The Study of Novel Approaches for Prevention (SNAP) is randomized trial designed to test whether behavioral interventions based on self-regulation can prevent weight gain in young adults (18-35 years; body mass index (BMI) 21-30 kg/m2). Two different self-regulation interventions for weight gain prevention will be compared in this trial; one intervention will focus on making small, consistent, changes in eating and exercise behavior to prevent weight gain or reverse weight gain if it occurs, whereas the other will emphasize larger changes in eating and exercise that occur periodically, with a goal of producing weight loss and thereby providing a buffer against anticipated weight gains. The primary aim of the trial is to test whether the magnitude of weight gain from baseline across an average three-year follow-up differs across the three groups, with the hypotheses that weight gain will be greater in the Control group than in either intervention and greater in the Small Changes than Large Changes group. SNAP-E (Extension) will determine whether the effects of the intervention can be maintained over an additional 3 years (i.e. through a total of 6 years).
Young adults, aged 20-35 years, experience the greatest rate of weight gain, averaging 1-2 lbs/yr. Over time, this weight gain is associated with a worsening in cardiovascular disease risk factors and an increase in the prevalence of metabolic syndrome. Given the difficulties in producing sustained weight loss later in life, preventing weight gain from occurring during this critical period is key to curbing the obesity epidemic. The Study of Novel Approaches for Prevention (SNAP) is a 2-center randomized trial designed to test whether behavioral interventions based on self-regulation can prevent weight gain in young adults (18-35 years; body mass index (BMI) 21-30 kg/m2). Approximately 600 participants will be recruited over two years and randomly assigned to a control condition (N=200), self-regulation with small changes (N=200) or self-regulation with large changes (N=200). The Small Changes group will be taught to make small, consistent, changes in eating and exercise behavior to prevent weight gain or reverse weight gain if it occurs whereas the Large Changes group will emphasize periodic, larger changes in eating and exercise, with a goal of producing weight loss and thereby providing a buffer against anticipated weight gain. The primary aim of the trial is to test whether the magnitude of weight gain from baseline across an average planned follow-up of three years differs across the three groups, with a priori hypotheses that weight gain will be greater in the Control group than in either intervention and greater in the Small Changes than Large Changes group. Secondary aims are to compare the three groups on a) the proportion of participants in the three groups who gain less than 1 pound over the planned follow-up, b) the mean difference in weight gain from baseline to 24-month follow-up, c) the changes in behaviors and psychosocial measures (diet, physical activity, dietary restraint, frequency of self-weighing,depression, and occurrence of abnormal eating behaviors), and d) the changes in cardiovascular disease risk factors (blood pressure, lipids, insulin sensitivity, and waist circumference). The trial will also examine the association among changes in behaviors, weight, and cardiovascular disease risk factors and examine variables that may moderate the effects of the intervention (including gender, ethnicity, initial BMI, age) and potential mediators of the effects of the intervention (including changes in diet, activity, and self-regulatory behaviors). SNAP is member of the Early Adult Reduction in Weight Through Lifestyle Interventions (EARLY) consortium of clinical trials funded by the National Heart, Lung, and Blood Institute.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
DOUBLE
Enrollment
599
The Self-Regulation Plus Small Behavior Changes Intervention will focus on making small changes in diet and physical activity on a daily basis to prevent weight gain. Diet: The dietary approach used in this group is to identify small changes in what and how much participants eat each day. The general concept is that these are small, manageable changes that will produce small reductions in overall intake and can easily be made on a daily basis and maintained over time. Exercise: At the start of the program, participants will be given a pedometer and asked to record their current or baseline number of steps. They will then be given the goal of increasing their daily steps by 2000 steps per day over this baseline level.
The focus of this intervention group will be on periodically making large changes in diet and physical activity, with the goal of losing 5-10 pounds to buffer against the weight gain that often occurs during young adulthood. Diet: Individuals with a BMI of 21-24.9 kg/m2 will be encouraged to lose 5 pounds; those with a BMI of 25-30 kg/m2 will be encouraged to lose 10 pounds. Exercise: The Large Changes group will be instructed to gradually increase their minutes of physical activity until achieving 250 minutes per week (5 days/week with 50 minutes per day) using activities similar in intensity to brisk walking.
University of North Carolina
Chapel Hill, North Carolina, United States
The Miriam Hospital
Providence, Rhode Island, United States
Weight Changes From Baseline Over Follow-up.
Mean weight change from baseline across an average planned follow-up of three years. These mean changes will be compared among the three arms of the trial.
Time frame: 3 years
Weight Gain 1 Pound or More at Any Time Over Follow-up
Average over time (average follow-up of 3 years) of the percent of participants within each arm of the trial who gain 1 pound or more at each visit. These percentages will be compared among the three arms generalized estimating equations. Note that weight changes in units of pounds were used to define this outcome so that it may be more clear to participants. Elsewhere in the protocol, weight is reported in kilograms. Percentages at each visit are the percent who gained 1 pound or more from baseline among all who were weighed at that visit. Participants were assigned values of 0 or 1 at each visit depending on their weight gain status.
