Metabolic and Bio-behavioral Effects of Following Recommendations in the Dietary Guidelines for Americans

This study, at the Western Human Nutrition Research Center (WHNRC), will focus on whether or not achieving and maintaining a healthy body weight is the most important health promoting recommendation of the Dietary Guidelines for Americans (DGA).The investigators hypothesize that improvement in cardiometabolic risk factors resulting from eating a DGA style diet will be greater in people whose energy intake is restricted to result in weight loss compared to those who maintain their weight. The investigators further propose that during a state of energy restriction, a higher nutrient quality diet such as the DGA style diet pattern, will result in greater improvement in cardiometabolic risk factors compared to a typical American diet (TAD) pattern that tends to be lower nutrient quality (more energy-dense and less nutrient-rich.)

This will be a 28-week study including pre-diet testing (week 1), an 8-week controlled feeding period, post-diet testing (week 10), a follow-up period of dietary education and observation, and end of study testing (week 28). During the 8 week feeding, participants will be randomly assigned one of the following diets: 1. DGA Mediterranean diet pattern at sufficient energy level to maintain body weight (energy balance) 2. DGA Mediterranean diet pattern at a moderately reduced energy level (negative energy balance) 3. TAD diet pattern at a moderately reduced energy level (negative energy balance) In the follow-up phase, the investigators will evaluate how multiple factors may influence body weight management, including previous dietary exposure, as well as the role of cognitive function, executive function, genetics, habitual diet, physical activity, eating behavior, stress and stress responsivity, metabolic flexibility and gut microbiome.