Reducing an entrée portion size does not affect the amount of dessert consumed.

BACKGROUND: Increasing portion size has been shown to increase energy intake. However, little is known about the effect of reducing portion size on subsequent consumption and the consequent energy intake. OBJECTIVE: The purpose of this study was to examine the effect of decreasing portion size of an entrée on the amount of dessert consumed as a following course. METHODS: A total of 81 participants were instructed to consume a lunch entrée and dessert ad libitum. The participants were given the same entrée and dessert on the same day of the week for four consecutive weeks. However, the entrée was reduced to 90%, 85%, 80%, and 75% of the amount they consumed in the first week of the study. Participants were randomized into four groups and were served the reduced entrée according to a Latin square design. Dessert was consumed ad libitum. In addition, subjects' hunger and satiety levels were assessed before the entrée, after the entrée, and after dessert. RESULTS: Reducing portion size had no effect on the amount of dessert consumed despite the finding that measures of hunger and satiety indicated that participants experienced increased hunger at 80% and 75% portion reductions. CONCLUSIONS: Reduction in the portion size of an entrée by up to 25% did not increase the amount of dessert consumed, despite an increase in perceived hunger at lower portion sizes. Further investigation is needed to study how much further portion size could be reduced with a sustained decrease in energy intake without compensation, as well as to examine potential interventions for portion control that could reduce daily energy intake.

Quantifying the imprecision of energy intake of humans to compensate for imposed energetic errors: A challenge to the physiological control of human food intake.

To assess the precision of the biological control of energy intake we performed a systematic review of studies that measured acute changes in human food intake in response to energetic errors. The imposed errors were grouped into the following categories of studies: alternate day fasting, changes in diet composition, exercise, meal skipping, overfeeding, energy substitutes, underfeeding and changes in portion size. Seven hundred thirty-nine studies published between 1980 and 2017 were identified from which the data from 592 groups from 200 studies were extracted and subjected to analysis consisting of a total of 13,203 participants. For each category of imposing an energetic error, an Energetic Error was calculated as (Observed Mean Energy Intake - Expected Mean Energy Intake)/Expected Mean Energy Intake. In no category of studies was the Energetic Error equal to zero. In studies where participants were expected to increase energy intake, the increase was not sufficient to overcome the deficit. Similarly, in studies where a reduction in energy intake was expected, the reduction was insufficient to restore energy balance to zero. The average energetic error resulting from imposed energetic challenges is about twenty-four percent, a value sufficiently large to account for the increase in body weight observed in the U.S. population over the past 50 years.

Lack of negative autocorrelations of daily food intake on successive days challenges the concept of the regulation of body weight in humans.

According to most theories, the amount of food consumed on one day should be negatively related to intake on subsequent days. Several studies have observed such a negative correlation between the amount consumed on one day and the amount consumed two to four days later. The present study attempted to replicate this observation by re-examining data from a previous study where all food ingested over a 30-day observation period was measured. Nine male and seven female participants received a vegan diet prepared, dispensed, and measured in a metabolic unit. Autocorrelations were performed on total food intake consume on one day and that consumed one to five days later. A significant positive correlation was detected between the weight of food eaten on one day and on the amount consumed on the following day (r = 0.29, 95% CI [0.37, 0.20]). No correlation was found between weights of food consumed on one day and up to twelve days later (r = 0.09, 95% CI [0.24, -0.06]), (r = 0.11, 95% CI [0.26, -0.0.26]) (r = 0.02, 95% CI [0.15, -0.7]) (r = -0.08, 95% CI [0.11, -0.09]). The same positive correlation with the previous day's intake was observed at the succeeding breakfast but not at either lunch or dinner. However, the participants underestimated their daily energy need resulting in a small, but statistically significant weight loss. Daily food intake increased slightly (13 g/day), but significantly, across the 30-day period. An analysis of the previous studies revealed that the negative correlations observed by others was caused by a statistical artifact resulting from normalizing data before testing for the correlations. These results, when combined with the published literature, indicate that there is little evidence that humans precisely compensate for the previous day's intake by altering the amount consumed on subsequent days. Moreover, the small but persistent increase in food intake suggests that physiological mechanisms that affect food intake operate more subtly and over much longer periods of time than the meal or even total daily intake.

