Elizabeth A. Thomas

The effectiveness of breakfast recommendations on weight loss: a randomized controlled trial

BACKGROUNDnBreakfast is associated with lower body weight in observational studies. Public health authorities commonly recommend breakfast consumption to reduce obesity, but the effectiveness of adopting these recommendations for reducing body weight is unknown.nnnOBJECTIVEnWe tested the relative effectiveness of a recommendation to eat or skip breakfast on weight loss in adults trying to lose weight in a free-living setting.nnnDESIGNnWe conducted a multisite, 16-wk, 3-parallel-arm randomized controlled trial in otherwise healthy overweight and obese adults [body mass index (in kg/m²) between 25 and 40] aged 20-65 y. Our primary outcome was weight change. We compared weight change in a control group with weight loss in experimental groups told to eat breakfast or to skip breakfast [no breakfast (NB)]. Randomization was stratified by prerandomization breakfast eating habits. A total of 309 participants were randomly assigned.nnnRESULTSnA total of 283 of the 309 participants who were randomly assigned completed the intervention. Treatment assignment did not have a significant effect on weight loss, and there was no interaction between initial breakfast eating status and treatment. Among skippers, mean (±SD) baseline weight-, age-, sex-, site-, and race-adjusted weight changes were -0.71 ± 1.16, -0.76 ± 1.26, and -0.61 ± 1.18 kg for the control, breakfast, and NB groups, respectively. Among breakfast consumers, mean (±SD) baseline weight-, age-, sex-, site-, and race-adjusted weight changes were -0.53 ± 1.16, -0.59 ± 1.06, and -0.71 ± 1.17 kg for the control, breakfast, and NB groups, respectively. Self-reported compliance with the recommendation was 93.6% for the breakfast group and 92.4% for the NB group.nnnCONCLUSIONSnA recommendation to eat or skip breakfast for weight loss was effective at changing self-reported breakfast eating habits, but contrary to widely espoused views this had no discernable effect on weight loss in free-living adults who were attempting to lose weight.

Differences in the neuronal response to food in obesity-resistant as compared to obesity-prone individuals.

Despite living in an obesogenic environment, some individuals maintain a thin phenotype compared to the majority who are at risk for weight gain and obesity. Understanding how these different phenotypes regulate energy intake is critical. The objective of this study was to examine the differences in neuronal response to visual food cues in adults recruited as either obesity-resistant (OR) or obesity-prone (OP) based on self-identification, BMI, and personal/family weight history. 25 OR and 28 OP individuals were studied after 4 days of eucaloric energy intake. Functional magnetic resonance imaging (fMRI) was performed in the fasted and acute fed states (30 min after a test meal) while subjects viewed images of foods of high hedonic value and neutral non-food objects. Measures of appetite using visual analog scales were performed before and every 30 min after the test meal for 3 h. In the fasted state, food as compared to nonfood images elicited significant response in the insula, somatosensory cortex, parietal cortex, and visual cortex in both OR and OP. The acute fed state resulted in significant attenuation of these and other brain areas in the OR but not OP individuals. Furthermore, OP as compared to OR individuals showed greater activation of medial and anterior prefrontal cortex (PFC) in response to the test meal. Adjusting for fat mass did not impact these results. Attenuation of insula/PFC response to food images in the fed state was associated with greater reductions in hunger. These findings suggest that individuals prone to weight gain and obesity have altered neuronal responses to food cues in brain regions known to be important in energy intake regulation. These altered responses may represent an important mechanism contributing to excess energy intake and risk for obesity.

Brain structure predicts risk for obesity.

The neurobiology of obesity is poorly understood. Here we report findings of a study designed to examine the differences in brain regional gray matter volume in adults recruited as either Obese Prone or Obese Resistant based on self-identification, body mass index, and personal/family weight history. Magnetic resonance imaging was performed in 28 Obese Prone (14 male, 14 female) and 25 Obese Resistant (13 male, 12 female) healthy adults. Voxel-based morphometry was used to identify gray matter volume differences between groups. Gray matter volume was found to be lower in the insula, medial orbitofrontal cortex and cerebellum in Obese Prone, as compared to Obese Resistant individuals. Adjusting for body fat mass did not impact these results. Insula gray matter volume was negatively correlated with leptin concentration and measures of hunger. These findings suggest that individuals at risk for weight gain have structural differences in brain regions known to be important in energy intake regulation, and that these differences, particularly in the insula, may be related to leptin.

Usual breakfast eating habits affect response to breakfast skipping in overweight women.

This randomized, cross‐over trial was designed to investigate the metabolic and appetitive responses to skipping breakfast in overweight women who were habitual breakfast Eaters or Skippers.

