Reno Diet Heart Study

BACKGROUND:

The treatment of obesity has met with limited success and clinically significant weight losses have been difficult to achieve and maintain. Screening to determine which patient will benefit most from treatment, emphasis on maintenance of weight loss and understanding individual weight trends and goals, all have demonstrated significant impact on long-term treatment outcome. Stunkard established a new classification of obesity according to severity and predicted outcome to treatment, distinguishing mild and moderate overweight from severe forms of obesity. Those who were classified as mildly obese were those who were most likely to be successful in traditional forms of treatment. A comprehensive study of this mildly obese population and normal weight maintenance behaviors provided important information on which to build future treatment interventions and/or effective strategies. This would be of particular importance in the prevention of obesity and progressive escalation of the obese state.

DESIGN NARRATIVE:

Subjects were studied retrospectively by history and prospectively in their natural setting for five years. A 2 x 2 x 5 multifactorial design was used where sex (males versus females) and weight (obese versus normal) were crossed with five different age groups according to decades (20-29, 30-39, 40-49, 50-59 and 60 or more years) respectively. A total of 50 (25 normal and 25 obese) were recruited for each age/sex group. Dependent variables included: weight, weight trends, fluctuation, body composition; diet; activity or exercise; weight maintenance behaviors and adaptive responses; general well-being, emotional states, psychopathology; routine blood and urinalyses; cardiovascular disease risk profile including lipids, blood pressure, sodium, potassium, calcium and phosphorus levels, diet, smoking, alcohol and caffeine use, onset of menopause and changes in medical status or medication use. Comprehensive assessment was done yearly.

The study was renewed in 1992 to extend follow-up and evaluation of the RENO Diet Heart Study and to complete and extend testing of the primary hypotheses. The three major hypotheses tested included: 1) weight fluctuations affected cardiovascular disease (CVD) risk factors over and above weight change alone; 2) weight changes, fluctuations and patterns interacted with nutritional, behavioral, psychological and medical factors, but these factors also affected CVD risk independent of weight; and 3) retrospective, self-reported weights, fluctuations and patterns were predictive of prospective weights and weight fluctuations.