Obesity Myths

BATON ROUGE, LA – Popular media and scientific journals contain numerous false and scientifically unsupported beliefs about obesity, according to a new study published in the latest edition of the New England Journal of Medicine. Widespread belief in them, the authors say, is leading to poor policy decisions, inaccurate public health recommendations, and wasted resources.

Louisiana’s Pennington Biomedical Research Center Executive Director Steven Heymsfield, M.D. was part of an international team of researchers that analyzed articles published in the scientific and popular press coverage to separate myths from evidence-supported facts. The authors defined myths as beliefs about obesity, many of which are fervently held, despite evidence to the contrary.

According to Dr. Heymsfield, the article identifies seven obesity related-myths, six presumptions, or widely accepted beliefs, and nine evidence-supported facts that are relevant for the formation of sound public health, policy, or clinical recommendations.  “Obesity is a serious national problem that requires evidence-based findings upon which to base public policy and patient recommendations.  This study sets the baseline for what is founded on fact and myth,” said Dr. Heymsfield.

Myths Identified

The researchers define “myths” as common beliefs without the support of proven scientific evidence through randomized studies to confirm their validity. Myth #1: Small sustained changes in energy intake or expenditure will produce large long-term weight changes. This belief is suggesting that large changes in weight will accumulate indefinitely as a result of small continued lifestyle changes over long periods of time. An example is if an individual increases calorie expenditure by 100 calories by walking a mile a day that over five years that person can lose more than fifty pounds, when the true weight loss is only about ten pounds.

Myth #2:  Setting realistic goals for weight loss is important, because otherwise patients will become frustrated and lose less weight. It appears there is no data which supports that more ambitious weight loss goals negatively impact weight loss. In fact, several studies indicate that grander goals are associated with better weight loss outcomes.

Myth #3: Large, rapid weight loss is associated with poorer long-term weight loss outcomes, as compared with slow, gradual weight loss. Although there may be greater weight loss in the short term (less than a year), there is no difference in pounds lost between very-low-energy diets and low-energy diets (800 to 1200 calories per day) over more than one year.

Myth # 4: It is important to assess the stage of change or diet readiness in order to help patients who request weight loss treatment. As it turns out, readiness does not predict the magnitude of weight loss or treatment adherence among patients who sign up for behavioral programs or undergo obesity surgery. The explanation may be as simple as that people who decide they want to lose weight are at least minimally ready to hold fast to behaviors that are required to lose weight.

Myth #5: Physical-education classes, in their current form, play an important role in reducing or preventing childhood obesity. Physical education, as typically provided, as well as those with specialized school-based programs that promote physical activity did not show a reduction on body mass index (BMI) across sexes and age groups. However, there is almost certainly a level of physical activity (a specific combination of frequency, intensity and duration) that would be effective in reducing or preventing obesity.

Myth #6: Breastfeeding is protective against obesity. After following 13,000 children for more than 6 years, there was no compelling evidence of an effect of breastfeeding on obesity. However, breastfeeding has other important potential benefits for the mother and child and should be encouraged.

Myth #7: One episode of sex burns 100 to 300 calories for each participant. The number of calories burned during sexual intercourse is similar to calories burned while walking at a moderate pace, about 2.5 miles per hour. Given that the average sexual activity lasts about 6 minutes, a man in his early to mid-30s might experience a net effect of burning 14 calories during intercourse with respect to energy expended.

Researchers analyzed popular media and scientific journals to define the myths and presumptions, including social media, websites, mainstream television news and nutrition textbooks via the internet to write the study.  Pennington Biomedical, located in Baton Rouge, is one of the largest nutrition-based research centers in the United States and has, among its faculty, some of the leading obesity research scientists in the world.

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