Levine, James A.

Objective Little is known about long‐term metabolic (energy expenditure) adaptation after bariatric surgery. Methods Resting metabolic rate under basal conditions (RMR), total daily energy expenditure (TDEE), and body composition were measured in 25 participants in the Longitudinal Assessment of Bariatric Surgery‐2. Results Six months after surgery, BMI (±SD) decreased (47 ± 6 kg/m 2 to 37 ± 5 kg/m 2 ), body fat went from 48% ± 6% to 40% ± 6% fat, and fat‐free mass went from 67 ± 9 kg to 60 ± 9 kg. In absolute terms, RMR and TDEE both decreased significantly (1,730 ± 278 kcal/d vs. 1,430 ± 200 kcal/d and 2,879 ± 544 kcal/d vs. 2,369 ± 304 kcal/d), and the achieved energy balance was −1,293 ± 355 kcal/d. Sixteen of these participants underwent repeated measures at ∼24 months; TDEE decreased 6 months postoperatively (2,957 ± 540 kcal/d to 2,423 ± 324 kcal/d; P = 0.0003), but at ∼24 months, TDEE (2,602 ± 471 kcal/d) was not significantly different compared with month 6. The average negative energy balance from baseline to month 24 was −379 ± 131 kcal/d. Conclusions RMR and TDEE fall precipitously in the first 6 months after bariatric surgery, but these adaptive changes were no longer significant after 2 years.

Dual-energy X-ray absorptiometry (DEXA) is reported to be inferior to computed tomography (CT) to measure changes in appendicular soft tissue composition. We compared CT- and DEXA-measured thigh muscle and fat mass to evaluate the random and systematic discrepancies between these two methods. Thigh skeletal muscle area (single-slice CT) was suboptimally ( r2= 0.74, P < 0.0001) related to DEXA-measured thigh fat-free mass (FFM). In contrast, thigh muscle and adipose tissue volumes (multislice CT) were highly related to DEXA-measured thigh FFM and fat (both r2= 0.96, P < 0.0001). DEXA-measured leg fat was significantly less than multislice-CT-measured leg adipose tissue volume, whereas multislice-CT-measured leg muscle mass was less ( P < 0.0001) than DEXA-measured leg FFM. The systematic discrepancies between the two approaches were consistent with the 10–15% nonfat components of adipose tissue. In conclusion, CT and DEXA measures of appendicular soft tissue are highly related. Systematic differences between DEXA and CT likely relate to the underlying principles of the techniques.

Nonexercise activity thermogenesis (NEAT) accounts for the vast majority of nonresting metabolic rate and changes in NEAT-predicted susceptibility to fat gain with overfeeding. Measuring physical activity and its components in free-living humans has been a long-standing challenge. In this study, we combine information about lightweight sensors that capture data on body position and motion with laboratory measures of energy expenditure to calculate nonfidgeting NEAT. This measurement of nonfidgeting NEAT was compared with total NEAT measured in a room calorimeter in 11 healthy subjects. The measurement of nonfidgeting NEAT accounted for 85 ± 9% of total NEAT measured in the room calorimeter. The intraclass correlation coefficient for the two methods was 0.86 (95% confidence interval 0.56, 0.96; P < 0.05). This suggests that 86% of the variance is attributable to between-subject variance and 14% to between-method disagreement. These instruments are applicable to free-living subjects; they are stand-alone, are lightweight, and allow normal daily activities. This novel technology has potential application for not only assessing NEAT but also tracking physical activity in free-living humans.

