Stella L. Volpe

Appropriate Intervention Strategies for Weight Loss and Prevention of Weight Regain for Adults

In excess of 55% of adults in the United States are classified as either overweight (body mass index = 25-29.9 kg.m(-2)) or obese (body mass index > or = 30 kg.m(-2)). To address this significant public health problem, the American College of Sports Medicine recommends that the combination of reductions in energy intake and increases in energy expenditure, through structured exercise and other forms of physical activity, be a component of weight loss intervention programs. An energy deficit of 500-1000 kcal.d-1 achieved through reductions in total energy intake is recommended. Moreover, it appears that reducing dietary fat intake to <30% of total energy intake may facilitate weight loss by reducing total energy intake. Although there may be advantages to modifying protein and carbohydrate intake, the optimal doses of these macronutritents for weight loss have not been determined. Significant health benefits can be recognized with participation in a minimum of 150 min (2.5 h) of moderate intensity exercise per week, and overweight and obese adults should progressively increase to this initial exercise goal. However, there may be advantages to progressively increasing exercise to 200-300 min (3.3-5 h) of exercise per week, as recent scientific evidence indicates that this level of exercise facilitates the long-term maintenance of weight loss. The addition of resistance exercise to a weight loss intervention will increase strength and function but may not attenuate the loss of fat-free mass typically observed with reductions in total energy intake and loss of body weight. When medically indicated, pharmacotherapy may be used for weight loss, but pharmacotherapy appears to be most effective when used in combination with modifications of both eating and exercise behaviors. The American College of Sports Medicine recommends that the strategies outlined in this position paper be incorporated into interventions targeting weight loss and the prevention of weight regain for adults.

Magnesium in Disease Prevention and Overall Health

Magnesium is the fourth most abundant mineral and the second most abundant intracellular divalent cation and has been recognized as a cofactor for >300 metabolic reactions in the body. Some of the processes in which magnesium is a cofactor include, but are not limited to, protein synthesis, cellular energy production and storage, reproduction, DNA and RNA synthesis, and stabilizing mitochondrial membranes. Magnesium also plays a critical role in nerve transmission, cardiac excitability, neuromuscular conduction, muscular contraction, vasomotor tone, blood pressure, and glucose and insulin metabolism. Because of magnesiums many functions within the body, it plays a major role in disease prevention and overall health. Low levels of magnesium have been associated with a number of chronic diseases including migraine headaches, Alzheimers disease, cerebrovascular accident (stroke), hypertension, cardiovascular disease, and type 2 diabetes mellitus. Good food sources of magnesium include unrefined (whole) grains, spinach, nuts, legumes, and white potatoes (tubers). This review presents recent research in the areas of magnesium and chronic disease, with the goal of emphasizing magnesiums role in disease prevention and overall health.

Rationale, design and methods for process evaluation in the HEALTHY study.

The HEALTHY study was a multi-site randomized trial designed to determine whether a 3-year school-based intervention targeting nutrition and physical activity behaviors could effectively reduce risk factors associated with type 2 diabetes in middle school children. Pilot and formative studies were conducted to inform the development of the intervention components and the process evaluation methods for the main trial. During the main trial, both qualitative and quantitative assessments monitored the fidelity of the intervention and motivated modifications to improve intervention delivery. Structured observations of physical education classes, total school food environments, classroom-based educational modules, and communications and promotional campaigns provided verification that the intervention was delivered as intended. Interviews and focus groups yielded a multidimensional assessment of how the intervention was delivered and received, as well as identifying the barriers to and facilitators of the intervention across and within participating schools. Interim summaries of process evaluation data were presented to the study group as a means of ensuring standardization and quality of the intervention across the seven participating centers. Process evaluation methods and procedures documented the fidelity with which the HEALTHY study was implemented across 21 intervention schools and identified ways in which the intervention delivery might be enhanced throughout the study.

Magnesium, the Metabolic Syndrome, Insulin Resistance, and Type 2 Diabetes Mellitus

Magnesium is an essential mineral and has been established as a cofactor for over 300 metabolic reactions in the body. Some research has indicated that lower intakes of magnesium and lower serum magnesium concentrations may lead to and are associated with the metabolic syndrome, insulin resistance, and/or type 2 diabetes mellitus. The goal of this review is to examine the research conducted on: 1) magnesium status, metabolic syndrome, insulin resistance, and type 2 diabetes mellitus, and 2) the effects of magnesium intake and/or supplementation on metabolic syndrome, insulin resistance, and type 2 diabetes mellitus. To make this review as current as possible, the majority of research articles reviewed were from 2000 to the present.

