuse | Reply
    • pazke

      Who ever said you needed diet pills to lose weight?

      January 31, 2013 at 22:28 | Report abuse |
  4. lwik

    poorly written, poorly researched. Does not consider the breadth of research in this area. These 'myths' are not simple enough to adequately discuss in this type of brief snapshot article.

    January 31, 2013 at 22:01 | Report abuse | Reply
  5. yanks9596

    Your sex life must be very satisfying.

    January 31, 2013 at 22:04 | Report abuse | Reply
  6. Fiona

    Eat less. Move more. Basic truths.

    February 1, 2013 at 00:26 | Report abuse | Reply
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    February 1, 2013 at 00:53 | Report abuse | Reply
  8. Alex

    You made some excellent points in that post. I find this a really interesting subject.
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    February 1, 2013 at 04:11 | Report abuse | Reply
  9. Take To Task

    I disagree with "calories in vs calories out" being just a myth. Perhaps the way they presented it here is, but "calories in vs calories out" appropriately describes the best way to lose weight.

    "Calories in vs calories out" is exactly what my doctor told me in March 2011, when I weighed 203 lbs. In less than 5 months, I was down about 40 lbs.

    I did nothing drastic. I just cut my portions down. I didn't measure food or stop eating ice cream. I just got smart with the amount of food. After the first 7 pounds came off, I added small exercise routines.

    Cost of food == no change
    Cost of gym == n/a
    Cost of gym-like equipment == n/a
    Cost of exercising on the floor while watching TV == FREE

    The revolution starts now. Lose the weight without paying anyone else another ¢.

    Except Carl!™

    February 1, 2013 at 11:09 | Report abuse | Reply
  10. kristin

    http://www.fit4america.com has helped me overcome.

    February 1, 2013 at 15:04 | Report abuse | Reply
  11. Liam Rubel

    If you go through many websites it contains weight loss tips including all the information which is cited for myths related to weight loss. But some times the tips work outs.

    February 2, 2013 at 04:57 | Report abuse | Reply
  12. Jenna

    Sad to see that still many people think that these myths a true. Thanks for some enlightment (I belonged to these people).
    I just started my own blog about weight loss some feedback would be much appreciated!


    February 2, 2013 at 13:14 | Report abuse | Reply
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    February 2, 2013 at 14:59 | Report abuse | Reply
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    Decent post although it reiterates pretty much everything we already know. I learn more over at http://lose-weight-naturally-blog.com/ if u guys wanna check it out

    February 2, 2013 at 19:59 | Report abuse | Reply
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    7 Weight Loss Strategies

    February 3, 2013 at 07:51 | Report abuse | Reply
  16. Pinakin Bhadeshiya

    It was a wonderful post to read I really appreciate your efforts 🙂

    February 4, 2013 at 01:20 | Report abuse | Reply
  17. scribb

    I wish I was employed in the nutrition/weight loss industry because clearly all you have to do is rearrange facts every few years.

    February 5, 2013 at 02:18 | Report abuse | Reply
  18. Dr. Marc

    To be clear: Calories in = Calories out. It has to by mere defintion of a calorie. Sorry but my Ph.D in organic and biochemistry trumps your internet reserach.

    Marc W. Andersen

    February 5, 2013 at 08:39 | Report abuse | Reply
  19. Another PhD

    I'm a PhD scientist also. "Calories in = calories out" does not take into account how those calories are metabolized, and who is doing the metabolizing (I presume Dr. Marc does not poop, or have any gut flora who happily are doing much of the work of converting hard-to-assimilate complex food calories into calories that end up being metabolized by humans?). We aren't calorimeters. Just because there is energy content in food it isn't necessarily going to be readily available. This is what can change over time as well as how the body uses those calories it does get. It is also why carbohydrate-rich foods tend to cause weight gain – they are very easily converted into simple sugars using only digestive enzymes, so we can utilize them quite efficiently without the help of gut bacteria. If all one ate were glucose, then "calories in = calories out" might be very valid, and predictive of weight gain or loss. As soon as we eat more complex calorie sources then things start to get much less clear. For example, consuming fats can use a lot of calories due to beta oxidation – at the end of the process there is available energy, but getting it takes some metabolic work. If it is your gut bacteria doing that then you can produce lot of kilos of bugs and might not be getting all that much absorbable calories. one reason why Atkins diet actually works for many people, contrary as it might seem.

