Fueling the Obesity Epidemic? Artificially Sweetened Beverage Use and Long‐term Weight Gain

We have examined the relationship between artificially sweetened beverage (ASB) consumption and long-term weight gain in the San Antonio Heart Study. From 1979 to 1988, height, weight, and ASB consumption were measured among 5,158 adult residents of San Antonio, Texas. Seven to eight years later, 3,682 participants (74% of survivors) were re-examined. Outcome measures were incidence of overweight/obesity (OW/OB(inc)) and obesity (OB(inc)) (BMI > or = 25 and > or = 30 kg/m(2), respectively), and BMI change by follow-up (DeltaBMI, kg/m(2)). A significant positive dose-response relationship emerged between baseline ASB consumption and all outcome measures, adjusted for baseline BMI and demographic/behavioral characteristics. Consuming >21 ASBs/week (vs. none) was associated with almost-doubled risk of OW/OB (odds ratio (OR) = 1.93, P = 0.007) among 1,250 baseline normal-weight (NW) individuals, and doubled risk of obesity (OR = 2.03, P = 0.0005) among 2,571 individuals with baseline BMIs <30 kg/m(2). Compared with nonusers (+1.01 kg/m(2)), DeltaBMIs were significantly higher for ASB quartiles 2-4: +1.46 (P = 0.003), +1.50 (P = 0.002), and +1.78 kg/m(2) (P < 0.0001), respectively. Overall, adjusted DeltaBMIs were 47% greater among artificial sweetener (AS) users than nonusers (+1.48 kg/m(2) vs. +1.01 kg/m(2), respectively, P < 0.0001). In separate analyses--stratified by gender; ethnicity; baseline weight category, dieting, or diabetes status; or exercise-change category--DeltaBMIs were consistently greater among AS users. These differences, though not significant among exercise increasers, or those with baseline diabetes or BMI >30 kg/m(2) (P = 0.069), were significant in all 13 remaining strata. These findings raise the question whether AS use might be fueling--rather than fighting--our escalating obesity epidemic.     

Does Dieting Lead to Weight Gain? A Four‐Year Longitudinal Study of Middle School Girls

Objective: A majority of the published longitudinal research on children has reported that dieting is related to weight gain at a later point in time. The purpose of this study was to look at weight control behaviors and patterns of weight gain and loss, specifically whether dieting is related to weight gain. Research Methods and Procedures: Baseline data were collected from 1358 female students in grades 6 to 9 from schools in Hayward, CA, and Tucson, AZ. Data were obtained annually over a 4‐year period. Paper‐and‐pencil questionnaires and height and weight were obtained during the students’ regular classroom periods. Dieting was measured both with the single item, “In the past year, how often have you been on a diet to lose weight?” scored from “never” to “always,” and with a Dieting Behavior Scale including five items on weight control behaviors. Changes in BMI z‐scores were analyzed. Results: On average, girls who reported “never” dieting were most likely to have an increased BMI z‐score at the next measurement, and those who reported “always” dieting were most likely to have a decreased BMI z‐score. The same pattern was true for the Dieting Behavior Scale. Discussion: Our finding that dieting and weight gain were not related, independently of initial BMI, does not mean that dieting to lose weight is appropriate, especially among young girls. Additional research is needed both to examine this relationship and to determine exactly what behaviors children are engaging in when they report that they are dieting.     

Does Exposure to Trichloroethene in Low Doses Constitute a Cancer Risk to Humans?

Although chronic exposure to high doses of trichloroethene causes tumors of the lung, liver, and kidney in experimental animals, the epidemiology data in humans exposed to trichloroethene as a whole fail to support a causal association between trichloroethene exposure and cancers of the lungs, liver, or kidneys in humans at environmentally relevant concentrations. Environmentally relevant concentrations of trichloroethene are defined as 50 ppb (50 µg/L) in water or 5 ppb (27 µg/m³) in air. Tumor induction by trichloroethene in rodents exposed to very high doses over their whole lifespan has been observed in the kidney of rats and in the lung and liver of mice. Mechanistic data demonstrate that species-specific processes are involved in the carcinogenicity associated with chronic trichloroethene exposure in rodents. Based on these data and the results of recent well-conducted epidemiology studies, it can be concluded that humans exposed to trichloroethene at environmentally relevant concentrations are not at an increased risk for developing cancer.     

Does a High‐protein Diet Improve Weight Loss in Overweight and Obese Children?