Weighing the Evidence of Common Beliefs in Obesity Research.

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 10 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; breastfeeding; 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 the obesity domain.

Does measuring body weight impact subsequent response to eating behavior questions?

OBJECTIVES: If being weighed impacts perceptions of eating behavior, it is important that the order of questionnaires and weighing be considered in research and practice. A quasi-experimental study was performed to examine whether being weighed immediately prior to completing a questionnaire affects responses to eating behavior questions. It was hypothesized that being weighed would serve as a priming stimulus and increase measures of dietary restraint, disinhibition, and hunger. METHODS: Trained researchers collected a sample of volunteers (n = 355) in 8 locations in the United States on two Saturdays in the summer of 2011. Half of the participants were weighed immediately prior to completing the Three Factor Eating Questionnaire (TFEQ), with the remaining half weighed immediately after TFEQ completion. RESULTS: A priori hypotheses were not supported despite replicating known relationships between weight, dietary restraint and disinhibition. Results indicated that being weighed first produced a difference in differences on disinhibition scores between low restraint score (95% CI = 4.65-6.02) and high restraint score (95% CI = 6.11-7.57) compared to being weighed after questionnaire completion (p = 0.003). However, this relationship was not significant when modeling restraint as a continuous variable, questioning the use of dichotomization. CONCLUSIONS: Being weighed is unlikely to be a strong enough prime to significantly change scores on eating behavior questionnaires for everyone, but may allow differences in restraint status to become more evident. Researchers assessing dietary restraint should be wary of the possibility of producing different results when treating restraint as continuous or dichotomous, which could lead to different interpretations.

A nudge in a healthy direction. The effect of nutrition labels on food purchasing behaviors in university dining facilities.

BACKGROUND: Despite legislation that requires restaurants to post nutritional labels on their products or menu items, the scientific literature provides inconsistent support for the idea that adding labels to foods will change buying patterns. Lack of success of previous research may be that sample sizes have been too small and durations of studies too short. OBJECTIVE: To assess the effect of nutrition labeling on pre-packaged food purchases in university dining facilities. DESIGN: Weekly sales data for a sample of pre-packaged food items were obtained and analyzed, spanning three semesters before and three semesters after nutritional labels were introduced on to the sample of foods. The labels summarized caloric content and nutrient composition information. Mean nutrient composition purchased were calculated for the sample of foods. Labeled food items were categorized as high-calorie, low-calorie, high-fat, or low-fat foods and analyzed for change as a function of the introduction of the labels. SETTING: Data were obtained from all retail dining units located at Cornell University, Ithaca, NY where the pre-packaged food items were sold. RESULTS: Results indicated that the introduction of food labels resulted in a 7% reduction of the mean total kcals purchased per week (p < 0.001) from the labeled foods. Total fat purchased per week were also reduced by 7% (p < 0.001). Percent of sales from "low-calorie" and "low-fat" foods (p < 0.001) increased, while percent of sales from "high-calorie" and "high-fat" foods decreased (p < 0.001). CONCLUSIONS: The results suggest that nutrition labels on pre-packaged foods in a large university dining hall produces a small but significant reduction of labeled high calorie and high fat foods purchased and an increase in low calorie, low fat foods.

Lack of compensation of energy intake explains the success of alternate day feeding to produce weight loss.