    February 5, 2013 at 12:08 | Report abuse | Reply
  20. dailygrindonline

    Losing weight and keeping it off is a complex thing and varies from one person to the other. It does seem that if you burn more calories than you take in that you're going to lose weight. In most cases, I would think that the causes of weight gain or obesity are pretty obvious, like sitting in front of the TV for hours on end and snacking. In my opinion, 50% of the battle against obesity is portion control, avoiding a sedentary lifestyle (getting some physical activity every day), and being aware of what you're eating and what you should be avoiding or limiting. Unfortunately for us dessert and snack lovers, the list is long!

    February 6, 2013 at 10:07 | Report abuse | Reply
  21. mizzpicklezz

    CNN is shady!! They had another doctor write an article about this same study yesterday that was more supportive of the findings. I read the study and found it very interesting that Coca-Cola and Kraft funded most of the study, and the study concluded that snacking didn't effect weight loss... and that none of the doctors and the lone RD on the study mentioned nothing about how gaining muscle mass speeds up weight loss. And the Sex myth..yeah I don't know how well they "researched" that one, depending on who you are with it could be a great cardio workout...different positions, different rooms, surfaces..environments etc.. I mean seriously how do you get empirical evidence for that? With Cylindra and Viagra being possible variables that can prolong intercourse and intensity ..is everyone really only burning 21 calories. I'd like to see that particular myth explored more.

    February 6, 2013 at 17:34 | Report abuse | Reply
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    Typical weight loss story with the typical arguments that follow. Over the last 30 years I have training 1000's of people in weight management and fitness. There are certain things that ALWAYS WORK and always will. Check out my best selling fitness book for more info: http://www.corpsstrength.com.

    February 15, 2013 at 19:55 | Report abuse | Reply
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  27. stevejones

    The major problem which the current generation facing is obesity. In this busy life no one has enough time to do physical activities as a result they are facing weight issues and uncontrolled diet is also one of the problems to gain weight. There are so many weight loss myths about diet. Reduction of fat, carbohydrates helps to lose weight but fat is very important for body functionality and carbohydrates are main source of energy in human body. If you want to lose weight you will have a diet plan, make sure that don’t avoid carbs.

    April 29, 2013 at 00:56 | Report abuse | Reply
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    Has anyone honestly just tried the logical thing to do? Eat healthy, stay active, and avoid things you know are bad for you? You would think common sense would kick in.

    May 6, 2013 at 16:24 | Report abuse | Reply
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  31. Ros Bailey

    I am surprised to find that the myth of 'sex is a good workout' persists. How could such a short period of moderate exercise keep one fit? Anyway, I have found eating moderate amounts of food along with exercise effective in losing weight and maintaining a healthy weight. Now that I am in my 50's and my metabolism is slowing, I have found Green Coffee Bean Extract effective in helping me lose weight

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    October 21, 2013 at 17:22 | Report abuse | Reply
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    Losing weight shouldn't be as hard as many people try to make it. People who are desperate to achieve weight loss are often prone to take more risks. The only reason most people fail in their fitness goals is that they have good intentions at first to adopt a new lifestyle, yet after a few weeks or months, they abandon their good intentions and slip right back into their old bad habits that gave them the excess body fat in the first place.


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    Yes, I found this article useful. It is always useful to find out what is and is not myth. Ultimately, we all need to find a system that works, and ultimately we have reduce the amount of calories consumed or burn more calories to prevent weight gain, and/ or enable weight loss. Intensive exercise is a great way to boost metabolism, but if you cannot find the time to do this each day, I would recommend a supplement that helps you absorb less fat. For example, Green coffee bean extract. http://coffeebeaneffects.com

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