Research Spotlights: June 2022

A novel weight-loss intervention that targets appetite cues may help with weight loss among adults with overweight and obesity

Overweight and obesity are concerns for many adults in the U.S. Recently published research supported by the NIDDK, NCATS and others, examined the efficacy of a novel, regulation of cues-based weight loss intervention based on behavioral susceptibility theory and designed to target appetitive traits. Although there are many weight loss interventions that show promise, not all interventions work for everyone, and sustaining weight loss after the intervention period continues to be a significant challenge. This heterogenous response to these interventions are likely due different underlying factors that impact an individual’s ability to lose weight and maintain weight loss. The behavioral susceptibility theory posits that genetically determined appetitive traits, such as eating onset driven by food responsiveness and eating offset driven by satiety responsiveness, interact with the current food environment and result in overeating and weight gain. Previous research suggests that both food responsiveness and satiety responsiveness are highly heritable and durable traits that are shaped by environmental and individual level factors.

The researchers conducted a randomized clinical trial, Providing Adult Collaborative Interventions for Ideal Changes (PACIFIC), at the Center for Healthy Eating and Activity Research at the University of California San Diego from December 2015 to December 2019. Adults ages 18 to 65 years with a BMI of 25 to 45 residing in the San Diego area were recruited via radio and online advertisements, ResearchMatch, and referrals from health care practitioners. A total of 271 adults (mean age = 46.97, 81.6% female, 61.95% White) participated in this trial. Briefly, the regulation of cues (ROC) intervention included 4 components: psychoeducation to increase awareness of situations and emotional states, etc. that lead to overeating; experiential learning; coping skills; and self-monitoring. The standard behavioral weight loss (BWL) program involved following a recommended balanced deficit diet based on the US Department of Agriculture’s MyPlate guidelines. Participants in this study were assigned to one of four conditions: 1) a novel intervention focused on helping individuals become aware of and manage situations that lead to overeating (ROC), 2) the novel intervention plus additional behavioral weight loss strategies (ROC+), 2) behavioral weight loss strategies only (BWL), and 4) an active comparator condition that included psychoeducation and mindfulness (AC). Participants in the three active treatment groups were given pedometers and encouraged to monitor physical activity. Participants were assessed at baseline (month 0), mid-treatment (month 6), posttreatment (month 12), 6-month follow-up (month 18), and 12-month follow-up (month 24).

Researchers compared ROC and ROC+ to AC on changes in BMI at mid-treatment, posttreatment, 6-month, and 12-month follow-ups. Notably, among participants with high levels of food cue responsivity, those who received ROC+ sustained greater decreases in weight than those who received AC. Additionally, although participants in the ROC+, BWL, and AC conditions had some weight regain starting at mid-treatment, those in the ROC condition were able to stabilize their weight after the mid-treatment time point. Researchers also compared ROC and ROC+ with BWL on differences in BMI at posttreatment and rate of BMI change during and after treatment. Researchers found that participants in the ROC, ROC+ and BWL conditions had significantly lower BMIs at the end of treatment, and there were no significant different between, ROC, ROC+, and BWL for weight loss at posttreatment or 12-month follow up. There were also no significant differences in rates of change in BMI after treatment ended for ROC or ROC+ compared to AC.

The study findings have some limitations including that the primary outcome measure was BMI and did not include any other metabolic indicators. Additionally, participants only included those interested in treatment, and may not generalize to the population of adults experiencing overweight or obesity.

In summary, this study found that a novel intervention focused on regulation of cues was successful in helping with weight loss among adults with overweight and obesity. The ROC model targets appetitive traits, which is different than existing behavioral weight loss interventions, and may additionally help with weight loss stabilization. Furthermore, this intervention showed particular promise among those with high levels of food responsiveness. This research highlights the need targeted weight loss interventions take multiple factors into account to help address overweight and obesity.

Boutelle KN, Eichen DM, Peterson CB, Strong DR, Kang-Sim DE, Rock CL, Marcus BH. Effect of a Novel Intervention Targeting Appetitive Traits on Body Mass Index Among Adults With Overweight or Obesity: A Randomized Clinical Trial. JAMA Netw Open. 2022 May 2;5(5):e2212354. doi: 10.1001/jamanetworkopen.2022.12354. PMID: 35583870; PMCID: PMC9118075.

Exposure to new objects primes people to learn

During development, we learn to identify commonplace items, such as a table, chair, or a dog, and what category items belong to, such as cats verses dogs, prior to receiving explicit information or teaching. Recent published research supported by the NICHD sought to answer the question of how incidental exposure contributes to category learning. More specifically, they wanted to determine if incidental exposure to categories contributes to category learning by making people “ready-to-learn” categories after briefly receiving explicit teaching.

The investigators conducted five different experiments within this study (n = 438, recruited from Amazon MTurk). In these experiments, participants first took part in an exposure phase in which they played an easy computer game while seeing colorful pictures of unfamiliar creatures. There was no information provided about these creatures during the exposure phase. In the next part of the study, participants went through an explicit learning phase where they were taught that the creatures belonged to two categories, and to identify the category membership of each creature. The researchers then measured how long it took participants to learn the difference between categories A and B. The results showed that the participants who received early exposure to the images of the creatures were quicker to learn how to categorize the different groups of creatures as compared to the non-early exposure participants.

