Body Politics
Energy expenditure and obesity across the economic spectrum
Amanda McGrosky et al.
Proceedings of the National Academy of Sciences, 22 July 2025
Abstract:
Global economic development has been associated with an increased prevalence of obesity and related health problems. Increased caloric intake and reduced energy expenditure are both cited as development-related contributors to the obesity crisis, but their relative importance remains unresolved. Here, we examine energy expenditure and two measures of obesity (body fat percentage and body mass index, BMI) for 4,213 adults from 34 populations across six continents and a wide range of lifestyles and economies, including hunter-gatherer, pastoralist, farming, and industrialized populations. Economic development was positively associated with greater body mass, BMI, and body fat, but also with greater total, basal, and activity energy expenditure. Body size-adjusted total and basal energy expenditures both decreased approximately 6 to 11% with increasing economic development, but were highly variable among populations and did not correspond closely with lifestyle. Body size-adjusted total energy expenditure was negatively, but weakly, associated with measures of obesity, accounting for roughly one-tenth of the elevated body fat percentage and BMI associated with economic development. In contrast, estimated energy intake was greater in economically developed populations, and in populations with available data (n = 25), the percentage of ultraprocessed food in the diet was associated with body fat percentage, suggesting that dietary intake plays a far greater role than reduced energy expenditure in obesity related to economic development.
Life and Death at the Margins of Society: The Mortality of the U.S. Homeless Population
Bruce Meyer, Angela Wyse & Ilina Logani
Review of Economics and Statistics, forthcoming
Abstract:
We provide the first national analysis of mortality in the U.S. homeless population by linking 140,000 homeless individuals from the 2010 Census to twelve years of all-cause mortality data from the Social Security Administration (SSA). Non-elderly homeless individuals face 3.5 times the mortality risk of the housed after accounting for demographic differences and geography, with a time pattern suggesting that persistently poor health, rather than homelessness itself, primarily drives this disparity. Employment, higher income, and more extensive recent family connections are associated with lower mortality, underscoring the persistence of health disparities into the extreme lower tail of socioeconomic disadvantage.
Income Elasticity of Demand for Healthy and Unhealthy Foods: Evidence from Lump-Sum Earned Income Tax Credit Payments
Emma LaGuardia, Leslie McGranahan & Diane Whitmore Schanzenbach
NBER Working Paper, July 2025
Abstract:
The Earned Income Tax Credit is unique among social programs in that benefits are not paid out evenly across the calendar year but are received in a lump-sum cash payment. We exploit this feature of the EITC to investigate how receiving this influx of cash affects food expenditure patterns of eligible households. We find consistent evidence that households increase their spending on healthy foods such as fresh fruit and vegetables, meat and poultry, and dairy products when they receive their tax credit. Causal estimates of the spending response to this lump-sum payment are about twice as large as the cross-section variation in spending by income implies. By contrast, there is no measurable increase in spending on soft drinks including sodas and sports drinks, and evidence suggests that spending on soft drinks is relatively inelastic with regard to income.
Short bouts, big impact: The cognitive benefits of brief exercise
Matthew Collins, Wilford Miranda & Leanne Boucher
Sport, Exercise, and Performance Psychology, forthcoming
Abstract:
Acute bouts of exercise have been shown to have measurable positive impacts on cognition. Here participants either watched a movie (control), walked (moderate exercise), or ran (vigorous exercise) on a treadmill for 30 min while their heart rate was measured before completing a paired associative learning task in which they learned 40 word pairs over the course of 10 trials. We defined learning rate as how fast the participants correctly learned the word pairs. Two days later, all participants were given a surprise recall task, and we defined long-term memory as the number of word pairs correctly recalled. We also measured working memory capacity, anxiety, and sleep quality. We found that while there was no difference between exercise conditions in the rate of learning, participants in the vigorous condition recalled more word pairs 2 days later. Analyses revealed that average heart rate and condition were the only significant predictors of long-term recall. Potential mechanisms to explain the benefits of the vigorous exercise condition on long-term retention, but not on short-term retention, are discussed.
Water Intake, Hydration, and Weight Management: The Glass is Half-Full!
Brenda Davy et al.
Physiology & Behavior, August 2025
Abstract:
The lack of practical and effective strategies to manage hunger and adhere to a weight management intervention represents a critical barrier to the weight management field. In proof-of-concept studies, we demonstrated that premeal water consumption (500 ml) acutely reduced perceived hunger and meal energy intake among middle-aged and older adults, and that premeal water consumption (500 ml, 3 times per day) increased the amount of weight lost after 12 weeks among middle-aged and older adults with overweight or obesity. However, water consumption may be important for weight management regardless of when it is consumed. This presentation summary addresses what is currently known about water intake, hydration status, and weight control. Findings from three recent systematic reviews focused on water intake and weight control are described. Potential mechanisms by which water consumption could impact appetite and hypocaloric diet adherence are discussed, and ongoing research on this topic is described.