BACKGROUND AND AIMS: This study was designed to obtain daily weighed food intake of participants engaged in Alternate Day Feeding (ADF). Prior ADF studies have used self-reported food intake, a method that has received criticism for its limited accuracy. SUBJECTS AND METHODS: Forty-nine university students received academic credit for participating in the study. Following a 10-day baseline period, participants underwent ADF for the next 8 days. Restricted daily intake to ∼ 75% of baseline food intake levels was followed by ad libitum intake on alternate days. Food intake was weighed before and after each meal. Daily body weight was also tracked. INTERVENTION: After the baseline period, participants underwent 8 days of ADF during which they consumed ∼ 75% of baseline energy intake by weight followed by ad libitum intake on alternate days. The trial concluded with 2 additional days of ad libitum feeding, for a total study duration of 10 days. RESULTS: Daily food intake was constant during the baseline period (slope = -0.93 g/d, p = 0.56), and did not differ significantly (995 g (95% CI [752, 1198]) from the total consumed on ad libitum ADF days (951 g (95% CI [777, 1227]). Intake on ad libitum days did not show a trend to increase during the intervention. Body weight declined significantly during ADF. CONCLUSIONS: ADF produces significant weight loss because food intake does not increase on ad libitum feeding days to compensate for reduced intake on restricted energy days. Data are consistent with prior work that suggests humans do not fully compensate for imposed deficits in energy intake.

Free will and the obesity epidemic.

The increase in body weight in the USA over the past several decades is now commonly referred to as the 'obesity epidemic'. An empirical analysis of the literature suggests that the increased weight can be accounted for by an increase in food intake. The solution to the obesity epidemic, therefore, must centre on a reduction in food consumption, a position well accepted by the American population who think that they, as individuals, are responsible for their adiposity by holding the belief that the decision as to what and how much to eat is determined by their own free will. The evidence demonstrates, however, that this is not true. Variables such as portion size, variety of foods offered, fat content of the diet, the number of people eating, the location where eating occurs and even watching food advertisements act as 'food primes' causing individuals to increase their energy intake. Despite the plethora of diets, weight-loss clubs, drugs and mechanical devices available to facilitate weight loss, once treatment is terminated and people return to the 'free' environment, their weight returns to pre-treatment levels. Only when individuals are protected from environmental variables by gastric surgery or limited to consume only portion-controlled meals can they successfully maintain a reduced weight. Combining the technique of daily weight monitoring with accepting that our eating behaviour is not determined totally by our free choice, we may be able to curb the obesity epidemic.

The Rise and Fall of Physiological Theories of the Control of Human Eating Behavior.

Kuhns was the first to suggest that theories in science do not develop in small increments but rather in major leaps to paradigms that examine the same question through very different perspectives. Theories on the mechanism responsible for control of human food intake fall into Kuhn's description. This article describes how the two major theories of the control of food intake in humans, the Glucostatic Theory, and the Lipostatic Theory, showed initial promise as explanations, but later deteriorated with the slow accumulation experimental data. The locus of theories considered eating behavior as a part of physiological system that regulates the storage of energy on the body. We challenge this fundamental belief with data which suggests that we must be ready to accept a major change in the way we think about eating behavior if we are ever to decrease the prevalence of obesity.

Losing weight without dieting. Use of commercial foods as meal replacements for lunch produces an extended energy deficit.

High-protein liquid meal replacements have proven to be effective in reducing caloric intake and body weight. Recently, substituting high fiber breakfast cereals for the more expensive high-protein drinks has been found to be equally effective to reduce weight. The following study tested the hypothesis that the mechanism responsible for the reduced intake was not the dietary composition of the meal replacement, but the controlled portion sized meals. Seventeen volunteers ate all of their meals and snacks from foods provided by the research unit from Monday to Friday for five consecutive weeks. For the first week, all participants selected their food from a buffet where each food was weighed before and after eating. For the next two weeks, half of the group selected their lunch by choosing one food from a selection of six commercially available portion controlled foods. They could eat as much as they wished at other meals or snacks. For final weeks four and five, the conditions were reversed for the two groups. Consuming the portion controlled lunches resulted in about a 250 kcal reduction in energy intake. More importantly, no sign of caloric compensation was evident across the 10 days of testing, an observation substantiated by a significant loss of body weight. The results suggest that the mere substitution of one smaller portioned meal each day is sufficient to cause reduction in daily energy intake and a significant amount of weight.

