Lean and Obese: Dietary Inflammation

In the Lean and Obese Dietary Inflammation (LODI) study, short-term intake of a high-fat diet (HFD) that is also high in saturated fatty acids will be examined compared to a low-fat diet (LFD) in individuals who are normal body weight (BMI 19.5-24.9) or who have obesity (BMI of 30 - 40 kg/m2). To characterize persons at baseline, this study will examine body composition, and serum glucose, endotoxin, inflammation and intestinal permeability during fasting and in response to a mixed meal. Also, while it is known that long term intake of foods affects the microbiota, it is unclear whether short-term consumption of a HFD will shift towards a pro-inflammatory gut microbiota compared to a low fat intake. This will be tested in a cross-over design (5 days on a HFD, washout, and 5 days on a LFD) with order randomly assigned in older adults (50+ years of age) who have obesity or are normal weight, and will also be examined by estimated visceral adipose tissue level.

Inclusion criteria

• Men or Women
• Age 50-79 years (only postmenopausal women > 2 years)
• Body mass index (20-25 kg/m2; and 30-40 kg/m2)*

Exclusion criteria

• Diagnosed with, active, or history of liver cirrhosis, chronic or persisting hepatitis
• Diagnosed with, active, or history of cancer
• History of gastrointestinal disease or surgical procedure for weight loss.
• Diagnosed with immune diseases, type 2 diabetes, pancreatitis, or infectious diseases
• Any surgery in the past 6 months
• Currently using or have used antibiotics continuously > 3 days in the past 3 months
• Regular use of medications for that affect the gastrointestinal tract, cholecystitis, urinary tract infection, severe organic diseases including coronary heart disease, myocardial infarction, infectious diseases including pulmonary tuberculosis and AIDS
• Known allergy or intolerance to any ingredients in the dietary intervention program
• Alcohol or illicit drug abuse
• Current Smoker or have quit smoking in the past 3 months
• Recent colonoscopy (within the previous two months)
• Inability to follow any of the experimental diets (including low or high fat diet) or to perform the collections required for this study
• Participants will also be excluded if they have extreme dietary habits, extreme levels of physical or athletic activity, or by changes in body weight >5 lbs. during the last 6 months
• Uncontrolled hypertension or uncontrolled hyperlipidemia in abnormal ranges.
• Participation in another clinical research trial that may interfere with the results of this study.

• As needed, BMI (kg/m2) will be adjusted accordingly for Asian lean and obese definitions