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Top 7 Official Obesity Myths (But Are They Really?)

Published on February 5, 2013,

The New England Journal of Medicine has published a paper by a number of leading obesity researchers titled, “Myths, Presumptions, and Facts About Obesity“. It details what the authors describe as seven popular obesity related “myths“, six common “presumptions“, and nine understated evidence supported “facts“. However, Dr Yoni Freedhoff, on his blog Weighty Matters, gives his take on the myths and doesn’t agree in all cases…

What scientists call

(Photo credit: Wikipedia)

These are subjects that the authors feel have sufficient data to conclusively dismiss them as false. While I agree in some cases, I don’t in all. That doesn’t necessarily mean the authors are wrong and that I’m right, just that our opinions differ:

 1. “Small sustained changes in energy intake or expenditure will produce large, long-term weight changes”.

(Agree this is a myth. Putting this another way, I’ll often tell my patients weight loss is insert-adjective here. Meaning small changes only lead to small losses and if you want to lose a huge amount of weight, you’ll need to undertake (and sustain) a huge amount of change.)

 2. “Setting realistic goals for weight loss is important, because otherwise patients will become frustrated and quit”.

(Disagree. Not that the statement’s true or false, just that the authors call it a myth consequent to the fact that there isn’t robust evidence proving it to be true or false. Until there’s robust evidence one way or the other, tough to call this one a myth and I’d have put it into their “presumptions” section. Moreover, tough to apply to everyone as no doubt some people likely respond wonderfully to aggressive goals, while others quit consequent to not reaching a dream destination.)

 3. “Large, rapid weight loss is associated with poorer long-term weight-loss outcomes as compared with slow, gradual loss”.

(Disagree. Here again is an area where I don’t think we have sufficient data. The authors refer to year-long studies as long term data and frankly I don’t think that’s long term. For instance if a person rapidly loses 80lbs during an 8 month meal-replaced, very-low-calorie-diet looking at 1 year as “long term” only gives that person 4 months to regain. So I’d argue anything less than 2 year data is a short-term outcome and that we need data from at least 2 or more years out to draw long term conclusions and that’s truly rare to come by.)

 4. “It is important to assess the stage of change or diet readiness in order to help patients who request weight-loss treatment”

(Disagree. Here the authors report that studies that have looked at stage of change in people voluntarily entering weight loss programs didn’t predict outcomes. Yet as the authors themselves point out, by definition folks voluntarily choosing to enter weight loss programs are at least minimally ready to face change. But for the clinician working their primary practice and not a practice like mine for instance, no doubt stage of change assessment crucial – if not for success than certainly for a respectful doctor patient relationship.)

 5. “Physical-education classes in their current form, play an important role in reducing or preventing childhood obesity”

(Here all I can say is AMEN. No doubt evidence very clearly suggests kids aren’t going to burn off or prevent obesity by means of school based PE classes.)

 6. “Breast-feeding is protective against obesity”

(The authors report that a WHO meta-analysis on the subject was flawed, and that well controlled trials failed to demonstrate any clear benefit to breastfeeding on reducing obesity risk.)

 7. “A bout of sexual activity burns 100 to 300 kcal for each participant”

(By their calculations the authors predict the average act of intercourse burns in the neighbourhood of 14 calories (sorry folks).)

More (including the lists of ‘presumptions’ and ‘facts’) at Weighty Matters:  The New England Journal’s Obesity Mythbusting


Low carb and Mediterranean diets beat low fat for weight loss and health markers over 6 year study

Published on October 8, 2012,

A letter has been published in the New England Journal of Medicine giving a follow up to a study comparing low carb, low fat and Mediterranean diets, first published after two years, now after an additional four years.


