In the Lean and Obese Dietary Inflammation (LODI) study, the primary goal is to determine the effect of short-term intake of high dietary fat (5 days) compared to low fat intake (5 days) in a cross-over design in older adults (men and women) with normal body weight or obesity. Inflammation will be examined by measuring serum endotoxin and other markers, as well as the fecal microbiota.

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

Individual participant data that underlie the results and after deidentification will be shared upon request for researchers who provide a methodologically sound proposal (and IRB approved).