Progress 09/01/10 to 08/31/12
Outputs
OUTPUTS: The objective of these projects is to understand how humans respond to a positive energy balance produced by two strategies. Outputs have been limited due to the preliminary data in this work. Several presentations have incorporated the results of this work. PARTICIPANTS: George Bray, MD, (PI), Corby K. Martin, Marc Hamilton, Catherine Champagne, Pennington Biomedical Center, LA. TARGET AUDIENCES: The scientific community interested in the effect of excess energy intake and whether different methods for achieving this have different responses from the individual. PROJECT MODIFICATIONS: Both project 1 and 2 were designed as larger studies which would have taken 3-4 years to complete. When funding was withdrawn they were reshaped to complete as much work as possible within the limits of the available research funds. The results obtained so far should provide a tantalizing look at what might have been available if the projects has been completed as originally planned.
Impacts
Project 1 examined the metabolic and behavioral effects of a two-day positive energy balance which was induced by increasing food intake 140% above baseline energy requirements and keeping energy expenditure constant. Three diets varied in dietary fat and energy density (kcal/g): 1) A high fat/high energy dense diet (HF/HED with 15% protein, 50% fat, 35% carbohydrate (carb), and 1.58 kcal/g); 2) high fat/low energy dense diet (HF/LED; 15% protein, 50% fat, 35% carb, and 1.09 kcal/g), and 3) high carb/low energy dense diet (HC/LED; 15% protein, 20% fat, 65% carbohydrate, and 1.02 kcal/g). Ad libitum energy intake (EI) was not suppressed until the second day after overeating and reductions in EI accounted for only ~30% of the excess energy ingested. Reduction in EI did not differ among the three diets over four days, although EI did decrease significantly after the high fat/low energy dense (HF/LED) diet when EI from days 2-4 were analyzed. Overeating had no effect on subsequent energy expenditure but after both of the low energy dense diets sleep time was decreased compared to the HF/HED. The HF/LED was associated with decreased carbohydrate cravings, hunger, prospective food consumption, and food satisfaction compared to the HF/HED. The HF/LED led to greater feelings of happiness, relaxation, and tranquility compared to a HF/HED. A delay in compensation after short-term overeating occurs, and that the diet type had no impact on compensation on days 1-4, even though EI decreased from baseline after the HF/LED on days 2-4. Project 2 examined the acute Metabolic effect of physical inactivity (the "oversitting" study). A counterbalanced cross-over study compared the metabolic responses when food intake was held constant and a positive energy balance induced by reducing physical activity. Participants ingested 3 standardized meals, and performed supervised sitting/sleeping/standing and walking while residing on the metabolic unit. Metabolic responses were assessed from a continuous glucose monitor system with periodic blood sampling. Healthy adults aged 24-52 yrs with a body mass index 22-36 kg/m2 had a VO2max testing indicated low-moderate fitness with a maximal aerobic capacity 20-44 ml/min/kg. There was a 0.47 kcal/kg/hr difference in energy expenditure between the inactive and active trials. This magnitude of difference was insufficient to alter consistently the rise in glucose during the postprandial period. Plasma insulin concentrations increased significantly more in the 30-240 min after eating breakfast when inactive, and this was reflected in a greater area under the curve for plasma insulin concentration. Sitting too much can directly cause insulin resistance during acute periods after eating. This work has important implications for food policy and public health.
Publications
- No publications reported this period
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