OBJECTIVEWe sought to define 24-h glycemia in normal-weight and obese pregnant women using continuous glucose monitoring (CGM) while they consumed a habitual and controlled diet both early and late in pregnancy.RESEARCH DESIGN AND METHODSGlycemia was prospectively measured in early (15.7 ± 2.0 weeks’ gestation) and late (27.7 ± 1.7 weeks’ gestation) pregnancy in normal-weight (n = 22) and obese (n = 16) pregnant women on an ad libitum and controlled diet. Fasting glucose, triglycerides (early pregnancy only), nonesterified fatty acids (FFAs), and insulin also were measured.RESULTSThe 24-h glucose area under the curve was higher in obese women than in normal-weight women both early and late in pregnancy despite controlled diets. Nearly all fasting and postprandial glycemic parameters were higher in the obese women later in pregnancy, as were fasting insulin, triglycerides, and FFAs. Infants born to obese mothers had greater adiposity. Maternal BMI (r = 0.54, P = 0.01), late average daytime glucose (r = 0.48, P < 0.05), and late fasting insulin (r = 0.49, P < 0.05) correlated with infant percentage body fat. However, early fasting triglycerides (r = 0.67, P < 0.001) and late fasting FFAs (r = 0.54, P < 0.01) were even stronger correlates.CONCLUSIONSThis is the first study to demonstrate that obese women without diabetes have higher daytime and nocturnal glucose profiles than normal-weight women despite a controlled diet both early and late in gestation. Body fat in infants, not birth weight, was related to maternal BMI, glucose, insulin, and FFAs, but triglycerides were the strongest predictor. These metabolic findings may explain higher rates of infant macrosomia in obese women, which might be targeted in trials to prevent excess fetal growth.

BackgroundWhile physical activity has been shown to improve cognitive performance and well-being, office workers are essentially sedentary. We compared the effects of physical activity performed as (i) one bout in the morning or (ii) as microbouts spread out across the day to (iii) a day spent sitting, on mood and energy levels and cognitive function.MethodsIn a randomized crossover trial, 30 sedentary adults completed each of three conditions: 6 h of uninterrupted sitting (SIT), SIT plus 30 min of moderate-intensity treadmill walking in the morning (ONE), and SIT plus six hourly 5-min microbouts of moderate-intensity treadmill walking (MICRO). Self-perceived energy, mood, and appetite were assessed with visual analog scales. Vigor and fatigue were assessed with the Profile of Mood State questionnaire. Cognitive function was measured using a flanker task and the Comprehensive Trail Making Test. Intervention effects were tested using linear mixed models.ResultsBoth ONE and MICRO increased self-perceived energy and vigor compared to SIT (p < 0.05 for all). MICRO, but not ONE, improved mood, decreased levels of fatigue and reduced food cravings at the end of the day compared to SIT (p < 0.05 for all). Cognitive function was not significantly affected by condition.ConclusionsIn addition to the beneficial impact of physical activity on levels of energy and vigor, spreading out physical activity throughout the day improved mood, decreased feelings of fatigue and affected appetite. Introducing short bouts of activity during the workday of sedentary office workers is a promising approach to improve overall well-being at work without negatively impacting cognitive performance.Trial registration NCT02717377, registered 22 March 2016.

