Effect of Ultra Processed Versus Unprocessed Diets on Energy Intake

Detailed Summary

Background: Eating too much processed food is believed to lead to obesity. But the effect of processed food on energy intake has not been carefully studied. Researchers want to study people s diets for 4 weeks and do specialized tests of the effects. Participants will get two diets. They will have the same calories and nutrients, but one diet will be unprocessed food and the other will be ultra-processed. Objective: To better understand how processed and unprocessed foods affect daily food consumption and how the body handles blood sugar. Eligibility: Healthy adults ages 18-50 who have stable weight and can exercise Design: Participants will not eat for 12 hours. Then they will be screened with: * Medical history * Physical exam * Heart and blood tests * Resting energy expenditure test (REE). A hood will collect air exhaled while lying down for 30-40 minutes. * Psychiatric questions * Questions about mood, eating, sleep, and socioeconomic status * 20-minute stationary biking Female participants will have a urine pregnancy test. Participants will stay in the clinic for 4 weeks. For 2 weeks they will get a processed diet. For the other 2 weeks they will get an unprocessed diet. Participants cannot use the study period to gain or lose weight. Participants will have: * Meals and snacks provided * Daily exercise * Blood, urine, and saliva tests * To drink a special water and a very sweet liquid * REE * Scans and X-rays * To wear activity monitors and a device to measure blood sugar * Several 24-hour periods in a room that measures oxygen and carbon dioxide * Repeats of screening questions * Questions about hunger and meals * Sleep monitoring * Taste tests

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Interventions