CHOICE OF AND RESPONSE TO DIETARY FAT

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: SPECIAL GRANT
• Reporting Frequency: Annual
• Accession No.: 0218954
• Grant No.: 2009-34323-19892
• Proposal No.: 2009-04205
• Project Start Date: Sep 1, 2009
• Project End Date: Aug 31, 2010
• Grant Year: 2009
• Program Code: [GB]- Human Nutrition, LA

Recipient Organization
LOUISIANA STATE UNIVERSITY
202 HIMES HALL
BATON ROUGE,LA 70803-0100

Performing Department
Administration

Non Technical Summary
Obesity is a major public health concern and residents of Louisiana are among the fattest in the nation. Previous research has linked a high fat diet to weight gain and obesity. An adjustment to the acute exposure to high fat diet is not abrupt and takes time. It has been shown that a high level of physical activity can accelerate the adaptation to a high fat diet by increasing fat oxidation. In this study we will determine the mechanisms involved in this adjustment. To accomplish this, we will evaluate the effects of high and low fat diets in normal and overweight men and women at both low and high levels of physical activity.

Animal Health Component

20%

Research Effort Categories

Basic

80%

Applied

20%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
702	5010	1010	50%
702	6010	1010	30%
703	6010	1010	20%

Knowledge Area
703 - Nutrition Education and Behavior; 702 - Requirements and Function of Nutrients and Other Food Components;

Subject Of Investigation
6010 - Individuals; 5010 - Food;

Field Of Science
1010 - Nutrition and metabolism;

Keywords

metabolic syndrome

dietary fat

liver fat

fat intake

carbohydrate intake

hepatic lipid

food intake

exercise

obesity

central adiposity

Goals / Objectives
The objectives of this proposal are to understand the mechanisms for oscillations of dietary fat/carbohydrate intake that occur over an interval of 3-4 days and to understand how variations of fat intake affect insulin resistance and liver fat. To test these hypotheses we will undertake two specific aims: OBJECTIVE 1: To examine spontaneous oscillations of fat/ carbohydrate intake in relation to energy intake. We hypothesize that changes in leptin may precede the phasing of oscillations of fat intake. OBJECTIVE 2. To test the effects of varying fat intake in the presence of different carbohydrates on the development of insulin resistance and the quantity of liver and muscle fat. We hypothesize that higher dietary fat when eaten with fructose as compared to glucose will exaggerate the insulin resistance and increase the amount of hepatic lipid as measured by magnetic resonance spectroscopy.

Project Methods
Methods for Objective 1: We will recruit 28 dietitians and senior level or graduate level dietetics students to participate in this study because they are more skilled in identifying and accurately recording foods and as we have shown in a previous study. When food intake was measured over a 7 day period the dietitians recorded the energy value of their food to within 6% from the energy expenditure recorded from doubly-labeled water. After each subject receives a thorough explanation of the study, she/he will sign an informed consent and then be instructed in how to obtain a weighed food intake record in order to standardize this across all volunteers. Once the dietary assessment staff are satisfied that food records will be accurately recorded, each dietitian will have a physical examination and baseline laboratory measurements and determination of body fat by DXA and visceral fat by computed tomography. Two samples of blood will be drawn on separate days for baseline leptin in order to reduce issues of regression to the mean. Participants will then receive an accelerometer and be instructed in its use. Each participant will receive a dietary journal to record their food for each of the 17 days of the study. They will be instructed on when to return for blood measurements and body weights. They will be instructed not to change their level of exercise. On the 17th day of the study the final blood will be drawn and body fat will be measured again. Methods for Objective 2: This study is designed to test the hypothesis that the effect of dietary fat on insulin resistance and liver fat will be enhanced when some of the glucose in the high fat diet is replaced with fructose. Both men and women will be recruited. They will be between a BMI of 25 and 35 kg/m2. Subjects will also have at least one other abnormal value for the Metabolic Syndrome using the criteria developed by Adult Treatment Panel III of the NHLBI (21). These criteria include impaired fasting glucose, increased triglycerides or increased blood pressure. After enrollment and signing a consent form approved by the Institutional Review Board they will begin a 7 day diet with 40% fat of which 12% will be saturated fat 45% carbohydrate and 15% protein. At the end of 7 days blood will be collected for baseline measures including lipoprotein pattern (light fluffy LDL=Pattern A; heavy dense LDL=Pattern B). At the end of the 7 day baseline diet, groups of 15 subjects will be randomized in groups of 5 to eat one 3 diets: 1) 20 % fat, 65% carbohydrate 15% protein; 2) 40% fat, 45% carbohydrate (with 20% glucose), 15% protein; 3) 40% fat, 45% carbohydrate (with 20% fructose) 15% protein. Subjects will consume the diets for 2 weeks with one meal per day eaten at the PBRC 5 days a week and the other meals packaged for take-out. Weekend meals will be packaged for take out. At the end of 14 days they will be re-evaluated for the measures that were done at baseline.