In another experiment, participants played a computer game where the exposure phase involved hearing sounds that were randomly attached to images of the creatures. When the participants heard the same sound played twice in a row, they had to hit a key. The participants who were shown the images of the creatures (category A and B) during the exposure phase learned the differences between them faster during the explicit learning phase than participants who were shown other unrelated images. These results indicate that the exposure to the pictures of the creatures was facilitating these individuals to learn faster later.

To determine if the participants were somehow learning about the creature categorization characteristics during the exposure phase, instead of during the explicit learning phase, the researchers conducted another experiment. In these experiments, the computer game in the exposure phase involved first seeing a creature in the center of the screen and then the participants were then asked to hit certain computer keys if the creature jumped to the left or the right side of the screen as quickly as possible. The participants were not told that one category of creature always jumped to the left and the other always jumped to the right. If they learned this difference between the creatures during this exposure phase, then their response time would be faster than control participants shown unrelated images. Results showed that participants did not respond faster, implying that they did not learn to differentiate between category A and B creatures during the exposure phase of the experiment. Consistent with the previous experiments, participants that received the incidental exposure learned more quickly in the explicit learning part of the experiment as compared to those participants who were exposed to images of unrelated creatures.

In summary, this study found that incidental exposure produces a “ready-to-learn” effect, even if participants showed were not trying to learn the categories during the exposure. Additionally, this study was able to differentiate between what is learned during latent learning verses explicit teaching and provides evidence that the incidental exposure to novel objects provides an individual with latent knowledge, facilitating quicker learning later. These findings offer new insight into how a person’s everyday experiences may contribute to developing category knowledge.

Unger L, Sloutsky VM. Ready to Learn: Incidental Exposure Fosters Category Learning. Psychol Sci. 2022 May 26:9567976211061470. doi: 10.1177/09567976211061470. Epub ahead of print. PMID: 35617541.

Adult health and well-being is negatively influenced by income disparities experienced in childhood

The United States has been experiencing declining life expectancy and growing income inequality across the nation. Morbidity and mortality rates of Baby Boomers (1946-1955) have been increasing faster than expected; additionally younger cohorts are experiencing a rise in shortened life expectancies, creating a population health crisis. Research, supported by the NICHD, NIA and the CDC, sought to understand the relationship between the increases in morbidity and mortality rates of American birth cohorts from 1925-1999 and income inequality exposure in childhood. Previous research on the effects of income equality on morbidity and mortality have yielded mixed results, which are likely due to differences in countries, time periods, units of analysis, timing of effects, and other factors. Timing of effects concerns the lags between income inequality and health outcomes and has led to research that put forth the fetal origins theory, which posits that adult health, disease, morbidity, and mortality begin in part from environmental exposures in early life. The researchers in this study further build on this theory and prior research by using a cohort perspective to investigate whether income inequality experienced during childhood may have long-lasting consequences for adult health.

To investigate the correlation between declining adult health and childhood income inequality, two health outcomes: biomarkers of physiological dysregulation, and a chronic disease index, and two nationally representative datasets were used: National Health and Nutrition Examination Surveys (NHANES) 1988–2018 and Panel Studies of Income Dynamics (PSID) 1968–2013. Childhood income inequality was measured by the average Gini Index at the national level each cohort is exposed to between birth and age 18 and was computed using Internal Revenue Service pre-tax income data. The NHANES data sample was constrained to a sample size of 35,309 individuals and was broken down by race and gender to examine whether there is a lagged impact of childhood income inequality on health for all demographic groups. The PSID dataset tracks individuals over time and produces a life course history for each cohort. This sample was restricted to heads of households and spouses born 1925-1995 which resulted in 12,924 individuals and 68,271 observations (e.g., early life and adulthood socioeconomic and demographic factors). PSID data was used to supplement the analysis since NHANES data does not include measures of childhood health and family background. By linking NHANES and PSID data based on birth cohort to the Gini Index, researchers found that a child’s early exposure to income inequality is notably associated with the risk of physiological dysregulation in adulthood for all gender and racial groups, but most especially for White males and Black females.

In summary, this study confirms previous research that Americans’ health has been on the decline since the Early Baby Boomer cohort, regardless of how it is measured (biomarkers of physiological dysregulation, and a chronic disease index). This phenomenon was observed in two large nationally representative data sets and mirrors the cohort trend of increasing early life income inequality exposure. Importantly, the researchers found that early life income inequality exposure explained over 70% of cohort variation in physiological dysregulation and chronic disease index. Reducing income inequality has the potential to reverse this adverse trend and improve the health of current and future citizens.

Zheng H, Choi Y, Dirlam J, George L. Rising childhood income inequality and declining Americans' health. Soc Sci Med. 2022 Jun;303:115016. doi: 10.1016/j.socscimed.2022.115016. Epub 2022 May 7. PMID: 3556790