Effect of Ultra Processed Versus Unprocessed Diets on Energy Intake

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

Overconsumption of foods that result from extensive industrial processing is believed to contribute to the development of obesity. Ultra-processed foods now represent most of the calories consumed in America and their contribution to overall diet has increased in parallel with the rise in the prevalence of obesity over the past several decades. While such correlations are suggestive, the effect of industrial processing per se, independent of dietary macronutrient composition, on ad libitum energy intake has not been carefully investigated. Therefore, we will conduct feeding studies in adult men and women to investigate the differences in ad libitum energy intake resulting from consuming test diets for a pair of 2-week periods in a randomized, crossover design during a single 4-week period. The test diets presented to participants will be matched for calories, macronutrient composition, sugar, fiber, and sodium, but one diet will be composed of ultra-processed foods whereas the other diet will be unprocessed foods.

Eligibility Criteria:
* INCLUSION CRITERIA:

  1. Adults age 18-50 years, male and female
  2. Weight stable (\< +/- 5 % over past 6 months)

  4. Body mass index (BMI) greater than or equal to 18 kg/m\^2

  5. Willing to cease their habitual caffeine intake during the study, beginning one week prior to inpatient admission

  6. Written informed consent

  7. Willing to eat the food provided in the study

  8. Able to complete daily bouts of stationary cycling at a moderate rate and intensity with a heart rate (HR) equal to or greater than 0.3x(220-age-HR(rest))+HR(rest) but not exceeding 0.4x(220-age-HR(rest))+HR(rest) and no signs of arrhythmia

EXCLUSION CRITERIA:

1. Evidence of metabolic or cardiovascular disease, or disease that may influence metabolism (e.g. cancer, diabetes, thyroid disease)
2. Taking any prescription medication or other drug that may influence metabolism (e.g. diet/weight-loss medication, asthma medication, blood pressure medication, psychiatric medications, corticosteroids, or other medications at the discretion of the PI and/or study team)
3. Hematocrit \< 34% (women only)
4. Hematocrit \< 40% (men only)
5. Pregnancy, lactation (women only)
6. Participating in a regular exercise program (\> 2h/week of vigorous activity)
7. Caffeine consumption \> 300 mg/day
8. Regular use of alcohol (\> 2 drinks per day), tobacco (smoking or chewing) amphetamines, cocaine, heroin, or marijuana over past 6 months
9. Eating disorders or psychological conditions, such as (but not limited to) claustrophobia, clinical depression, bi-polar disorders, that would be incompatible with safe and successful participation in this study, as determined by investigators.

   --Past or present history of claustrophobia since part of the protocol will involve being confined to a small room for whole-body indirect calorimetry and being in an MRI scanner for liver fat measures
10. Implants, devices, or foreign objects implanted in the body that interfere with the Magnetic Resonance procedures
11. Volunteers with strict dietary concerns (e.g. vegetarian or kosher diet, food allergies)
12. Volunteers unwilling or unable to give informed consent
13. Non-English speakers due to unavailability of required questionnaires in other languages.