Eating-related Behaviors and Appetite During Energy Imbalance in Obese-Prone and Obese-Resistant Individuals

While the majority of Americans are now overweight, some individuals maintain their weight with minimal effort. This study investigated behavioral differences between 58 individuals recruited as either obese-resistant (OR) or obese-prone (OP) based on self-identification, BMI, and personal/family weight history. Subjects were studied during Eucaloric (EU), Overfed (OF), and Underfed (UF) phases which included a run-in diet, 1 day intervention diet, and a study day. At baseline, subjects completed the Three Factor Eating Questionnaire (TFEQ) and Power of Food Scale (PFS). On the study day, ratings of appetite, food appeal and desire, and food cravings were performed in response to a breakfast shake. OF resulted in reduced hunger and food desire while UF resulted in increased hunger and food appeal and desire. While hunger did not differ between groups, OP had higher scores for TFEQ measures (hunger, restraint and disinhibition), higher hedonic hunger as measured by the PFS, and greater food cravings and ratings of food appeal and desire. These results suggest that subjective hunger and desire for food change significantly after only one day of over- or underfeeding. Additionally, we found several behavioral differences between groups that are likely to promote weight gain over time in the OP.

The Effects of Energy Balance, Obesity-Proneness and Sex on the Neuronal Response to Sweet Taste

We have previously shown that propensity for weight gain, energy balance state and sex are important determinants of the neuronal response to visual food cues. It is not clear, though, whether these factors also impact the neuronal response to taste. The objective of this study was to examine the neuronal response to sweet taste during energy imbalance in men and women recruited to be obesity-prone (OP) or obesity-resistant (OR). OP (13 men and 12 women) and OR (12 men and 12 women) subjects were studied after 1 day of eucaloric, overfed and underfed conditions in a randomized crossover design. On each test day, fMRI was performed in the respective acute fed state while subjects received in random order 60 trials each of 1M sucrose solution (SU), or artificial saliva (AS) following a visual cue predicting the taste. The neuronal response to SU versus AS expectation was significantly greater in the amygdala, orbitofrontal cortex, putamen and insula in OR versus OP; SU receipt was not different between groups. There were also sex-based differences with men having greater neuronal response to SU versus AS receipt in the caudate than women. The results, however, were not impacted by the state of energy balance. In summary, response to expectation but not receipt of basic sweet taste was different in OR compared to OP, highlighting the importance of learning and conditioning in the propensity to gain weight. Response to sucrose taste receipt was stronger in men than women, raising questions about the effect of sex hormones on brain response to food.

Greater hunger and less restraint predict weight loss success with phentermine treatment

Phentermine is thought to cause weight loss through a reduction in hunger. It was hypothesized that higher hunger ratings would predict greater weight loss with phentermine.

Propensity to Obesity Impacts the Neuronal Response to Energy Imbalance

The mechanisms responsible for the propensity to gain weight or remain normal weight are poorly understood. The objective of this study was to study the neuronal response to visual food cues during short-term energy imbalance in healthy adults recruited as obesity-resistant (OR) or obesity-prone (OP) based on self-identification, body mass index, and personal/family weight history. Twenty-five OR and 28 OP subjects were studied in underfed (UF) and overfed (OF) as compared to eucaloric (EU) conditions in a randomized crossover design. Each study phase included a 3-day run-in diet, 1u2009day of controlled feeding (basal energy needs for EU, 40% above/below basal energy needs for OF/UF), and a test day. On the test day, fMRI was performed in the acute fed stated (30u2009min after a test meal) while subjects viewed images of foods of high hedonic value and neutral non-food objects. Measures of appetite and hormones were also performed before and every 30u2009min after the test meal. UF was associated with significantly increased activation of insula, somatosensory cortex, inferior and medial prefrontal cortex (PFC), parahippocampus, precuneus, cingulate, and visual cortex in OR. However, UF had no impact in OP. As a result, UF was associated with significantly greater activation, specifically in the insula, inferior PFC, and somatosensory cortex in OR as compared to OP. While OF was overall associated with reduced activation of inferior visual cortex, no group interaction was observed with OF. In summary, these findings suggest that individuals resistant to weight gain and obesity are more sensitive to short-term energy imbalance, particularly with UF, than those prone to weight gain. The inability to sense or adapt to changes in energy balance may represent an important mechanism contributing to excess energy intake and risk for obesity.

Greater Reward-Related Neuronal Response to Hedonic Foods in Women Compared with Men: Sex Differences in Neuronal Response to Food

The current study aimed to identify how sex influences neurobiological responses to food cues, particularly those related to hedonic eating, and how this relates to obesity propensity, using functional magnetic resonance imaging (fMRI).