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The true causes of the obesity epidemic are not well understood and there are few longitudinal population-based data published examining this issue. The objective of this analysis was to examine trends in occupational physical activity during the past 5 decades and explore how these trends relate to concurrent changes in body weight in the U.S. Analysis of energy expenditure for occupations in U.S. private industry since 1960 using data from the U.S. Bureau of Labor Statistics. Mean body weight was derived from the U.S. National Health and Nutrition Examination Surveys (NHANES). In the early 1960's almost half the jobs in private industry in the U.S. required at least moderate intensity physical activity whereas now less than 20% demand this level of energy expenditure. Since 1960 the estimated mean daily energy expenditure due to work related physical activity has dropped by more than 100 calories in both women and men. Energy balance model predicted weights based on change in occupation-related daily energy expenditure since 1960 for each NHANES examination period closely matched the actual change in weight for 40-50 year old men and women. For example from 1960-62 to 2003-06 we estimated that the occupation-related daily energy expenditure decreased by 142 calories in men. Given a baseline weight of 76.9 kg in 1960-02, we estimated that a 142 calories reduction would result in an increase in mean weight to 89.7 kg, which closely matched the mean NHANES weight of 91.8 kg in 2003-06. The results were similar for women. Over the last 50 years in the U.S. we estimate that daily occupation-related energy expenditure has decreased by more than 100 calories, and this reduction in energy expenditure accounts for a significant portion of the increase in mean U.S. body weights for women and men.

Background: Metabolic and behavioral adaptations to caloric restriction (CR) in free-living conditions have not yet been objectively measured. Methodology and Principal Findings: Forty-eight (36.8+/-1.0 y), overweight (BMI 27.8+/-0.7 kg/m2) participants were randomized to four groups for 6-months; Control: energy intake at 100% of energy requirements; CR: 25% calorie restriction; CR+EX: 12.5% CR plus 12.5% increase in energy expenditure by structured exercise; LCD: low calorie diet (890 kcal/d) until 15% weight reduction followed by weight maintenance. Body composition (DXA) and total daily energy expenditure (TDEE) over 14-days by doubly labeled water (DLW) and activity related energy activity (AREE) were measured after 3 (M3) and 6 (M6) months of intervention. Weight changes at M6 were −1.0+/-1.1% (Control), −10.4+/-0.9% (CR), −10.0+/-0.8% (CR+EX) and −13.9+/-0.8% (LCD). At M3, absolute TDEE was significantly reduced in CR (−454+/-76 kcal/d) and LCD (−633+/-66 kcal/d) but not in CR+EX or controls. At M6 the reduction in TDEE remained lower than baseline in CR (−316+/-118 kcal/d) and LCD (−389+/-124 kcal/d) but reached significance only when CR and LCD were combined (−351+/-83 kcal/d). In response to caloric restriction (CR/LCD combined), TDEE adjusted for body composition, was significantly lower by −431+/-51 and −240+/-83 kcal/d at M3 and M6, respectively, indicating a metabolic adaptation. Likewise, physical activity (TDEE adjusted for sleeping metabolic rate) was significantly reduced from baseline at both time points. For control and CR+EX, adjusted TDEE (body composition or sleeping metabolic rate) was not changed at either M3 or M6. Conclusions: For the first time we show that in free-living conditions, CR results in a metabolic adaptation and a behavioral adaptation with decreased physical activity levels. These data also suggest potential mechanisms by which CR causes large inter-individual variability in the rates of weight loss and how exercise may influence weight loss and weight loss maintenance. Trial Registration: ClinicalTrials.gov NCT00099151.

Many campaigns promote the preservation and consumption of leftover food items as a critical household strategy to accomplish national consumer food waste reduction goals. We fill a gap in knowledge about the consumption and creation of leftovers in the United States by analyzing data from a pilot study in which 18 subjects tracked food selection, intake, and plate waste across all eating occasions for about one week. Subjects noted which items selected for consumption were leftovers, i.e., previously prepared but uneaten items that were stored for future consumption, and which unfinished items were saved to become leftovers. We found that 12% of items selected for consumption were leftovers while 24% of selected items that were not fully consumed were kept to become a leftover. Leftovers were most frequently vegetables, cheeses, and meats, and most frequently selected on Mondays and for lunch. Regression analyses isolate significant dining patterns with respect to leftovers, including evidence that leftovers were less likely to be fully consumed than non-leftover items, and that larger meals led to more uneaten food. This suggests that strategies to reduce meal size may be most effective in reducing food waste by limiting the creation of leftovers in the first place. Strategies to make leftovers more attractive and appealing may also reduce food waste.

