Alteration of dietary fat intake to prevent weight gain: Jayhawk Observed Eating Trial.
OBJECTIVE
To examine the effects of ad libitum diets with three distinct levels of fat intake for the prevention of weight gain in sedentary, normal-weight and overweight men and women.


METHODS
Three hundred and five participants were randomized to one of three diets. The diets targeted <25% of energy from fat (low fat (LF)), between 28 and 32% of energy from fat (moderate fat (MF)), or >35% of energy from fat (high fat (HF)). Participants consumed two meals per day on weekdays and one meal per day on weekends in a university cafeteria over a 12-week period. Energy and nutrient content of cafeteria foods were measured by digital photography. All meals and snacks consumed outside the cafeteria were measured by dietary recall. All analysis of energy and nutrient content was completed using Nutrition Data System for Research (NDS-R) version 2005.


RESULTS
Two hundred and sixty participants completed the study. LF gained 0.1 +/- 3.1 kg, MF gained 0.8 +/- 2.5 kg, and HF gained 1.0 +/- 2.2 kg and there was no gender or age effect. Longitudinal mixed modeling indicated a significant difference among the groups in weight over time (P = 0.0366). When adjusting for total energy intake, which was a significant predictor of weight over time, the global effect for the group was eliminated. Thus, increasing weight was a function of increasing energy but not increasing percentage of fat intake.


CONCLUSIONS
Energy intake, but not percentage of energy from fat, appears responsible for the observed weight gain. LF diets may contribute to weight maintenance and HF diets may promote weight gain due to the influence of fat intake on total energy intake.
Donnelly
Joseph E
JE
Energy Balance Laboratory and Center for Physical Activity, Nutrition, and Weight Management, Schiefelbusch Institute for Lifespan Studies, University of Kansas, Lawrence, Kansas, USA. Jdonnelly@ku.edu
Sullivan
Debra K
DK
Smith
Bryan K
BK
Jacobsen
Dennis J
DJ
Washburn
Richard A
RA
Johnson
Susan L
SL
Hill
James O
JO
Mayo
Matthew S
MS
Spaeth
Kendra R
KR
Gibson
Cheryl
C
D000293:Adolescent; D000328:Adult; D015992:Body Mass Index; D018752:Diet, Fat-Restricted / Q000379:methods*; D004041:Dietary Fats / Q000494:pharmacology*; D004435:Eating / Q000187:drug effects / Q000502:physiology; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D007615:Kansas; D008297:Male; D009043:Motor Activity / Q000502:physiology; D009765:Obesity / Q000178:diet therapy / Q000517:prevention & control*; D010349:Patient Compliance; D012528:Satiety Response / Q000187:drug effects / Q000502:physiology; D014495:Universities; D015430:Weight Gain / Q000502:physiology*; D015431:Weight Loss / Q000187:drug effects / Q000502:physiology
D004041:Dietary Fats