The purpose of this study is to find out how the amount of fat or sugar in a person's diet, or the number of meals eaten each day, affect the amount of fat that people's bodies make, the types of fats in the bloodstream, and how much fat is stored in the liver. The study is funded by the National Institutes of Health.
The study consists of two 10-day feeding periods that are separated by approximately two weeks. During each feeding period all food and beverages to be consumed will be provided by the study. In Study 1, participants will be randomly assigned to receive one of two diets. Both diets are designed to maintain weight at a constant level. The diets are balanced nutritionally and have the same amount of protein. One diet has higher amounts of sugar, while the other has higher amounts of fat. For one 10-day period, the diet will be fed as two large meals ('meal-feeding'). For the other 10-day period, the identical diet will be fed as 8 small meals ('nibbling'). Half of the participants will meal-feed first, while the other half will 'nibble' first. The order of nibbling or meal feeding will be determined randomly. In Study 2, the number of meals eaten per day will remain fixed at three (no nibbling or meal feeding). Participants will receive both the diet higher in sugar and the diet higher in fat. However, they will be randomly assigned to start one followed by the other for each 10-day feeding period. At the end of each 10-day feeding period, participants will spend two nights in a research ward (Clinical Research Center) to undergo testing.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
DOUBLE
Enrollment
48
Weight-maintaining diet relatively high in sugar fed as two large meals daily
Weight-maintaining diet relatively high in sugar fed as 8 meals daily
Weight-maintaining diet relatively high in fat fed as two large meals daily
University of California, San Franciso, San Francisco General Hospital
San Francisco, California, United States
Effect of meal composition on fractional de novo lipogenesis (fatty acid synthesis)
Differences between high carbohydrate and high fat diets on postprandial de novo lipogenesis De novo lipogenesis will be measured using stable (not radioactive) isotopes given intravenously and orally during feeding.
Time frame: After 10-day dietary period
Effect of meal frequency on fractional de novo lipogenesis (fatty acid synthesis)
Differences between consuming the same diet as eight small meals per day or two larger meals per day on postprandial de novo lipogenesis. Please see description of measurement of de novo lipogenesis under aim 1.
Time frame: After 10-day dietary period
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Weight-maintaining diet relatively high in fat fed as 8 small meals daily
Weight-maintaining diet relatively high in sugar fed as 3 meals daily
Weight-maintaining diet relatively high in fat fed as 3 meals daily