Objective: To evaluate the effect of a high‐protein diet on anthropometry, body composition, subjective appetite, and mood sensations in overweight and obese children attending a residential weight‐loss camp. Research Methods and Procedures: Children (120; BMI, 33.1 ± 5.5 kg/m²; age, 14.2 ± 1.9 years) were randomly assigned to either a standard or high‐protein diet group (15% vs. 22.5% protein, respectively). All children were assessed at baseline and at the end of the camp for anthropometry, body composition, blood pressure, biochemical variables (n = 27), and subjective appetite and mood sensations (n = 50). Results: Attendance at the weight‐loss camp resulted in significant improvements in most measures. Campers lost 5.5 ± 2.9 kg in body weight (p < 0.001) and 3.8 ± 5.4 kg in fat mass (p < 0.001) and reduced their BMI standard deviation score by 0.27 ± 0.1 (p < 0.001) and their waist circumference by 6.6 ± 2.8 cm (p < 0.001). Subjective sensations of hunger increased significantly over the camp duration, but no other changes in appetite or mood were observed. There were no significant differences between the two diets on any physical or subjective measures. Discussion: Weight‐loss camps are effective in assisting children to lose weight and improve on a range of health outcomes, independently of the protein content of the diet. The implications of an increase in hunger associated with weight loss needs to be considered. Further work is warranted to investigate whether higher levels of dietary protein are feasible or effective in longer‐term weight‐loss interventions of this type.     

Long‐term dietary shift and population decline of a pelagic seabird—A health check on the tropical Atlantic?

In the face of accelerating ecological change to the world's oceans, seabirds are some of the best bio‐indicators of marine ecosystem function. However, unravelling ecological changes that pre‐date modern monitoring programmes remains challenging. Using stable isotope analysis of feathers and regurgitants collected from sooty terns (Onychoprion fuscatus) nesting at a major Atlantic colony, we reconstructed a long‐term dietary time series from 1890 to the present day and show that a significant dietary shift occurred during the second half of the twentieth century coinciding with an apparent population collapse of approximately 84%. After correcting for the “Suess Effect,” δ¹³C in feathers declined by ~1.5‰ and δ¹⁵N by ~2‰ between the 1890s and the present day, indicating that birds changed their diets markedly over the period of population decline. Isotopic niches were equally wide before and after the population collapse but isotopic mixing models suggest that birds have grown ever more reliant on nutrient‐poor squid and invertebrates as teleost fish have declined in availability. Given that sooty terns rely heavily on associations with sub‐surface predators such as tuna to catch fish prey, the rapid expansion of industrialized fisheries for these species over the same period seems a plausible mechanism. Our results suggest that changes to marine ecosystems over the past 60 years have had a dramatic impact on the ecology of the most abundant seabird of tropical oceans, and highlight the potentially pervasive consequences of large predatory fish depletion on marine ecosystem function.     

Does a long‐term shift in Wood Stork diet foreshadow adaptability to human‐induced rapid environmental change?

To preserve biodiversity, identifying at‐risk populations and developing conservation plans to mitigate the effects of human‐induced rapid environmental change (HIREC) are essential. Changes in diet, especially for food‐limited species, can aid in detecting populations being impacted by HIREC, and characterizing the quality, abundance, and temporal and spatial consistency of newly consumed food items may provide insight concerning the likelihood of a species persisting in a changing environment. We used Wood Storks (Mycteria americana) nesting in the Florida Everglades as a model system to study the possible effects of HIREC on a food‐limited population. We compared the diets of Wood Storks in 2013 and 2014 with those reported during the 1970s before major anthropogenic activities affected the Everglades system and prey availability. Wood Storks in our study consumed more large‐bodied sunfish species (Lepomis spp.), fewer native marsh fishes, and more non‐native fish species than during the 1970s. Large sunfish and non‐native fish are relatively rare in the drying pools of Everglades marshes where storks traditionally forage, suggesting that Wood Storks may be using novel foraging habitats such as created wetlands (i.e., canals and stormwater ponds). Although created wetlands have long hydroperiods conducive to maintaining large‐bodied fishes and could provide alternative foraging habitat when prey availability is reduced in natural marshes, additional studies are needed to determine the extent to which these wetlands are used by Wood Storks and, importantly, the quality of prey items potentially available to foraging Wood Storks in created wetlands.     

