Many widely held beliefs about obesity and weight loss have no scientific basis.
According to the authors of “Myths, Presumptions, and Facts about Obesity,” published in NEJM, there are many beliefs about obesity that persist in the absence of supporting scientific evidence (which they refer to as “presumptions”). Still other beliefs persist despite contradicting evidence (“myths”). It is in the interest of clinicians and patients alike to stymie the spread of obesity-related falsehoods and half-truths because “promulgation of unsupported beliefs may yield poorly informed policy decisions, inaccurate clinical and public health recommendations, and an unproductive allocation of research resources and may divert attention away from useful, evidence-based information.”
Using “Internet searches of popular media and scientific literature,” the authors identified seven obesity-related myths “concerning the effects of small sustained increases in energy intake or expenditure, establishment of realistic goals for weight loss, rapid weight loss, weight-loss readiness, physical-education classes, breast-feeding, and energy expended during sexual activity.” They also identified “six presumptions about the purported effects of regularly eating breakfast, early childhood experiences, eating fruits and vegetables, weight cycling, snacking, and the built (i.e., human-made) environment.”
They also identified “nine evidence-supported facts that are relevant for the formulation of sound public health, policy, or clinical recommendations.”
A news release from the University of Alabama at Birmingham, where lead study author David Allison, PhD, is associate dean for science in the School of Public Health, listed the seven obesity-related myths identified in the study, explained with “implications for public health, policy and clinical recommendations:”
Myth: 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: 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: 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: 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’s diet 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: 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: 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: One episode of sex can burn up to 300 Kcals per person.
Fact: It may be closer to one-twentieth of that on average, and not much more than sitting on the couch.