While considerable knowledge has been gained through the use of established cognitive and motor assessment tools, there is a considerable interest and need for the development of a battery of reliable and validated assessment tools that provide real-time and remote analysis of cognitive and motor function in the elderly. Smartphones appear to be an obvious choice for the development of these \"next-generation\" assessment tools for geriatric research, although to date no studies have reported on the use of smartphone-based applications for the study of cognition in the elderly. The primary focus of the current study was to assess the feasibility, reliability, and validity of a smartphone-based application for the assessment of cognitive function in the elderly. A total of 57 non-demented elderly individuals were administered a newly developed smartphone application-based Color-Shape Test (CST) in order to determine its utility in measuring cognitive processing speed in the elderly. Validity of this novel cognitive task was assessed by correlating performance on the CST with scores on widely accepted assessments of cognitive function. Scores on the CST were significantly correlated with global cognition (Mini-Mental State Exam: r = 0.515, p<0.0001) and multiple measures of processing speed and attention (Digit Span: r = 0.427, p<0.0001; Trail Making Test: r = -0.651, p<0.00001; Digit Symbol Test: r = 0.508, p<0.0001). The CST was not correlated with naming and verbal fluency tasks (Boston Naming Test, Vegetable/Animal Naming) or memory tasks (Logical Memory Test). Test re-test reliability was observed to be significant (r = 0.726; p = 0.02). Together, these data are the first to demonstrate the feasibility, reliability, and validity of using a smartphone-based application for the purpose of assessing cognitive function in the elderly. The importance of these findings for the establishment of smartphone-based assessment batteries of cognitive and motor function in the elderly is discussed.

We analyze food-item level data collected from 50 adults from the United States using the Remote Food Photography Method® to provide the first estimates of plate waste gathered from adults across multiple consecutive meals and days in free-living conditions, and during laboratory-based meals with fixed food items and quantities. We find average plate waste in free-living conditions is 5.6 grams (7.7 kcals) per item and that 3.3% of all food selected is returned as plate waste, where the percent waste figure is substantially lower than previously published plate waste estimates gathered primarily from dine-out settings in the United States such as buffets and institutional settings with limited-choice meals (e.g., school cafeterias). Plate waste from the same participants during the laboratory-based meals is significantly higher with an average of 203.2 grams of solid plate waste per meal (531.3 kcals) or 39.1% of the food provided, which is similar to the plate waste percentages found reported in some school cafeteria settings. The amount of plate waste generated in free-living conditions is significantly positively associated with portion size selected for an item. In a multivariate analysis that controls for macronutrient profile, items selected from the vegetables, fats/oils/dressings, and grains categories are associated with significantly greater amounts of plate waste per item. We find no significant associations between free-living plate waste and gender, age, race or body mass index but find that women leave more plate waste in the lab meal where portion sizes are pre-determined by the researcher and similar for all respondents. We discuss possible implications of these findings for programs focused on reducing plate waste and food waste among consumers.

Caloric restriction (CR) can enhance human health, though underlying mechanisms, particularly related to energy expenditure, remain unclear. This ancillary investigation of the only randomized controlled trial of long-term CR in normal-weight adults, aimed to quantify metabolic adaptation following weight loss by assessing changes in energy-expending tissues and organs using magnetic resonance imaging (MRI). Participants in the CR group were prescribed 24-month 25% CR causing a ~ 13% weight loss at 12 months followed by 12 month weight maintenance, whereas the control group maintained ad libitum food intake throughout. The CR group experienced reductions in adipose tissue and skeletal muscle mass compared to the control group. Sleeping energy expenditure decreased more than predicted at 12 months, regardless of whether predictions were based on body mass, dual x-ray absorptiometry (DXA)-derived body composition, or MRI-derived tissue mass. MRI-derived models explained slightly more variation in energy expenditure at baseline and detected greater metabolic adaptation than simpler models based on body mass only. At 24 months, only the models based on DXA and MRI were indicative of persistent metabolic adaptation. These findings highlight the complexity of metabolic responses to CR. Further, advanced imaging techniques hold potential to provide insight into organ-specific contributions to energy metabolism during CR.

Background/objectivesThe Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy Phase 2 (CALERIE) study showed that individuals who are nonobese were able to undergo significant calorie restriction (CR), yet the time course changes in adherence, weight, and appetite are unknown. This analysis aimed to investigate the time course changes in adherence, body weight, and appetite during the CALERIE study.Subjects/methodsOverall, 143 participants (body mass index: 21.9–28.0 kg/m2) were randomized to a CR group that aimed to achieve 25% CR for 2 years. Throughout the intervention, body weight was measured, and appetite was assessed through visual analogue scales. Algorithms were utilized with body weight measurements to calculate adherence percentile score. Participants targeted an adherence percentile score of 50, though being between 80 (lowest acceptable adherence) and 10 (highest acceptable adherence) was adequate. Polynomial regression analyses were used to assess time course changes.ResultsPolynomials indicated that adherence percentile score increased above 50 after approximately week 20, although adherence remained acceptable (adherence percentile score less than 80) (R2 = 0.89; P < 0.001). Weight loss occurred until approximately week 60 and then plateaued (R2 ≥ 0.92; P < 0.001). Hunger and thirst increased (R2 ≥ 0.30; P < 0.001), but the total increase in scale scores were <10 mm throughout the intervention.ConclusionsIn individuals who are nonobese, adherence to 25% CR declines after 20 weeks, but 2 years of CR that stimulates a meaningful reduction in weight, promotes aging-related benefits and negligibly affects appetite is viable.