Does forest extent affect salamander survival? Evidence from a long‐term demographic study of a tropical newt

Forest loss has been associated with reduced survival in many vertebrates, and previous research on amphibians has mostly focused on effects at early life stages. Paramesotriton hongkongensis is a tropical newt that breeds in streams but spends up to 10 months per year in terrestrial habitats. Populations are threatened by habitat degradation and collection for the pet trade, but the cryptic terrestrial lifestyle of this newt has limited our understanding of its population ecology, which inhibits development of a species‐specific conservation plan. We conducted an eight‐year (2007–2014) mark–recapture study on four P. hongkongensis populations in Hong Kong and used these data to evaluate relationships between forest cover, body size, and rainfall on survival and to estimate population sizes. Hong Kong has been subjected to repeated historic territory‐wide deforestation, and thus, we wanted to determine whether there was a link between forest extent as a proxy of habitat quality and newt demography. Annual survival was positively associated with forest cover within core habitat of all populations and negatively related to body size. Mean annual survival (~60%) was similar to that of other stream‐dwelling amphibians, but varied among years and declined substantially in 2012–2013, perhaps due to illegal collection. Despite the link between forest extent and survival, population sizes declined at the most forested site by 40% and increased by 104% and 134% at two others. Forest protection and consequential secondary succession during recent decades in Hong Kong may have been responsible for persistence of P. hongkongensis populations.     

Long‐lived dwarf mice: are bile acids a longevity signal?

Pathways that control aging act via regulated biochemical processes, among which metabolism of xenobiotics (potentially harmful chemical agents encountered as environmental toxicants, for example, drugs, or produced internally) is one possible candidate. A new study of long-lived Ghrhr mutant mice reports that increased bile acid levels activate xenobiotic metabolism via the nuclear receptor, farnesoid X receptor. This increases resistance to xenobiotic stress, possibly contributing to longevity.     

Long‐term dynamics of bird diversity in forest and suburb: decay,turnover or homogenization?

Aim Urbanization and deforestation are important drivers of biodiversity change. However, long‐term changes in faunal communities within urbanizing regions are poorly understood. We investigated how well observed community changes in both space and time agree with expectations based on current paradigms in urban ecology. Location Greater Brisbane region, Australia. Methods We compared bird assemblages in two time‐periods 15 years apart, at multiple sites in remnant forest and residential suburbs across an urbanizing landscape. Differences in assemblage composition, species abundances and functional groupings were assessed within and between habitats. Results Compared with forest, suburbs in both time‐periods had over twice the total bird abundance, a different species composition, greater between‐site community similarity, a greater proportion of non‐native species and greater dominance by large‐bodied species. These differences corresponded with changes in sites whose habitat was converted from forest to suburb. Between time‐periods, abundances of 58% of suburban species changed significantly compared with those of 11% in forest. Increaser species outnumbered decreasers in suburbs, with the reverse in forest. Abundance of small‐bodied birds decreased 70% in suburbs and 20% in forest. Broad‐spectrum competitors and nest predators were common among suburban increasers. Among invasive species, the number of increasers was counterbalanced by decreasers. Both site‐scale species richness and between‐site community similarity increased to a small extent in both habitats. Main conclusions Species composition and ecological function of suburban bird communities were very dynamic. Suburban assemblages were neither a subset of forest species nor an increasingly non‐native compilation. Communities in large forest patches were comparatively stable. The notion of habitat‐specific species turnover better characterizes the nature of most changes than either species decline or homogenization, even though both of these were evident. There is considerable scope for careful urban planning, focused on both among‐ and within‐habitat variety, to sustain bird diversity in urbanizing landscapes.     

Does anti‐parasitoid defense explain host‐plant selection by a polyphagous caterpillar?

While studies of tri-trophic interactions have uncovered a variety of mechanisms influencing the dietary specialization of insect herbivores, such studies have neglected host-plant selection by generalists. Here, we report an initial investigation on how host-plant quality and a tachinid parasitoid interact to affect the survival and host-plant selection by a polyphagous herbivore. This herbivore, Grammia geneura (Strecker) (Lepidoptera: Arctiidae), is a food-mixing caterpillar that feeds preferentially on forbs. A previous study suggested that G. geneura might eat certain host species for reasons other than benefits of physiological utilization. We hypothesized that host-plant mediated defenses could act against parasitoids, the major mortality agents of late instar G. geneura . Field observations indicated that caterpillars sometimes survived an attack by the parasitoid Exorista mella Walker (Diptera: Tachinidae) in nature. Laboratory experiments showed that the survival of parasitized caterpillars increased on acceptable but nutritionally inferior host-plant species, indicating that anti-parasitoid defense may explain host-plant selection in this dietary generalist. We found no indication that host-plant selection changed according to the parasitism status of individual caterpillars.