7 Obesity Myths Busted: Having Sex Doesn't Burn 300 Calories

Sex helps burn 300 calories. Breast-feeding helps new moms to lose weight. These are just of the diet myths that have now been busted by a new study done.

A report published in Thursday's edition of the New England Journal of Medicine list seven popular "myths" which are fervently held despite evidence to the contrary. 

"False and scientifically unsupported beliefs about obesity are pervasive," study author Dr. David Allison, associate dean for science in the School of Public Health at the University of Alabama at Birmingham, said in a written statement.

"As health professionals, we should hold ourselves to high standards so that public health statements are based on rigorous science."

For the study, Allison and his team conducted Internet searches of popular media and scholarly scientific papers, to come up with a list of obesity-related myths that could have widespread public health implications if believed. The researchers identified seven myths they said were not scientifically-backed by evidence.

Here are the seven myths, explained with implications for public health, policy and clinical recommendations in the NEJM article:

• Myth 1:Small, sustained changes in how many calories we take in or burn will accumulate to produce large weight changes over the long term.

Fact: Small changes in calorie intake or expenditure do not accumulate indefinitely. Changes in body mass eventually cancel out the change in calorie intake or burning.

• Myth 2: Setting realistic goals in obesity treatment is important. Otherwise patients become frustrated and lose less weight.

Fact: Some data suggest that people do better with more ambitious goals.

• Myth 3: Gradually losing weight is better than quickly losing pounds. Quick weight losses are more likely to be regained.

Fact: People who lose more weight rapidly are more likely to weigh less, even after several years.

• Myth 4: Patients who feel "ready" to lose weight are more likely to make the required lifestyle changes. Health-care professionals therefore need to measure each patient'sdiet readiness.

Fact: Among those who seek weight-loss treatment, evidence suggests that assessing readiness neither predicts weight loss nor helps to make it happen.

• Myth 5: Physical education classes, in their current form, play an important role in reducing and preventing childhood obesity.

Fact: Physical education, as typically provided, does not appear to counter obesity.

• Myth 6: Breastfeeding protects the breastfed offspring against future obesity.

Fact: Breastfeeding has many benefits for mother and child, but the data do not show that it protects against obesity.

• Myth 7: One episode of sex can burn up to 300 calories per person.

Fact: It may be closer to one-twentieth of that on average, and not much more than sitting on the couch.

In addition to busting myths, the researchers also found six "presumptions" that they say are widely believed but need more studies before drawing conclusions about weight gain.

The report also says that these widely accepted ideas are just as likely to be false as true:

* Eating breakfast instead of skipping it will help prevent obesity.

* Long-term eating and exercise habits are set in early childhood.

* Regardless of what else you do, eating more fruits and vegetables will lead to weight loss (or less weight gain).

* Yo-yo dieting will take months or years off your life.

* Snacking will make you gain weight.

* The availability of sidewalks, parks and other aspects of the "built environment" influence the prevalence of obesity.