7 true or false questions: How much do you know about weight loss?

(part 1 in a series)

Seven questions for you today. Score a perfect 7 and we’ll call you . . . doctor of medicine.  Miss all 7 and we’ll call you . . . less often for advice.  The questions are drawn from an exhaustive analysis published earlier this year in The New England Journal of Medicine (the title of the report: “Myths, Presumptions and Facts about Obesity”).  They scoured the popular literature to evaluate dozens of notions about weight loss. Their central question: are these notions true?  You’re about to find out.

Pencils up, here we go:

Lifestyle changes and long-term weight loss

True or False?  “Small sustained changes in energy intake or expenditure will produce large, long-term weight changes.”  Answer: False.

The commonly held notion – that small sustained lifestyle modifications will yield long-term weight loss – simply doesn’t hold up.  The New England Journal report examined the half-century-old rule “which equates a weight alteration of 1 lb to a 3500 calorie cumulative deficit or increment.” However that rule, according to the report, is “derived from short-term experiments predominately performed in men on very-low-energy diets (under 800 calories per day). Recent studies have shown that individual variability affects changes in body composition in response to changes in energy intake and expenditure, with analyses predicting substantially smaller changes in weight . . . than the 3500 calorie rule does.”

Sexual activity and energy expenditure

True or False? “A bout of sexual activity burns 100-300 calories for each participant.”  Answer: False.

According to the New England Journal report: “A man weighing 154 lbs. would . . . expend approximately 3.5 calories per minute during a stimulation and orgasm session. This level of expenditure is similar to that achieved by walking at a moderate pace (approximately 2.5 miles per hour). Given that the average bout of sexual activity lasts about 6 minutes, a man in his early-to-mid-30s might expend approximately 21 calories during sexual intercourse.” The report adds that watching TV for six minutes would burn seven calories, so “the incremental benefit” is just 14 calories.

Rate of weight loss

True or False? “Large, rapid weight loss is associated with poorer long-term weight loss outcomes, as compared with slow, gradual weight loss.”  Answer: False.

What the research shows: “Within weight-loss trials, more rapid and greater initial weight loss has been associated with lower body weight at the end of long-term follow-up” (16.1% of body weight loss vs. 9.7% with low-energy diets).

Breast-feeding and obesity

True or false? “Breast feeding is protective against obesity.” Answer: False.

Said the New England Journal report: “. . . a randomized controlled trial involving more than 13,000 children who were followed for more than 6 years provided no compelling evidence of an effect of breast-feeding on obesity.” These results stand in opposition to a World Health Organization report that concluded: “Persons who were breast-fed as infants are less likely to be obese later in life.” But the New England Journal explains that the WHO, after its report came out, acknowledged publication bias, rendering the results unsound.  Nonetheless, the report did acknowledge: “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.”

Setting realistic weight-loss goals
True or False?  “Setting realistic goals for weight loss is important, because otherwise patients will become frustrated and lose less weight.” Answer: False.

Apparently, there is no consistent link “between ambitious goals and progress completion or weight loss.” In fact, the New England Journal report cites several studies which found that more ambitious goals sometimes led to greater weight loss.   In two noteworthy studies, patients changed their goals from “unrealistic” to “realistic,” yet the change failed to improve their overall weight loss.

Diet readiness

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

The question at hand – how ready is the patient, psychologically, to undertake a weight-loss program?  The widely held belief is that unless a patient is ready to go (truly ready), long-term success will be jeopardized.  According to the New England Journal report: “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.” The authors acknowledge the obvious: “People voluntarily choosing to enter weight-loss programs are, by definition, at least minimally ready to engage in the behaviors required to lose weight.”

Important of Physical Education classes

True or False? “Physical-education classes, in their current form, play an important role in reducing or preventing childhood obesity.”  Answer: False.

A sad, but not entirely unexpected, finding.  Explained the New England Journal report: “Findings in three studies that focused on expanded time in physical education indicated that even though there was an increase in the number of days children attended physical-education classes, the effects on body-mass index were inconsistent across sexes and age groups.” The report adds: “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. Whether that level is plausibly achievable in conventional school settings is unknown. . . . ”

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