Objective The roles that energy expenditure (EE) and nutrient oxidation play in a predisposition for weight gain in humans remains unclear. Subjects We measured EE and respiratory exchange ratio (RER) in non-obese obesity prone (OP; n=22) and obesity resistant (OR; n=30) men and women following a eucaloric diet and after 3 days of overfeeding (1.4x basal energy). Results Twenty four hour EE, adjusted for fat free mass and sex, measured while consuming a eucaloric diet was not different between OP and OR subjects (2367 ± 80 vs. 2285 ± 98 kcals; p=0.53). Following overfeeding, EE increased in both OP and OR (OP: 2506 ± 63.7, p<0.01; OR: 2386 ± 99 kcals, p<0.05). Overfeeding resulted in an increase in 24h RER (OP: 0.857 ± 0.01 to 0.893 ± 0.01, p=0.01; OR: 0.852 ± 0.01 to 0.886 ± 0.01, p=0.005), with no difference between groups in either the eucaloric or overfeeding conditions (p>0.05). Nighttime RER (~10pm-6:30am) did not change with overfeeding in OR (0.823 ± 0.02 vs. 0.837 ± 0.01, p=0.29), but increased significantly in OP subjects (0.798 ± 0.15 to 0.839 ± 0.15, p<0.05), suggesting that fat oxidation during the night was down-regulated to a greater extent in OP subjects following a brief period of overfeeding, as compared to OR subjects who appeared to maintain their usual rate of fat oxidation. Protein oxidation increased significantly in both OP (p<0.001) and OR (p<0.01) with overfeeding, with no differences between OP and OR. Conclusion These results support the idea that overfeeding a mixed diet results in increases in EE and RER, but these increases in EE and RER are likely not responsible for obesity resistance. Adaptive responses to overfeeding that occur during the night may play a role in opposing weight gain.

Despite living in an environment that promotes weight gain in many individuals, some individuals maintain a thin phenotype while self-reporting expending little or no effort to control their weight. When compared with obesity prone (OP) individuals, we wondered if obesity resistant (OR) individuals would have higher levels of spontaneous physical activity (SPA) or respond to short-term overfeeding by increasing their level of SPA in a manner that could potentially limit future weight gain. SPA was measured in 55 subjects (23 OP and 32 OR) using a novel physical activity monitoring system (PAMS) that measured body position and movement while subjects were awake for 6 days, either in a controlled eucaloric condition or during 3 days of overfeeding (1.4× basal energy) and for the subsequent 3 days (ad libitum recovery period). Pedometers were also used before and during use of the PAMS to provide an independent measure of SPA. SPA was quantified by the PAMS as fraction of recording time spent lying, sitting, or in an upright posture. Accelerometry, measured while subjects were in an upright posture, was used to categorize time spent in different levels of movement (standing, walking slowly, quickly, etc.). There were no differences in SPA between groups when examined across all study periods (P > 0.05). However, 3 days following overfeeding, OP subjects significantly decreased the amount of time they spent walking (−2.0% of time, P = 0.03), whereas OR subjects maintained their walking (+0.2%, P > 0.05). The principle findings of this study are that increased levels of SPA either during eucaloric feeding or following short term overfeeding likely do not significantly contribute to obesity resistance although a decrease in SPA following overfeeding may contribute to future weight gain in individuals prone to obesity.

OBJECTIVE: We tested the hypothesis that three days of overfeeding ( OF ) decreases dietary fat oxidation and predicts longitudinal weight change in adults classified as obesity-prone ( OP ) and obesity-resistant ( OR ) based on self-identification, personal and family weight history. Changes in diurnal profiles of plasma metabolites and hormones were measured to probe mechanisms. METHODS: Adults identified as OP (n=22; BMI: 23.9 ± 2.4 kg/m 2 ) and OR (n=30; BMI: 20.5 ± 2.2 kg/m 2 ) completed 3 days of eucaloric ( EU ) feeding and 3 days of OF. On day three, 24-hr total and dietary fat oxidation were measured using room calorimetry and an oral 14 C tracer. Plasma glucose, insulin, triglycerides ( TG ), and non-esterified fatty acid ( NEFA ) concentrations were frequently sampled over 24-hr. Body composition was measured annually for 4.0 ± 1.4 years in a sub-sample (n=19 OP and 23 OR). RESULTS: Dietary fat oxidation over 24-hr was not altered by OF versus EU (P=0.54). Weight gain in OP correlated with lower nocturnal NEFA concentrations during OF (r=−0.60, P=0.006) and impaired fuel selection over 24-hr (metabolic inflexibility, wake RQ-sleep RQ) (r=−0.48, P=0.04). CONCLUSIONS: Short-term OF did not alter dietary fat oxidation. Lower nocturnal NEFA availability and metabolic inflexibility to overfeeding may be factors contributing to weight gain.