Weight loss (WL) differences between isocaloric high-carbohydrate and high-fat diets are generally small; however, individual WL varies within diet groups. Genotype patterns may modify diet effects, with carbohydrate-responsive genotypes losing more weight on high-carbohydrate diets (and vice versa for fat-responsive genotypes). We investigated whether 12-week WL (kg, primary outcome) differs between genotype-concordant and genotype-discordant diets. In this 12-week single-center WL trial, 145 participants with overweight/obesity were identified a priori as fat-responders or carbohydrate-responders based on their combined genotypes at ten genetic variants and randomized to a high-fat (n = 73) or high-carbohydrate diet (n = 72), yielding 4 groups: (1) fat-responders receiving high-fat diet, (2) fat-responders receiving high-carbohydrate diet, (3) carbohydrate-responders receiving high-fat diet, (4) carbohydrate-responders receiving high-carbohydrate diet. Dietitians delivered the WL intervention via 12 weekly diet-specific small group sessions. Outcome assessors were blind to diet assignment and genotype patterns. We included 122 participants (54.4 [SD:13.2] years, BMI 34.9 [SD:5.1] kg/m 2 , 84% women) in the analyses. Twelve-week WL did not differ between the genotype-concordant (−5.3 kg [SD:1.0]) and genotype-discordant diets (−4.8 kg [SD:1.1]; adjusted difference: −0.6 kg [95% CI: −2.1,0.9], p  = 0.50). With the current ability to genotype participants as fat- or carbohydrate-responders, evidence does not support greater WL on genotype-concordant diets. ClinicalTrials identifier: NCT04145466. Genotype patterns may modify diet effects on weight loss, with greater weight loss on genotype-concordant diets. Here, the authors show that with the current ability to genotype participants as fat- or carbohydrate-responders, evidence does not support greater weight loss on genotype-concordant diets.

Despite well-documented health benefits from exercise, a study on national trends in achieving the recommended minutes of physical activity guidelines has not improved since the guidelines were published in 2008. Peer interactions have been identified as a critical factor for increasing a population’s physical activity. The objective of this study is for establishing criteria for social influences on physical activity for establishing criteria that lead to exercise persistence. A system of differential equations was developed that projects exercise trends over time. The system includes both social and non-social influences that impact changes in physical activity habits and establishes quantitative conditions that delineate population-wide persistence habits from domination of sedentary behavior. The model was generally designed with parameter values that can be estimated to data. Complete absence of social or peer influences resulted in long-term dominance of sedentary behavior and a decline of physically active populations. Social interactions between sedentary and moderately active populations were the most important social parameter that influenced low active populations to become and remain physically active. On the other hand, social interactions encouraging moderately active individuals to become sedentary drove exercise persistence to extinction. Communities should focus on increasing social interactions between sedentary and moderately active individuals to draw sedentary populations to become more active. Additionally, reducing opportunities for moderately active individuals to engage with sedentary individuals through sedentary social activities should be addressed.

Background It is unclear how physical activity energy expenditure (PAEE) influences calorie restriction (CR)-induced benefits in individuals without obesity. We examined associations between PAEE and healthspan markers and physical activity (PA) time during prolonged CR. Methods In Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE)™ 2, participants without obesity were randomized to 25% CR or ad libitum control. This post-hoc analysis included baseline and 24-month data from participants in both groups who demonstrated CR. PAEE was calculated from total and resting energy expenditure, measured using doubly labelled water and indirect calorimetry, respectively, and adjusted for covariates to obtain a residual value that was used as the primary exposure variable. Outcomes included grip strength, aerobic capacity, glucose, insulin, blood lipids, and self-reported PA time. Results Overall, 136 participants (97 [71.3%] females; age: 38.6 [7.4] years; BMI: 25.3 [1.7] kg/m²) who showed CR were analyzed. A smaller decrease in PAEE was associated with improved grip strength (estimate = 0.504 [95% CI: 0.023, 0.986] kg), homeostatic model assessment of insulin resistance (estimate: -0.032 [95% CI: -0.062, -0.002]), and high-density lipoprotein-cholesterol (1.011 [95% CI: 0.356, 1.666] mg/dL; P  ≤ 0.040). PAEE change was not associated with aerobic capacity, low-density lipoprotein-cholesterol, triglycerides, glucose, or insulin ( P  ≥ 0.053). A smaller PAEE decline was associated with more PA minutes ( P  = 0.028). For some blood lipids, change in PAEE interacted with baseline BMI class ( P  ≤ 0.029): in participants who were overweight, higher PAEE was associated with lower triglyceride and triglyceride: high-density lipoprotein-cholesterol ratio ( P  ≤ 0.022), whereas in participants who were normal weight, it was related to increased total-cholesterol ( P  = 0.006). Conclusion A smaller reduction in PAEE during CR was associated with small improvements in several healthspan markers and greater PA time. Maintaining PAEE during CR may enhance healthspan in individuals without obesity. Trial registration clinicaltrials.gov registration (NCT00427193).