Muscle fiber type is associated with obesity and weight loss.

The purpose of this study was to test the hypothesis that muscle fiber type is related to obesity. Fiber type was compared 1) in lean and obese women, 2) in Caucasian (C) and African-American (AA) women, and 3) in obese individuals who lost weight after gastric bypass surgery. When lean (body mass index 24.0 +/- 0.9 kg/m(2), n = 28) and obese (34.8 +/- 0.9 kg/m(2), n = 25) women were compared, there were significant (P < 0.05) differences in muscle fiber type. The obese women possessed fewer type I (41.5 +/- 1.8 vs. 54.6 +/- 1.8%) and more type IIb (25.1 +/- 1.5 vs. 14.4 +/- 1.5%) fibers than the lean women. When ethnicity was accounted for, the percentage of type IIb fibers in obese AA was significantly higher than in obese C (31.0 +/- 2.4% vs. 19.2 +/- 1.9%); fewer type I fibers were also found in obese AA (34.5 +/- 2.8% vs. 48.6 +/- 2.2%). These data are consistent with the higher incidence of obesity and greater weight gain reported in AA women. With weight loss intervention, there was a positive relationship (r = 0.72, P < 0.005) between the percentage of excess weight loss and the percentage of type I fibers in morbidly obese patients. These findings indicate that there is a relationship between muscle fiber type and obesity.

The effects of extreme nutritional conditions on the neurochemistry of reward and addiction.

weight loss is a frequent problem in space flights. We now claim that it may affect performance and drug-seeking behavior by altering midbrain neurochemistry. In food-deprived rats (20-30% underweight) basal extracellular dopamine levels in the nucleus accumbens decrease to 40-50% of normal and locomotion is depressed. However, amphetamine-induced dopamine release and locomotion are higher than in controls (1825% vs. 595% after a 25 micromoles d-amphetamine intraaccumbens infusion). The lower basal and the higher stimulated dopamine levels suggest that the neurotransmitter accumulates presynaptically in the accumbens of the underweight rats due to subnormal basal release. Psychostimulants are more rewarding for underweight subjects possibly because they release significantly more dopamine from elevated presynaptic stores into the accumbens. Consequently, weight loss can lead both to depression of performance and propensity to substance abuse. These effects should be considered when providing nutritional resources for space flights so that weight loss is limited. c 2001. Elsevier Science Ltd. All rights reserved.

Weight Loss expectations in obese patients seeking treatment at medical centers.

OBJECTIVE: To investigate weight loss expectations (expected 1-year BMI loss, dream BMI, and maximum acceptable BMI) in obese patients seeking treatment and to examine whether expectations differ by sex, weight, diet and weight history, age, psychological factors, and primary motivations for weight loss. RESEARCH METHODS AND PROCEDURES: 1891 obese patients seeking treatment in 25 Italian medical centers (1473 women; age, 44.7 +/- 11.0 years; BMI, 38.2 +/- 6.5 kg/m2) were evaluated. Diet and weight history, weight loss expectations, and primary motivation for seeking treatment (health or improving appearance) were systematically recorded. Psychiatric distress, binge eating, and body image dissatisfaction were tested by self-administered questionnaires (Symptom CheckList-90, Binge Eating Scale, and Body Uneasiness Test). RESULTS: In 1011 cases (53.4%), 1-year expected BMI loss was > or = 9 kg/m2, dream BMI was 26.0 +/- 3.4 kg/m2 (corresponding to a 32% loss), and maximum acceptable BMI was 29.3 +/- 4.4 kg/m2 (-23%). BMI and age were the strongest predictors of weight goals. weight loss necessary to reach the desired targets was largely in excess of weight loss observed during previous dieting. Psychiatric distress, body dissatisfaction, and binge eating did not predict weight loss expectations. The primary motivation for weight loss was concern for future or present health; women seeking treatment to improve appearance had a lower grade of obesity, were younger, and had first attempted weight loss at a younger age. DISCUSSION: Obese Italian patients had unrealistic weight loss expectations. There were significant disparities between patients' perceptions and physicians' weight loss recommendations of desirable treatment outcome.

The role of exercise for weight loss and maintenance.

Exercise provides a means of increasing energy expenditure and may help adjust energy balance for weight loss and maintenance. At least 30 minutes a day of moderate intensity aerobic exercise per day is recommended for weight loss and maintenance but greater amounts appear to increase the magnitude of weight loss and maintenance. Resistance training has recently been shown to have positive effects on body composition but does not typically show significant decreases in weight. Regardless of weight loss, both aerobic exercise and resistance training have been shown to diminish risk factors for cardiovascular disease and diabetes. Since exercise is only effective if sustained, behavioural strategies such as self-monitoring, goal setting, social support, etc. are used to help individuals start and maintain exercise programs and show improved results compared to exercise programs without behavioural strategies. The available evidence indicates that exercise is an important component of weight loss and perhaps the best predictor of weight maintenance.

Weight locus of control and weight-related attitudes and behaviors in an overweight population.