Progress 09/01/09 to 08/31/10

Outputs
(N/A)

Impacts
The impact of scientific work takes some time to reverberate through the scientific and policy circles. As we will note below there are a number of implications in this overfeeding study about the quality and quantity of foods that the USDA and DHHS should consider in their food programs. Change in Knowledge, actions, or conditions: The overfeeding project has generated sufficient data to provide the basis for t least 5 publications. One of these has been submitted, two others are nearing completion and the other two are being prepared. Other papers reported below were conducted or related to the themes of this study.

Publications

• de Jonge Lm G.A. Bray GA, Xie H, Rood J, Brock C, Smith SR. 2010. Pennington Biomedical Research Center, LSU, Baton Rouge, LA. Comparison of Energy Expenditure during 8 weeks of overfeeding with 5%, 15% or 25% protein diets. Obes Rev 2010 (Abs).
• Harsha DW, Bray GA. Diet and Blood pressure. The high and low of it. 2010 IN: Nutrition Guide for Physicians. Wilson T., Temple, N.J. Bray G.A. and, Struble M.B. (eds), New York: Humana Press, pp 311-317.
• Malik VS, Popkin BM, Bray GA, Despres J-P, Hu FB. 2010. Sugar sweetened beverages, obesity, type 2 diabetes and cardiovascular disease risk Circulation 121;1356-1364.
• Bray, GA. Soft Drink Consumption and Obesity: It's all About Fructose. 2010 Curr Opin Lipidology 21: 51-57.
• Bray GA, Xie H, de Jonge L, Rood J, Brock C, Smith SR. 2010. Effect of on Insulin Sensitivity to Overfeeding for Eight Weeks Three Different Protein Diets Protein Diets. Intern J Obes 2010 (Abs).
• Smith SR, de Jonge L, Xie H, Rood J, Brock C, Bray GA. 2010, Effect on Body Fat of Eight Weeks of Overfeeding with Three Different Protein Diets. Intern J Obes 2010 (Abs).
• Arguin H, Sanchez M, Bray GA, Lovejoy JC, Peters JC, Jandacek RJ, Chaput JP, Tremblay A. Impact of adopting a vegan diet or an olestra supplementation on plasma organochlorine concentrations: results from two pilot studies. 2010 Br J Nutr. 103(10):1433-41.
• Malik V., G.A. Bray, B.M. Popkin, J.P. Despres, F.B. Hu. Sugar Sweetened Beverages and Risk of Metabolic Syndrome and Type 2 Diabetes: A Meta-Analysis. Diab Care 2010;in press.
• Galgani, J.E., L. de Jonge, M. M. Most, G.A. Bray, S.R. Smith. 2010 Effect of a 3-day high-fat feeding period on carbohydrate balance and ad-libitum energy intake in humans. Intern J Obes 34:886-891.
• Champagne CM, Bray GA. Nutritional Status: An overview of methods of assessment. 2010 IN: Nutrition Guide for Physicians. Wilson T., Temple, N.J. Bray G.A. and, Struble M.B. (eds), New York: Humana Press, pp 227-239.
• Bray, GA, Champagne CM. Obesity: Understanding and achieving a healthy weight. 2010 IN: Nutrition Guide for Physicians. Wilson T., Temple, N.J. Bray G.A. and, Struble M.B. (eds), New York: Humana Press, pp 253-274.