ObjectiveTo determine whether metabolic responses to short-term overfeeding predict longitudinal changes in body weight.Methods24h energy expenditure (EE) and substrate utilization were measured at baseline in a room calorimeter following 3d of eucaloric and hypercaloric feeding (40% excess) in a sample of lean adults (n: 34; age: 28±2 years; body mass index: 22±3 kg/m2). Body mass and fat mass (DXA) were measured annually for 5yrs. Regression analyses examined whether changes in EE and fuel use with overfeeding predicted body weight and composition changes over 5yrs.ResultsOverfeeding increased EE and reduced fat oxidation when examined over the 24h, waking, and nocturnal periods. Absolute change in body mass over 5y was 3.0±0.6 kg (average rate of change = 0.7±0.1 kg per year, p<0.001). Lower nocturnal (but not 24h or waking) fat oxidation (r =−0.42, p=0.01) and EE (r=−0.33, p =0.05) with overfeeding were the strongest predictors of 5y weight gain. When adjusted for covariates, changes in nocturnal fat oxidation and EE with overfeeding predicted 41% of the variance weight change (p=0.02).ConclusionsFailure to maintain fat oxidation at night following a period of overfeeding appears to be associated with a metabolic phenotype favoring weight gain.

What is already known?Objective: Appetite responses to 3 days of overfeeding (OF) were examined as correlates of longitudinal weight change in adults classified as obesity prone (OP) or obesity resistant (OR). Methods: OP (n = 22) and OR (n = 30) adults consumed a controlled eucaloric and OF diet (140% of energy needs) for 3 days, followed by 3 days of ad libitum feeding. Hunger and satiety were evaluated by visual analog scales. Ghrelin and peptide YY (PYY) levels were measured during a 24-hour inpatient visit on day 3. Body weight and composition were measured annually for 4.0 ± 1.3 years. Results: Dietary restraint and disinhibition were greater in OP than OR (mean difference: 3.5 ± 1.2 and 3.3 ± 0.9, respectively; P < 0.01) participants, and disinhibition was associated with longitudinal weight change (n = 48; r = 0.35; P = 0.02). Compared with the eucaloric diet, energy intake fell significantly in OR participants following OF (P = 0.03) but not in OP (P = 0.33) participants. Twenty-four-hour PYY area under the curve values increased with OF in OR (P = 0.02) but not in OP (P = 0.17) participants. Furthermore, changes in PYY levels with OF correlated with measured energy intake (r = −0.36; P = 0.01). Conclusions: Baseline disinhibition and PYY responses to OF differed between OP and OR adults. Dietary disinhibition was associated with 5-year longitudinal weight gain. Differences in appetite regulation may underlie differences in propensity for weight gain.

Objective To examine the impact of a one-year pragmatic obesity trial on primary care providers’ (PCPs) perspectives of treatment. Methods PCPs from four intervention (PCP-I) and five control clinics (PCP-C) completed pre- and post-intervention surveys on weight loss counseling, comfort discussing obesity treatments and perceived effectiveness of interventions; questions were rated on 0–10 Likert scales. Only PCP-I received patient updates and education about obesity management. Results Eighty PCPs completed pre-intervention surveys [pre] (71% female, 71% physicians); 82 PCPs completed post-intervention surveys [post] (66% female, 70% physicians). PCPs were most comfortable discussing exercise (median 8, interquartile range 7–9), even after the trial (P=0.71). PCPs were least comfortable discussing phentermine/topiramate ER ( 4 , 2 – 6 ), but developed more comfort (pre 3, 1.5–6; post 5, 3–7; P<0.001). Only PCP-I became more comfortable discussing phentermine (pre 7, 4–8; post 8, 7–9; P=0.026). After the trial, PCPs rated phentermine/topiramate ER more effective (pre 5, 3–6; post 7, 5–8; P<0.001); only PCP-I rated exercise less effective (pre 7, 4–8.5; post 5, 3–7; P=0.035) and phentermine more effective (pre 5, 5–7; post 7, 6–8; P<0.001). Conclusions PCPs initially overvalued exercise and undervalued medications. PCPs exposed to education and experience gave higher comfort and effectiveness ratings to weight loss medications.