Construct of internal-external control of reinforcement led to the conceptualization of locus of control as a personality construct that can be used to predict behavior. More specific measures of locus of control in particular behavioral domains have followed. In the present study, the Weight Locus of Control Scale (WLOC) was used to predict weight-related attitudes and behaviors of overweight individuals, as well as their responses to health education materials (HEM) on weight loss. The WLOC scores predicted responses to baseline weight-related measures such as etiology of obesity, confidence in weight loss behaviors, and behavioral intention. In addition, WLOC scores predicted participants' reactions to the HEM, as well as the actual number of weight loss ideas from the HEM that the participants tried by the 1-month follow-up assessment. The results are discussed in terms of the validity of the WLOC and implications for future development of effective HEM.

Exercise is required for visceral fat loss in postmenopausal women with type 2 diabetes.

This study examined the effects of aerobic exercise without weight loss, a hypocaloric high monounsaturated fat diet, and diet plus exercise (D+E) on total abdominal and visceral fat loss in obese postmenopausal women with type 2 diabetes. Thirty-three postmenopausal women (body mass index, 34.6 +/- 1.9 kg/m(2)) were assigned to one of three interventions: a hypocaloric high monounsaturated fat diet alone, exercise alone (EX), and D+E for 14 wk. Aerobic capacity, body composition, abdominal fat distribution (magnetic resonance imaging), glucose tolerance, and insulin sensitivity were measured pre- and postintervention. Body weight ( approximately 4.5 kg) and percent body fat ( approximately 5%) were decreased (P < 0.05) with the D and D+E intervention, whereas only percent body fat ( approximately 2.3%) decreased with EX. Total abdominal fat and sc adipose tissue (SAT) were reduced with the D and D+E interventions (P < 0.05), whereas visceral adipose tissue (VAT) decreased with the D+E and EX intervention, but not with the D intervention. EX resulted in a reduction in total abdominal fat, VAT, and SAT (P < 0.05) despite the lack of weight loss. The reductions in total abdominal fat and SAT explained 32.7% and 9.7%, respectively, of the variability in the changes in fasting glucose levels, whereas the reductions in VAT explained 15.9% of the changes in fasting insulin levels (P < 0.05). In conclusion, modest weight loss, through either D or D+E, resulted in similar improvements in total abdominal fat, SAT, and glycemic status in postmenopausal women with type 2 diabetes; however, the addition of exercise to diet is necessary for VAT loss. These data demonstrate the importance of exercise in the treatment of women with type 2 diabetes.

The relationship of cancer symptom clusters to depressive affect in the initial phase of palliative radiation.

Research on comorbidity across cancer symptoms, including pain, fatigue, and depression, could suggest if crossover effects from symptom-specific interventions are plausible. Secondary analyses were conducted on a survey of 268 cancer patients with recurrent disease from a northeastern U.S. city who were initiating palliative radiation for bone pain. Moderator regression analyses predicted variation in depressive affect that could be attributed to symptom clusters. Patients self-reported difficulty controlling each physical symptom over the past month on a Likert scale and depressive symptoms on a validated depression measure (Center for Epidemiologic Studies-Depression [CES-D]) over the past week on a four-category scale. An index of depressive affect was based on items of negative and positive affect from the CES-D. In predicting depressive affect, synergistic interactions of pain with fever, fatigue, and weight loss suggest separate pathways involving pain. A similar interaction with fever occurs when nausea was tested in place of pain. Further, the interaction between pain and fatigue is similar in form to the interaction between difficulty breathing and fatigue (when sleep is not a problem). Follow-up to the latter interaction reveals: 1) additional moderation by hypertension and palliative radiation to the hip/pelvis; and 2) a similar cluster not involving hypertension when appetite problems and weight loss were tested in place of fatigue. The significance and form of these interactions are remarkably consistent. Similar sickness mechanisms could be generating: 1) pain and nausea during fever; 2) pain and fatigue during weight loss; and 3) pain and breathing difficulty when fatigue is pronounced. Crossover effects from symptom-specific interventions appear promising.

High dairy-protein versus high mixed-protein energy restricted diets - the effect on bone turnover and calcium excretion in overweight adults.

Background - A moderate exchange of some dietary carbohydrate for protein appears to have metabolic and weight loss advantages in human studies. This dietary strategy raises safety concerns for bone health. The impact of dietary calcium in high protein diets on bone turnover has not been investigated. Objective - This study examined the effect of protein source and calcium content in high protein, energy restricted diets on calcium excretion and bone metabolism in 50 overweight adults (BMI 33.4 +/- 2.1 kg/m(2)). Design - The parallel study consisted of a 12-week energy restriction phase followed by a four-week energy balance phase. Subjects were randomised to one of two isoenergetic (5.5 MJ/d, 34% energy from protein, 41% from carbohydrate and 24% from fat) diets; high dairy protein (DP, 2400mg Ca/d) or high mixed protein (MP, 500mg Ca/d). Outcomes - Energy restriction was the primary determinant of weight loss (-9.7 +/- 3.8 kg, P<0.01) with no significant effect of protein source. Twenty-four hour calcium excretion decreased during both interventions (-1.09 +/- 0.23 mmol/day, P<0.009). By week 16 the MP diet had a 40% larger increase in deoxypyridinoline (a bone turnover marker) compared to the DP diet (P=0.008). Osteocalcin (a marker of bone formation) increased from week zero to 16 in the MP diet only (+2.22 ng/ml P=0.001). Conclusions - Overall, the DP diet has a modest advantage over MP diet by reducing the accelerated bone turnover associated with weight loss.