A study of patients more than 25 years of age with body mass index above 30, dyslipidemia, hypertension, and fasting glucose averaging 115 mg/ dL is performed. They have adipose tissue abnormalities including increased non-esterified fatty acid release, altered adipokines with decreased adiponectin, greater proinflammatory cytokine release, and diminished peroxisome proliferator-activated receptor gamma (PPARg) function. Which of the following is the best initial therapeutic intervention for these patients?