Increasing low-energy-dense foods and decreasing high-energy-dense foods differently influence weight loss trial outcomes.

BACKGROUND/OBJECTIVE: Although reducing energy density (ED) enhances weight loss, it is unclear whether all dietary strategies that reduce ED are comparable, hindering effective ED guidelines for obesity treatment. This study examined how changes in number of low-energy-dense (LED) (<4.186 kJ/1.0 kcal g-1) and high-energy-dense (HED) (>12.56 kJ/3.0 kcal g-1) foods consumed affected dietary ED and weight loss within an 18-month weight loss trial. METHODS: This secondary analysis examined data from participants randomized to an energy-restricted lifestyle intervention or lifestyle intervention plus limited non-nutrient dense, energy-dense food variety (n=183). Number of daily LED and HED foods consumed was calculated from three, 24-h dietary recalls and anthropometrics were measured at 0, 6 and 18 months. Multivariable-adjusted generalized linear models and repeated-measures mixed linear models examined associations between 6-month changes in number of LED and HED foods and changes in ED, body mass index (BMI), and percent weight loss at 6 and 18 months. RESULTS: Among mostly female (58%), White (92%) participants aged 51.9 years following an energy-restricted diet, increasing number of LED foods or decreasing number of HED foods consumed was associated with 6- and 18-month reductions in ED (ß=-0.25 to -0.38 kJ g-1 (-0.06 to -0.09 kcal g-1), P<0.001). Only increasing number of LED foods consumed was associated with 6- and 18-month reductions in BMI (ß=-0.16 to -0.2 kg m-2, P<0.05) and 6-month reductions in percent weight loss (ß=-0.5%, P<0.05). Participants consuming ⩽2 HED foods per day and ⩾6.6 LED foods per day experienced better weight loss outcomes at 6- and 18-month than participants only consuming ⩽2 HED foods per day. CONCLUSION: Despite similar reductions in ED from reducing number of HED foods or increasing number of LED foods consumed, only increasing number of LED foods related to weight loss. This provides preliminary evidence that methods used to reduce dietary ED may differentially influence weight loss trajectories. Randomized controlled trials are needed to inform ED recommendations for weight loss.