From syringes to dishes: Improving food sufficiency through vaccination
Erkmen Aslim et al.
Journal of Public Economics, July 2025
Abstract:
This paper examines the impact of COVID-19 vaccination on food insufficiency in the United States, using data from the Household Pulse Survey. Our primary research design exploits variation in vaccine eligibility across states over time as an instrumental variable to address the endogeneity of vaccination decision. We find that vaccination had a substantial impact on food hardship by reducing the likelihood of food insufficiency by 24%, with even stronger effects among minority and financially disadvantaged populations. These results are robust to alternative specifications and the use of regression discontinuity as an alternative identification strategy. We also show that vaccine eligibility had a positive spillover impact on food assistance programs, notably reducing participation in the Supplemental Nutrition Assistance Program and the use of its benefits, suggesting that vaccination policies can help alleviate the government's fiscal burden during public health crises. Our analysis offers detailed insights into the potential mechanisms linking vaccination to food insufficiency. We demonstrate that vaccination yields changes in both material circumstances and financial expectations. Specifically, vaccination increases the use of regular income for spending needs and reduces reports of insufficient food due to unaffordability. Additionally, we find that vaccination improves financial optimism, reflected in expectations for future employment income loss and the ability to meet mortgage and debt obligations. Our findings are consistent with the notion that this optimism, along with labor market recovery, diminished the need for precautionary savings, reduced reliance on government assistance, and encouraged household spending on essential goods like food, ultimately lowering food insufficiency.
Psilocybin treatment extends cellular lifespan and improves survival of aged mice
Kosuke Kato et al.
npj Aging, July 2025
Abstract:
Psilocybin, the naturally occurring psychedelic compound produced by hallucinogenic mushrooms, has received attention due to considerable clinical evidence for its therapeutic potential to treat various psychiatric and neurodegenerative indications. However, the underlying molecular mechanisms remain enigmatic, and few studies have explored its systemic impacts. We provide the first experimental evidence that psilocin (the active metabolite of psilocybin) treatment extends cellular lifespan and psilocybin treatment promotes increased longevity in aged mice, suggesting that psilocybin may be a potent geroprotective agent.
Gifting Candy -- a Trick or a Treat?
Sarah See Stith, Xiaoxue Li & Tausifa Tajalli
University of New Mexico Working Paper, June 2025
Abstract:
Gifting creates static inefficiencies due to the mismatch between how the giver and recipient value gifts, but gifts of unhealthy goods generate even greater inefficiencies as they not only may not match the recipient's optimal choice, but also carry potential negative health costs, exacerbated by informational asymmetries. Despite the known negative effects of sugar consumption, e.g., dental cavities, obesity, and diabetes, candy is commonly gifted with many holidays specifically associated with candy gifting. This study capitalizes on holiday-driven exogenous variation in candy gifting and uses new survey data and NielsenIQ Consumer Panel data analyses to show that candy purchases related to holiday gifting exceed economically efficient levels, especially when giver-receiver relationships are more distant. Effects vary with education -- more educated givers purchase less candy for themselves but appear to exert greater negative externalities on the health of recipients through candy gifting than do less educated givers. Supply-side factors exacerbate apparent inefficiencies, e.g., through bulk packaging. The results call into question current social and regulatory attitudes towards candy gifting.
Humans have nasal respiratory fingerprints
Timna Soroka et al.
Current Biology, 7 July 2025, Pages 3011-3021
Abstract:
Long-term respiratory patterns are generated by remarkably complex brain networks. Because brains are unique, we hypothesized that their dependent respiratory patterns may be similarly unique. To test this hypothesis, we developed a wearable device that precisely measures and logs nasal airflow in each nostril separately for up to 24-h periods. We found that we could identify members of a 97-participant cohort at a remarkable 96.8% accuracy from nasal airflow patterns alone. In other words, humans have individual nasal airflow fingerprints. Moreover, in test-retest experiments, we found that these individual fingerprints remain stable over extended periods of time, such that individual identification by nasal airflow fingerprints was on par with or better than voice recognition. Finally, we find that the high sensitivity of these fingerprints provides significant indications on both physiological states, such as levels of arousal and body-mass index, and cognitive traits, such as levels of anxiety, levels of depression, and behavioral tendencies. We conclude that long-term patterns of nasal airflow reflect the brain drivers of respiration, are individually unique, and have significant implications for health, emotion, and cognition.