Time frame: 3 years
Mean Weight Changes
Mean differences in weight changes among intervention groups at 24 months post-randomization
Time frame: 2 years
Mean Changes in Systolic Blood Pressure
Compare changes in systolic blood pressure across the three intervention groups
Time frame: Measured at 2 Years
Mean Changes From Baseline in Diastolic Blood Pressure
Change from baseline to 2 years in diastolic blood pressure
Time frame: 2 years
Mean Changes From Baseline to 2 Years in Total Cholesterol
Mean changes from baseline to 2 years in total cholesterol among participants with Year 2 measurements (mg/dl)
Time frame: 2 years
Obesity
Percentage of those participants whose body mass index at baseline was less than 30 kg/m2 who subsequently transitioned to a body mass index of 30 kg/m2 or more (i.e. met criteria for obesity) sometime during 3 years of follow-up (i.e. at least one visit). Percentages will be compared among the three arms of the trial and summarized with odds ratios Participants were assigned values of 0 or 1 at each exam depending on their obesity level. Inference is based on generalized estimating equations.
Time frame: 3 years
Dietary Restraint: Mean Change From Baseline to 2 Years
The Eating Inventory (Stunkard, 1988) is a 51-item self-report instrument, was used to assess the subscale of dietary restraint (e.g., degree of conscious control exerted over eating behaviors; range from 0-21 with higher scores reflecting greater levels of restraint). Reference: Stunkard, A. J. M., S. (1988). Eating Inventory Manual. New York: Psychological Corporation.
Time frame: 2 years
Disinhibition
The Eating Inventory (TFEQ(Stunkard, 1988), a 51-item self-report instrument, was used to assess the subscale of disinhibition (e.g., susceptibility to loss of control over eating; range 0-16, with higher scores reflecting greater levels of disinhibition). REF: Stunkard, A. J. M., S. (1988). Eating Inventory Manual. New York: Psychological Corporation.
Time frame: Changes at 2 years
Flexible Dietary Control
Flexible control is characterized by a balanced approach to eating (e.g., taking smaller portions to control weight, engaging in healthy compensation) and is associated with better weight management outcomes (Westenhoefer, Stunkard, \& Pudel, 1999). Scores range from 0 to 12 with higher scores reflecting greater levels of flexible control. REF: Westenhoefer, J., Stunkard, A. J., \& Pudel, V. (1999). Validation of the flexible and rigid control dimensions of dietary restraint. Int J Eat Disord, 26(1), 53-64.
Time frame: Changes from baseline to 2 years
Rigid Dietary Control
Rigid control is characterized by an all-or-nothing inflexibility around dietary rules (e.g., strict calorie counting, with guilt following if calorie-dense foods are consumed) that is associated with poor weight outcomes and more binge eating (Westenhoefer, Stunkard, \& Pudel, 1999). Scores range from 0 to 16 with higher scores reflecting greater rigid control. REF: Stunkard, A. J. M., S. (1988). Eating Inventory Manual. New York: Psychological Corporation.
Time frame: Changes from baseline to 2 years
General Health Index
The General Health Index, a one-item question from the CDC's Health-Related Quality of Life measure (Measuring Healthy Days, 2000) required participants to report whether in general their health is excellent (1), very good (2), good (3), fair (4), or poor (5). Lower scores denotes better outcomes. Ref: Measuring Healthy Days. (2000). Atlanta, Georgia: Centers for Disease Control and Prevention
Time frame: Changes from baseline to 2 years
Mean Changes in High Density Lipoprotein Cholesterol (HDL-C)
Mean changes in HDL-C from baseline to year 2 in (mg/dl) for compared among the 3 arms using analysis of variance
Time frame: 2 years
Mean Changes in Low Density Lipoprotein Cholesterol (LDL-C)
Mean changes between baseline and 2 years in low density lipoprotein cholesterol: LDL-c (mg/dl)
Time frame: 2 years
Mean Change in Fasting Glucose From Baseline to 2 Years
Mean change in fasting glucose from baseline to 2 years in mg/dl for all participants with year 2 measures
Time frame: 2 years
Mean Change in Fasting Insulin From Baseline to 2 Years
Mean change in fasting insulin (uU/ml) from baseline to 2 years
Time frame: 2 years
Depression Symptomatology
Mean changes in the Center for Epidemiologic Studies Depression (CES-C) Scale. Reference: Turvey, C. L., Wallace, R. B., \& Herzog, R. (1999). A revised CES-D measure of depressive symptoms and a DSM-based measure of major depressive episodes in the elderly. Int Psychogeriatr, 11(2), 139-148. 20 item questionnaire with a possible range of scores is zero to 60, and higher scores indicating the presence of more symptomatology.
Time frame: 2 years
Insulin Resistance
We calculated homeostatic model assessment insulin resistance (HOMA-IR): fasting glucose in (mg/dl) \* fasting insulin in (uU/mL).
Time frame: Change from baseline to 2 years
Total Energy Dietary Intake Per Day (Kcals)
Dietary intake was assessed using the 2005 Block Food Frequency Questionnaire (Block FFQ) at baseline and 2 years. This validated, quantitative 110-food item questionnaire is designed to assess relative intake of energy. REF: Block G, Woods M, Potosky A, Clifford C. Validation of a self-administered diet history questionnaire using multiple diet records. J Clin Epidemiol 1990; 43:1327-1335.
Time frame: Changes from baseline to 2 years in kilocalories
Change in Waist Circumference (cm)
Waist circumference will be measured using a Gulik tape measure and following a standardized protocol. Two measures of waist circumference will be taken; if the difference exceeds 1.0 cm, a third measure will be taken. Changes are measured from baseline to year 2.
Time frame: Change from baseline to 2 years
Self-weighing
Number of days per week the participant reports weighing themselves. This is divided into two groups: 1) more than once per week and 2) no more than once per week
Time frame: 2 years
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