Methodological Challenges in Estimating the Lifetime Medical Care Cost Externality of Obesity.

There is a great deal of variability in estimates of the lifetime medical care cost externality of obesity, partly due to a lack of transparency in the methodology behind these cost models. Several important factors must be considered in producing the best possible estimate, including age-related weight gain, differential life expectancy, identifiability, and cost model selection. In particular, age-related weight gain represents an important new component to recent cost estimates. Without accounting for age-related weight gain, a study relies on the untenable assumption that people remain the same weight throughout their lives, leading to a fundamental misunderstanding of the evolution and development of the obesity crisis. This study seeks to inform future researchers on the best methods and data available both to estimate age-related weight gain and to accurately and consistently estimate obesity's lifetime external medical care costs. This should help both to create a more standardized approach to cost estimation as well as encourage more transparency between all parties interested in the question of obesity's lifetime cost and, ultimately, evaluating the benefits and costs of interventions targeting obesity at various points in the life course.

The daily Self-Weighing for Obesity Management in Primary Care Study: Rationale, design and methodology.

Background Daily self-weighing (DSW) may be an effective harm-reduction intervention to disrupt continued weight gain. Self-Weighing for Obesity Management in Primary Care (SWOP) is a 24-month randomized controlled trial in 400 adults with obesity (BMI: kg/m2 ≥ 30) receiving primary care through a clinical network affiliated with an academic medical center. Objective To test DSW as a potentially scalable way to deter age-related weight gain among primary care patients with obesity. Methods Randomized-controlled trial with two conditions: DSW (instruction to weigh daily and provision of a web-enabled digital scale with graphical weight feedback) or Standard Care (receive a monetary gift card equivalent to value of the scale). Both groups receive standardized weight management educational material. SWOP will test the causal effect of assignment to DSW (Aim 1) and adherence to DSW (Aim 2) on weight (primary outcome) and adoption of weight management practices (secondary outcomes), as well as evaluate the cost-effectiveness of DSW compared to standard care (Aim 3). Findings may inform clinical guidelines for weight management by providing evidence that DSW attenuates continued age-related weight gain among adults with obesity. This trial is registered with ClinicalTrials.gov (NCT04044794).

Self-Weighing and Visual Feedback Facilitates Self-Directed Learning in Adults Who Are Overweight and Obese.

OBJECTIVE: Understanding how and why self-weighing works for some individuals but not others in weight management is vital. This study investigated how self-weighing and tracking of weight using a Web site facilitated a self-directed learning process in overweight or obese adults interested in losing weight. DESIGN: Semistructured interviews with study completers (n = 47) and voluntary withdrawals (n = 10) about their experience after 6 and 12 months of using the program or when they withdrew. ANALYSIS: Qualitative, guided by self-directed learning theory. RESULTS: Although both completers and those who withdrew engaged in self-directed learning, often exemplifying the same concepts (eg, instrumental learning), experiences described a positive sense of control over weight in completers and a lack of sense of control in those who withdrew. CONCLUSIONS AND IMPLICATIONS: Overall, it seemed that frequent self-weighing and visual feedback of body weight over time facilitated a self-directed learning process in both completers and those who withdrew. This research provides a rich understanding of how adults use self-weighing to facilitate self-directed learning for weight loss. Future studies assessing how self-weighing and visual displays of weight facilitate a self-directed learning process in diverse populations and age groups are necessary to better understand how self-weighing works and for whom self-weighing is beneficial.

Predicted Lifetime Third-Party Costs of Obesity for Black and White Adolescents with Race-Specific Age-Related Weight Gain.