Triiodothyronine (T3) increases O2 and nutrient flux through mitochondria (Mito) of many tissues, but it is unclear whether ATP synthesis is increased, particularly in different types of skeletal muscle, because variable changes in uncoupling proteins (UCP) and enzymes have been reported. Thus Mito ATP production was measured in oxidative and glycolytic muscles, as well as in liver and heart, in rats administered T3 for 14 days. Relative to saline-treated controls, T3 rats had 80, 168, and 62% higher ATP production in soleus muscle, liver, and heart, respectively, as well as higher activities of citrate synthase (CS; 63, 90, 25%) and cytochrome c oxidase (COX; 119, 225, 52%) in the same tissues (all P < 0.01). In plantaris muscle of T3 rats, CS was only slightly higher (17%, P < 0.05) than in controls, and ATP production and COX were unaffected. mRNA levels of COX I and III were 33 and 47% higher in soleus of T3 rats ( P < 0.01), but there were no differences in plantaris. In contrast, UCP2 and -3 mRNAs were 2.5- to 14-fold higher, and protein levels were 3- to 10-fold higher in both plantaris and soleus of the T3 group. We conclude that T3 increases oxidative enzymes and Mito ATP production and Mito-encoded transcripts in oxidative but not glycolytic rodent tissues. Despite large increases in UCP expression, ATP production was enhanced in oxidative tissues and maintained in glycolytic muscle of hyperthyroid rats.

Purpose: To evaluate a healthy eating and physical activity intervention for immigrant families, derived through community-based participatory research. Design: The Healthy Immigrant Families study was a randomized controlled trial with delayed intervention control group, with families as the randomization unit. Setting: US Midwest city. Participants: Participants were recruited by community partners from Hispanic, Somali, and Sudanese immigrant communities. Intervention: Family health promoters from participating communities delivered 6 healthy eating modules, 4 physical activity modules, and 2 modules synthesizing information in 12 home visits (60-90 minutes) within the first 6 months. Up to 12 follow-up phone calls to each participant occurred within the second 6 months. Measures: Primary measures were dietary quality measured with weekday 24-hour recall and reported as Healthy Eating Index score (0-100) and physical activity measured with accelerometers (14 wear days) at baseline, 6, 12, and 24 months. Results: In total, 151 persons (81 adolescents and 70 adults; 44 families) were randomly assigned. At 12 months, significant improvement occurred in Healthy Eating Index scores for adults in the intervention group compared with controls (change, +8.6 vs −4.4; P < .01) and persisted at 24 months (+7.4 from baseline; P < .01). No differences were observed for adolescents and no significant differences occurred between groups for physical activity. Conclusion: This intervention produced sustained dietary quality improvement among adults but not among adolescents. Program outcomes are relevant to communities working to decrease cardiovascular risk among immigrant populations.

Background— Daily physical activity assessed by accelerometers represents a novel method to assess the impact of interventions on heart failure (HF) patients’ functional status. We hypothesized that daily activity varies by patient characteristics and correlates with established measures of HF severity in HF with preserved ejection fraction. Methods and Results— In this ancillary study of the NEAT-HFpEF trial (Nitrate’s Effects on Activity Tolerance in HF With Preserved Ejection Fraction), average daily accelerometer units (ADAU) and hours active per day were assessed during a 14-day period before starting isosorbide mononitrate or placebo (n=110). Baseline ADAU was negatively associated with age, female sex, height, and body mass index, and these variables accounted for 28% of the variability in ADAU ( P <0.007 for all). Adjusting for these factors, patients with lower ADAU were more likely to have had an HF hospitalization, orthopnea, diabetes mellitus and anemia, be treated with β-blockers, have higher ejection fraction, relative wall thickness and left atrial volume, and worse New York Heart Association class, HF-specific quality of life scores, 6-minute walk distance, and NT-proBNP (N-terminal pro-B-type natriuretic peptide; P <0.05 for all). Associations between hours active per day and clinical characteristics were similar. Relative to baseline, there were no significant associations between changes in ADAU or hours active per day and changes in standard functional assessments (New York Heart Association, quality of life, 6-minute walk distance, and NT-proBNP) with isosorbide mononitrate. Conclusions— Daily activity is a measure of HF-related and global functional status in HF with preserved ejection fraction. As compared with intermittently assessed standard HF assessments, change in daily activity may provide unique information about the impact of HF interventions on functional status. Clinical Trial Registration— URL: https://www.clinicaltrials.gov/ . Unique identifier: NCT02053493