The effects of the HEALTHY study intervention on middle school student dietary intakes

BackgroundThe HEALTHY study was designed to respond to the alarming trends in increasing rates of overweight, obesity, and type 2 diabetes mellitus in youth. The objective of this analysis was to examine the effects of the HEALTHY study on student self-reported dietary intakes (energy, macronutrients and grams consumed of selected food groups).MethodsHEALTHY was a cluster-randomized study in 42 public middle schools. Students, n = 3908, self-reported dietary intake using the Block Kids Questionnaire. General linear mixed models were used to analyze differences in dietary intake at the end of the study between intervention and control schools.ResultsThe reported average daily fruit consumption was 10% higher at the end of the study in the intervention schools than in the control schools (138 g or approximately 2 servings versus 122 g, respectively, p = 0.0016). The reported water intake was approximately 2 fluid ounces higher in the intervention schools than in the control (483 g versus 429 g respectively; p = 0.008). There were no significant differences between intervention and control for mean intakes of energy, macronutrients, fiber, grains, vegetables, legumes, sweets, sweetened beverages, and higher- or lower-fat milk consumption.ConclusionThe HEALTHY study, a five-semester middle school-based intervention program that integrated multiple components in nutrition, physical education, behavior change, and social marketing-based communications, resulted in significant changes to students reported fruit and water intake. Subsequent interventions need to go beyond the school environment to change diet behaviors that may affect weight status of children.Clinical Trials RegistrationNCT00458029

Rationale, design and methods of the HEALTHY study physical education intervention component

The HEALTHY primary prevention trial was designed to reduce risk factors for type 2 diabetes in middle school students. Middle schools at seven centers across the United States participated in the 3-year study. Half of them were randomized to receive a multi-component intervention. The intervention integrated nutrition, physical education (PE) and behavior changes with a communications strategy of promotional and educational materials and activities. The PE intervention component was developed over a series of pilot studies to maximize student participation and the time (in minutes) spent in moderate-to-vigorous physical activity (MVPA), while meeting state-mandated PE guidelines. The goal of the PE intervention component was to achieve ⩾150 min of MVPA in PE classes every 10 school days with the expectation that it would provide a direct effect on adiposity and insulin resistance, subsequently reducing the risk of type 2 diabetes in youth. The PE intervention component curriculum used standard lesson plans to provide a comprehensive approach to middle school PE. Equipment and PE teacher assistants were provided for each school. An expert in PE at each center trained the PE teachers and assistants, monitored delivery of the intervention and provided ongoing feedback and guidance.

Fatness, Fitness, and Cardiometabolic Risk Factors among Sixth-Grade Youth

PURPOSE Examine whether cardiometabolic risk factors are predicted by fitness or fatness among adolescents. METHODS Participants are 4955 (2614 female) sixth-grade students with complete data from 42 US middle schools. Fasting blood samples were analyzed for total cholesterol, HDL- and LDL-cholesterol, triglyceride, glucose, and insulin concentrations. Waist circumference and blood pressure were assessed. Body mass index (BMI) was categorized as normal weight, overweight, or obese as a measure of fatness. Fitness was assessed using the multistage shuttle test and was converted into gender-specific quintiles. Gender-specific regression models, adjusted for race, pubertal status, and household education, were run to identify whether BMI group predicted risk factors. Models were repeated with fitness group and both fitness and fatness groups as predictors. RESULTS Means for each risk factor (except HDL, which was the reverse) were significantly higher (P < 0.0001) with increased fatness and differed across all BMI groups (P < 0.001). Waist circumference, LDL-cholesterol, triglycerides, diastolic blood pressure, and insulin were inversely associated with fitness (P < 0.001). When both fatness and fitness were included in the model, BMI was associated (P < 0.001) with almost all cardiometabolic risk factors; fitness was only associated with waist circumference (both genders), LDL-cholesterol (males), and insulin (both genders). Other associations between fitness and cardiometabolic risk factors were attenuated after adjustment for BMI group. CONCLUSIONS Both fatness and fitness are associated with cardiometabolic risk factors among sixth-grade youth, but stronger associations were observed for fatness. Although maintaining high levels of fitness and preventing obesity may positively affect cardiometabolic risk factors, greater benefit may be obtained from obesity prevention.