OBJECTIVE: There exists enormous variation in estimates of the lifetime cost of adolescent obesity by race. To justify policy measures to reduce obesity rates nationally in this demographic, the costs of obesity in late adolescence must first be discerned. Although several researchers have sought to quantify obesity's true cost, none has accounted for race-specific age-related weight gain, a vital component in producing an accurate estimate. METHODS: This paper employs a Markov model of BMI category state changes separately for black and white males and females from age 18 to 75 applied to updated estimates of obesity's costs and effect on mortality to quantify the median lifetime cost of obesity at age 18. RESULTS: This study found lower lifetime costs than previously, largely because of the dramatic gain in weight among normal-weight individuals, particularly black males, that occurs in early adulthood. CONCLUSIONS: A substantial portion of obesity's prevalence, and therefore cost, for black males and females comes from age-related weight gain in early adulthood. This speaks to the persistent threat of obesity beyond adolescence for this demographic, and further research should focus on whether policy can modify the behaviors and environment through which and in which this sharp increase in weight occurs.

Succimer chelation improves learning, attention, and arousal regulation in lead-exposed rats but produces lasting cognitive impairment in the absence of lead exposure.

BACKGROUND: There is growing pressure for clinicians to prescribe chelation therapy at only slightly elevated blood lead levels. However, very few studies have evaluated whether chelation improves cognitive outcomes in Pb-exposed children, or whether these agents have adverse effects that may affect brain development in the absence of Pb exposure. OBJECTIVES: The present study was designed to answer these questions, using a rodent model of early childhood Pb exposure and treatment with succimer, a widely used chelating agent for the treatment of Pb poisoning. RESULTS: Pb exposure produced lasting impairments in learning, attention, inhibitory control, and arousal regulation, paralleling the areas of dysfunction seen in Pb-exposed children. Succimer treatment of the Pb-exposed rats significantly improved learning, attention, and arousal regulation, although the efficacy of the treatment varied as a function of the Pb exposure level and the specific functional deficit. In contrast, succimer treatment of rats not previously exposed to Pb produced lasting and pervasive cognitive and affective dysfunction comparable in magnitude to that produced by the higher Pb exposure regimen. CONCLUSIONS: These are the first data, to our knowledge, to show that treatment with any chelating agent can alleviate cognitive deficits due to Pb exposure. These findings suggest that it may be possible to identify a succimer treatment protocol that improves cognitive outcomes in Pb-exposed children. However, they also suggest that succimer treatment should be strongly discouraged for children who do not have elevated tissue levels of Pb or other heavy metals.

Succimer chelation normalizes reactivity to reward omission and errors in lead-exposed rats.

This study evaluated the efficacy of a 3-week course of succimer treatment to alleviate behavioral deficits in rats exposed to lead (Pb) for the first 4 weeks of life. A 3 x 2 factorial design was used: three levels of lead exposure (No Pb, Moderate, and High Pb) and two levels of chelation (succimer or vehicle). Behavioral testing was conducted following chelation therapy, from 2 to 9 months of age; this report presents the results of two of the administered tasks: (1) a conditional olfactory discrimination task (baseline task), and (2) a conditional olfactory discrimination task with periodic reward omission on some correct trials (RO task). In the RO task, the performance disruption produced by committing an error on the previous trial was significantly greater for both unchelated lead-exposed groups than for controls. The High Pb rats were also more sensitive to reward omission than controls, providing converging evidence for impaired regulation of arousal or emotion. Importantly, succimer treatment was effective in normalizing the heightened reactivity of the lead-exposed animals to both errors and reward omission. In addition, non-lead-exposed rats that were treated with succimer tended to be more affected by a prior error than controls in their latency to respond on post-error trials. In sum, these findings provide new evidence that succimer chelation can significantly lessen the lasting neurobehavioral dysfunction produced by early lead exposure, but also suggest that there may be risks of administering the drug to individuals without elevated blood lead levels.

Three-Year Follow-Up of Participants from a Self-Weighing Randomized Controlled Trial.

