Weighing the Evidence of Common Beliefs in Obesity Research

Abstract

Obesity is a topic on which many views are strongly held in the absence of scientific evidence to support those views, and some views are strongly held despite evidence to contradict those views. We refer to the former as “presumptions” and the latter as “myths”. Here we present nine myths and ten presumptions surrounding the effects of rapid weight loss; setting realistic goals in weight loss therapy; stage of change or readiness to lose weight; physical education classes; breast-feeding; daily self-weighing; genetic contribution to obesity; the “Freshman 15”; food deserts; regularly eating (versus skipping) breakfast; eating close to bedtime; eating more fruits and vegetables; weight cycling (i.e. yo-yo dieting); snacking; built environment; reducing screen time in childhood obesity; portion size; participation in family mealtime; and drinking water as a means of weight-loss. For each of these, we describe the belief and present evidence that the belief is widely held or stated, reasons to support the conjecture that the belief might be true, evidence to directly support or refute the belief, and findings from randomized controlled trials, if available. We conclude with a discussion of the implications of these determinations, conjecture on why so many myths and presumptions exist, and suggestions for limiting the spread of these and other unsubstantiated beliefs about obesity domain.

Metabolic Effects of Intermittent Fasting

“…The Chowdhury et al study (22) of skipping breakfast showed no increase in food intake at lunch after the prolonged morning fast and showed no increase in post-lunch appetite. Casazza et al (16) conducted a systematic review of obesity-related beliefs about weight loss, therein stating that evidence was lacking to support the notion that skipping breakfast independently affected obesity. Several of these authors conducted a randomized controlled weight-loss trial comparing breakfast-skipping, breakfast-eating, and control groups, finding that weight loss was not different among the groups (25).…”

Childhood obesity: Current and novel approaches

“…persistent beliefs in the absence of supporting scientific evidence) include examples such as 'regularly eating breakfast protects against obesity', and 'snacking contributes to weight gain and obesity', while myths (i.e. persistent beliefs despite contradictory evidence) includes advice such as 'slow weight loss has greater long-term benefit than rapid weight loss', 'breastfeeding protects against obesity', and even that 'sexual activity burns enough calories to aid weight loss' [32,33]. Even researchers are not immune from this effect and 'white hat bias' in the findings that researchers and/or journal editors/reviewers may subconsciously and selectively promulgate has been a further hindrance to progress [34].…”

Whether Smaller Plates Reduce Consumption Depends on Who's Serving and Who's Looking: A Meta-Analysis

“…In a qualitative review, Casazza et al (2015) concluded that plate size was a "robust driver of self-served portion sizes." Robinson and Matheson (2015) in another qualitative review concluded that "smaller diameter plates [and] bowls" reduce consumption while acknowledging that there were some studies that showed no effect.…”

“…Robinson et al's (2014b) meta-analysis focused on "formally measured or recorded food intake," while Casazza et al (2015) focused on self-served portions. In general, the amount self-served is presumed to mediate the amount consumed (see fig.…”