Effect of Diet and Exercise on Body Composition, Energy Intake and Leptin Levels in Overweight Women and Men

Objective: To investigate the effect of diet alone (D), exercise alone (E), and a combination of diet and exercise (DE) on body weight, body composition, energy intake, blood pressure, serum lipid and leptin levels, and fitness levels in mildly obese sedentary women and men. Design: The three interventions were compared in a randomized longitudinal study design. The exercise programs were supervised for six months, after which participants in E and DE were provided with exercise equipment to take home. Subjects: 90 adult overweight women and men (age: 44.2 ± 7.2 years; BMI = 30.5 ± 2.7 kg/m2). Measurements: Body weight, body composition, waist and hip circumferences, blood pressure, serum lipid levels, and fitness levels were evaluated at 0, 3, 6, 9, and 12 months. Serum leptin concentrations were measured at 0 and 6 months only. Results: At 6 and 9 months in women, and 9 months in men, DE demonstrated a significant loss of body weight compared to both D and E (p < 0.05). Serum leptin levels significantly decreased from baseline to 6 months in women in D (p = 0.05) and DE (p = 0.0003) and men in E (p = 0.038). At one year, no significant differences existed among groups in any of the measures. Conclusion: A combination of diet and exercise resulted in a significant decrease in body weight in women and men; but this decrease was not maintained at one year follow-up. Serum leptin concentrations showed significant within-group decreases, but were not different among groups. A supervised diet and exercise program is effective for weight loss; however, once intensive participant-investigator and participant-participant contact is discontinued, weight regain ensures.

Iron, thermoregulation, and metabolic rate

Iron plays an important role, not only in oxygen delivery to the tissues, but also as a cofactor with several enzymes involved in energy metabolism and thermoregulation. As a result, much research has been dedicated to understanding the ramifications of iron depletion and iron deficiency anemia on the physiological functions of these enzymes. There is evidence to suggest that iron depletion and iron deficiency anemia cause physiological changes in the body not only during exercise, but also under resting conditions. Both rat and human studies have produced results revealing elevated levels of norepinephrine in the blood and urine of iron-deficient anemic subjects. These studies also provide evidence to suggest that elevation in metabolic rate may ultimately lead to slower growth rates and lower body weights in iron-deficient anemic animals and humans. The focus of this review is on the effects of iron deficiency on metabolic rate and thermoregulation. Prior to this discussion, a brief background on iron is presented.

HEALTHY Intervention: Fitness, Physical Activity, and Metabolic Syndrome Results

PURPOSE This study aimed to assess the effect of the HEALTHY intervention on the metabolic syndrome (Met-S), fitness, and physical activity levels of US middle-school students. METHODS Cluster randomized controlled trial conducted in 42 (21 intervention) US middle schools. Participants were recruited at the start of sixth grade (2006) when baseline assessments were made, with post-assessments made 2.5 yr later at the end of eighth grade (2009). The HEALTHY intervention had four components: 1) improved school food environment, 2) physical activity and eating educational sessions, 3) social marketing, and 4) revised physical education curriculum. Met-S risk factors, 20-m shuttle run (fitness), and self-reported moderate to vigorous physical activity (MVPA) were assessed at each time point. Ethnicity and gender were self-reported. Obesity status (normal weight, overweight, or obese) was also assessed. RESULTS At baseline, 5% of the participants were classified with Met-S, with two-thirds of the males and one-third of the females recording below average baseline fitness levels. Control group participants reported 96 min of MVPA at baseline with 103 min reported by the intervention group. There were no statistically significant (P < 0.05) differences in Met-S, fitness, or MVPA levels at the end of the study after adjustment for baseline values and confounders. There were no differences in any ethnic, obesity, or ethnic × obesity subgroups for either gender. CONCLUSIONS The HEALTHY intervention had no effect on the Met-S, fitness, or physical activity levels. Approaches that focus on how to change physical activity, fitness, and Met-S using nonschool or perhaps in addition to school based components need to be developed.