Frequent self-weighing is associated with weight loss maintenance. Several years ago, we investigated frequent self-weighing's effect on weight loss and found the participants lost a significant amount of weight. Three years after this trial's end, participants were contacted for an update on their weight and self-weighing frequency. Weight change and self-weighing frequency since the end of the study were assessed. We hypothesized that participants who maintained frequent self-weighing behavior would have maintained their weight loss. Out of 98 participants enrolled in the RCT, 37% (n = 36) participated in this follow-up study. Total weight loss during the trial for the follow-up participants was 12.7 ± 19.4 lbs (p < 0.001). Three years after intervention, participants regained 0.9 ± 4.34 lbs, a value that was not statistically different from zero (p = 0.75). This did not differ by gender (p = 0.655). Over 75% of these participants continued to weigh themselves at least once a week. Frequent self-weighing may be an effective, low-cost strategy for weight loss maintenance. Future research should further investigate the role of self-weighing in long-term weight gain prevention.

The non-regulation of food intake in humans: hope for reversing the epidemic of obesity.

Few doubt that human feeding behavior is part of larger biology regulatory system of energy stores, but the extent to which eating behavior is controlled by these biology systems and how much is due to responses to environmental stimuli is presently under debate. The results of a series of studies are presented which have attempted to determine the responsiveness of human feeding behavior to some of the "classic" biological variables that have conventionally been used to argue the biological basis of eating behavior. When humans are challenged with either overfeeding, underfeeding, or alterations of the caloric density of the diet, they fail to demonstrate precise caloric compensation. When challenged with changes in environmental stimuli, on the other hand, humans appear to be very sensitive to changes in portion size, the number of people with whom they eat, the amount that others eat and the variety of foods available. Other more chronic influences demonstrate that body weight appears to change when people move from one area of the world to another, when they enter the college environment, or when they either marry or break up. It is argued that because humans appear to be more responsive to the external environment than internal biological cues, it should be possible to curb or even reverse the epidemic of obesity by changing aspects of the external environment or human interactions with environmental variables rather than changing their internal environment through pharmacology.

Imprecise control of energy intake: absence of a reduction in food intake following overfeeding in young adults.

The objective was to examine the extent to which overfeeding reduces spontaneous food intake in humans. Twelve normal-weight adults participated in the three stage study. During the 14 day baseline period and 21 day recovery period, food intake was consumed ad libitum, beyond a minimum 5 MJ (1200 kcal) basal diet. During the 13 day period of overfeeding, each subject consumed 35% more energy than they consumed at baseline. Overfeeding resulted in a weight gain of 2.3+/-0.37 kg, (p<0.0001), approximately half the weight gain was determined to be fat (1.2+/-0.19 kg, p<0.0001) by underwater densitometry. Following overfeeding, mean daily caloric intake was not significantly suppressed returning immediately to baseline values. Despite normal energy intake, participants lost 1.3+/-0.24 kg of body weight (p<0.0001), of which 0.75+/-0.15 kg (p<0.0001) was fat. These results indicated that (1) the physiological control of eating behavior in humans is not the major mechanism responsible for the recovery of body weight following a period of overfeeding and (2) an increase in energy expenditure of 1.28 MJ (307 kcal)/day or about 14% was required to account for the weight loss following overfeeding.

Frequent Self-Weighing and Visual Feedback for Weight Loss in Overweight Adults.

Evidence has suggested that self-weighing may be beneficial for weight control in adults, but few studies have independently assessed the contribution of this behavior to weight loss. This study experimentally tested daily self-weighing and visual feedback (the Caloric Titration Method (CTM)) as a weight loss and weight loss maintenance intervention over 2 years. 162 overweight individuals were randomized to the CTM intervention or delayed treatment control group. In year 1, weight change was compared between groups, and in year 2, the control group started using the CTM while the intervention group continued using the CTM for maintenance. A significant difference in weight loss over the first year (CTM n = 70; 2.6 ± 5.9 kg versus control n = 65; 0.5 ± 4.4 kg, p = 0.019) was qualified by a group × gender × time interaction (p = 0.002) such that men lost more weight using the CTM. In year 2, the CTM group maintained their weight and the control group lost an amount similar to the intervention group in year 1. Daily self-weighing and visual feedback facilitated a minimal amount of weight loss and maintenance of this loss. Future research investigating characteristics of those who benefit from this type of self-directed intervention is warranted.