Straight talk on diets

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Ever heard the one about how many calories you can burn off having sex? Hundreds of calories, right? Not even close. It’s really about 14 calories. That’s right, 14 calories.

That’s only one of the popular myths out there about obesity and how you can lose weight. And now a team of researchers, including Dr. Steven Heymsfield of the Pennington Biomedical Research Center, is setting the record straight.

In a recent issue of the New England Journal of Medicine, the researchers analyzed articles in both the scientific and the popular press to separate myths from facts.

“Obesity is a serious national problem that requires evidence-based findings upon which to base public policy and patient recommendations,” says Heymsfield. “This study sets the baseline for what is founded on fact and myth.”

Here’s what they discovered:

The myth: One episode of sex burns 100 to 300 calories for each participant.

The truth: 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.

The myth: Small sustained changes in energy (caloric) intake or expenditure will produce large long-term weight changes.

The truth: This belief suggests 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 50 pounds, when the true weight loss is only about 10 pounds.

The myth: Setting realistic goals for weight loss is important, because otherwise patients will become frustrated and lose less weight.

The truth: No data 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.

The myth: Large, rapid weight loss is associated with poorer long-term weight loss outcomes, as compared with slow, gradual weight loss.

The truth: 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 (calorie) diets and low-energy diets (800 to 1200 calories per day) over more than one year.

The myth: It is important to assess “diet readiness” in order to help patients who request weight loss treatment.

The truth: 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.

The myth: Physical-education classes, in their current form, play an important role in reducing or preventing childhood obesity.

The truth: 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.

The myth: Breastfeeding is protective against obesity.

The truth: 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.

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