The results suggest participants on a low carb diet, who had lost most weight after two years, had put a proportion of this back on after six years but still showed significant weight loss overall – but not as much as those on the Mediterranean diet. The low carb and Mediterranean dieters also showed significant improvement in key health markers such as triglycerides, cholesterol and the ratio of HDL to LDL cholesterol. Participants on the low fat diet showed the least benefit in terms of both weight loss and health markers. This is from the New England Journal of Medicine…

Changes from Baseline in Diet-Related Measures
(courtesy of New England Journal of Medicine)

For the entire 6-year period, the total weight loss was 0.6 kg in the low-fat group, 3.1 kg in the Mediterranean group, and 1.7 kg in the low-carbohydrate group (P=0.01 for all comparisons) (Figure 1A FIGURE 1Changes from Baseline in Diet-Related Measures.). There was a significant difference in total weight loss between the low-fat group and the Mediterranean group (P=0.01) but not between the low-fat group and the low-carbohydrate group (P=0.44) or between the Mediterranean group and the low-carbohydrate group (P=0.22). Overall, as compared with the weight at baseline, the 6-year weight loss was significant for the Mediterranean group (P<0.001) and the low-carbohydrate group (P=0.02) but not for the low-fat group (P=0.28).

At 6 years, changes from baseline in the ratio of low-density lipoprotein cholesterol to high-density lipoprotein cholesterol were similar in the three groups (P=0.62 for all comparisons), although the change in the ratio was significant in the low-carbohydrate group (a reduction of 0.16, P=0.04) (Figure 1B). Reductions in triglyceride levels from baseline were significant in the Mediterranean group (21.4 mg per deciliter [0.24 mmol per liter], P=0.03) and the low-carbohydrate group (11.3 mg per deciliter (0.13 mmol per liter], P=0.02), with no significant difference among the three groups (P=0.12) (Figure 1C). Overall, there were persistent and significant reductions from baseline in total cholesterol levels in all three study groups, with reductions of 7.4 mg per deciliter (0.19 mmol per liter) in the low-fat group (P=0.03), 13.9 mg per deciliter (0.36 mmol per liter) in the Mediterranean group (P=0.001), and 10.4 mg per deciliter (0.27 mmol per liter) in the low-carbohydrate group (P=0.02; P=0.71 for all comparisons) (Figure 1D).

In conclusion, a 2-year workplace intervention trial involving healthy dietary changes had long-lasting, favorable postintervention effects, particularly among participants receiving the Mediterranean and low-carbohydrate diets, despite a partial regain of weight.

More at: Four-Year Follow-up after Two-Year Dietary Interventions

Research suggests sugary drinks are the biggest cause of America’s obesity epidemic

Published on September 24, 2012,

As Americans debate what is most to blame for the nation’s obesity epidemic, researchers say they have the strongest evidence yet that sugary drinks play a leading role and that eliminating them would, more than any other single step, make a huge difference. This is from the Daily Mail…

New York City Mayor Michael Bloomberg opening ...

New York City Mayor Michael Bloomberg who wants to limit portion sizes of sugary drinks. (Photo credit: Wikipedia)

A huge, decades-long study involving more than 33,000 Americans has yielded the first clear proof that drinking sugary beverages interacts with genes that affect weight, amplifying a person’s risk of obesity beyond what it would be from heredity means alone.

This means that such drinks are especially harmful to people with genes that predispose them to weight gain. And most of us have at least some of these genes.

In addition, two other major experiments have found that giving children and teens calorie-free alternatives to the sugary drinks they usually consume leads to less weight gain.

‘I know of no other category of food whose elimination can produce weight loss in such a short period of time,’ said Dr. David Ludwig, director of the New Balance Foundation Obesity Prevention Center at Boston Children’s Hospital, who led one of the studies.

‘The most effective single target for an intervention aimed at reducing obesity is sugary beverages.’

Collectively, the results strongly suggest that sugary drinks cause people to pack on the pounds, independent of other unhealthy behavior such as overeating and getting too little exercise, scientists say.

That adds weight to the push for taxes, portion limits like the one just adopted in New York City by Major Michael Bloomberg, and other policies to curb consumption of soda, juice drinks and sports beverages sweetened with sugar.

Soda lovers do get some good news: Sugar-free drinks did not raise the risk of obesity in these studies.

The studies were presented Friday at an obesity conference in San Antonio and published online by the New England Journal of Medicine.

More at: Perhaps Bloomberg’s right after all: Sugary drinks ARE the biggest cause of America’s obesity epidemic

Here a link to the original research in the New England Journal of Medicine.

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