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Biomedical subjects

Richard L Atkinson

Publications and source records attributed to Richard L Atkinson.

5 recordsLinked to original sources
PubMed2003

Weight loss with self-help compared with a structured commercial program: a randomized trial.

CONTEXT: Although commercial weight loss programs provide treatment to millions of clients, their efficacy has not been evaluated in rigorous long-term trials. OBJECTIVE: To compare weight loss and health benefits achieved and maintained through self-help weight loss vs with a structured commercial program. DESIGN AND SETTING: A 2-year, multicenter randomized clinical trial with clinic visits at 12, 26, 52, 78, and 104 weeks conducted at 6 academic research centers in the United States between January 1998 and January 2001. PARTICIPANTS: Overweight and obese men (n = 65) and women (n = 358) (body mass index, 27-40) aged 18 to 65 years. INTERVENTION: Random assignment to either a self-help program (n = 212) consisting of two 20-minute counseling sessions with a nutritionist and provision of self-help resources or to a commercial weight loss program (n = 211) consisting of a food plan, an activity plan, and a cognitive restructuring behavior modification plan, delivered at weekly meetings. MAIN OUTCOME MEASURES: Weight change was the primary outcome measure. Secondary outcomes included waist circumference, body mass index, blood pressure, serum lipids, glucose, and insulin levels. RESULTS: At 2 years, 150 participants (71%) in the commercial group and 159 (75%) in the self-help group completed the study. In the intent-to-treat analysis, mean (SD) weight loss of participants in the commercial group was greater than in the self-help group at 1 year (-4.3 [6.1] kg vs -1.3 [6.1] kg, respectively; P<.001) and at 2 years (-2.9 [6.5] kg vs -0.2 [6.5] kg, respectively; P<.001). Waist circumference (P =.003) and body mass index (P<.001) decreased more in the commercial group. Changes in blood pressure, lipids, glucose, and insulin levels were related to changes in weight in both groups, but between-group differences in biological parameters were mainly nonsignificant by year 2. CONCLUSION: The structured commercial weight loss program provided modest weight loss but more than self-help over a 2-year period.

Adult↗
PubMed2003

Measurement of nutritional status in simulated microgravity by bioelectrical impedance spectroscopy.

The potential of bioelectrical impedance spectroscopy (BIS) for assessing nutritional status in spaceflight was tested in two head-down-tilt bed-rest studies. BIS-predicted extracellular water (ECW), intracellular water (ICW), and total body water (TBW) measured using knee-elbow electrode placement were compared with deuterium and bromide dilution (DIL) volumes in healthy, 19- to 45-yr-old subjects. BIS was accurate during 44 h of head-down tilt with mean differences (BIS - DIL) of 0-0.1 kg for ECW, 0.3-0.5 for ICW, and 0.4-0.6 kg for TBW (n = 28). At 44 h, BIS followed the within-individual change in body water compartments with a relative prediction error (standard error of the estimate/baseline volume) of 2.0-3.6% of water space. In the second study, BIS did not detect an acute decrease (-1.41 +/- 0.91 kg) in ICW secondary to 48 h of a protein-free, 800 kcal/day diet (n = 18). BIS's insensitivity to ICW losses may be because they were predominantly (65%) localized to the trunk and/or because there was a general failure of BIS to measure ICW independently of ECW and TBW. BIS may have potential for measuring nutritional status during spaceflight, but its limitations in precision and insensitivity to acute ICW changes warrant further validation studies.

Adult↗
PubMed2002

Human adenovirus Ad-36 promotes weight gain in male rhesus and marmoset monkeys.

Although obesity has multiple etiologies, an overlooked possibility is an infectious origin. We previously identified two viruses, SMAM-1, an avian adenovirus (Ad), and Ad-36, a human adenovirus, that produce a syndrome of visceral obesity, with paradoxically decreased serum cholesterol and triglycerides in chickens and mice. In the two studies presented in this paper, we used nonhuman primates to investigate the adiposity-promoting potential of Ad-36. In study 1, we observed spontaneously occurring Ad-36 antibodies in 15 male rhesus monkeys, and a significant longitudinal association of positive antibody status with weight gain and plasma cholesterol lowering during the 18 mo after viral antibody appearance. In study 2, which was a randomized controlled experiment, three male marmosets inoculated with Ad-36 had a threefold body weight gain, a greater fat gain and lower serum cholesterol relative to baseline (P <0.05) than three uninfected controls at 28 wk postinoculation. These studies illustrate that the adiposity-promoting effect of Ad-36 occurs in two nonhuman primate species and demonstrates the usefulness of nonhuman primates for further evaluation of Ad-36-induced adiposity.

Adenoviridae Infections↗
PubMed2002

Prior exercise increases subsequent utilization of dietary fat.

PURPOSE: Exercise appears to offer protection against weight gain, perhaps related to its effects on fat metabolism. Previous work in rats has shown that interventions resulting in a negative energy balance lead to alterations in the trafficking of dietary fat. This study was undertaken to determine whether exercise after an overnight fast would alter the partitioning of dietary fat between oxidation and storage. METHODS: Seven female subjects (age = 26 +/- 1 yr, BMI = 21 +/- 1 kg x m(-2); mean +/- SEM) were recruited for three visits: rest, light, and heavy exercise. Stationary cycle exercise sessions were calculated to use 1,250 kJ and were done in a whole-body calorimeter. Dietary fat oxidation was calculated from the recovery of (13)C-oleate corrected for acetate sequestration and d(31)-palmitate given in a liquid meal 30 min after the completion of exercise. RESULTS: Cumulative oxidation of (13)C-oleate at 11.5 h postdose was significantly greater during the heavy exercise (49 +/- 4%) trial than both the light exercise (39 +/- 4%) and the rest trials (34 +/- 4%) (P < 0.005). Oxidation of d(31)-palmitate recovery at 11.5 h postdose was not different during the heavy exercise (12 +/- 1%), light exercise (11 +/- 1%), and rest trials (10 +/- 1%). CONCLUSIONS: These data illustrate that exercise has the ability to alter the trafficking of dietary fat. Furthermore, the effect of exercise is dependent on the type of fatty acid.

Adult↗