Acute effects of caloric intake and macronutrient type on body weight, body composition, resting energy expenditure, and total metabolic rate.

Obesity is a growing epidemic with no consensus regarding solutions. Thirty healthy overweight and obese female subjects (41.9 ± 12 years, 166 cm ± 7 cm, a 100.5 kg ± 19.6 kg, 46.0% ± 4.0% body fat, and BMI 37.4 ± 6.9) participated in the study. A 14-day dietary intervention examined acute effects of energy balance and macronutrient type on dietary intake, REE, body weight, body composition, and thyroid panel. Significant changes occurred in weight loss over time (p < 0.001); body fat mass over time (p < 0.001) and time x diet (p = 0.02); body fat percentage over time (p < 0.002) and time x diet (p = 0.023); REE over time (p = 0.03), and thyroid panel. Body weight continued to decrease during positive energy balance, yet metabolism rebounded. Results suggest energy balance has a greater overall effect on REE and weight loss than macronutrient type.