Difficulty recruiting participants that met the inclusion criteria

Obesity is associated with a constellation of cardiometabolic abnormalities (including insulin resistance, elevated blood pressure and dyslipidemia) that are risk factors for diabetes and cardiovascular disease. Weight loss can improve all of the cardiometabolic abnormalities associated with obesity. Up to ~25% of lean people (Body Mass Index [BMI] 18.5-24.9 kg/m²) have many of the cardiometabolic abnormalities associated with obesity and are referred to as metabolically abnormal lean (MAL) people. However, the MAL phenotype is not well characterized, and it is unclear whether weight loss has beneficial metabolic effects in already lean people. Accordingly, the goal of this study is to: 1) carefully phenotype MAL people and 2) evaluate the effect of moderate (8-10%) diet-induced weight loss in MAL people. This will be investigated in 15 MAL (defined as having 2 or more of the following: intrahepatic triglyceride (IHTG) content ≥5.6%, glycated hemoglobin ≥5.7%, fasting plasma glucose concentration ≥100 mg/dl, 2-hr oral glucose tolerance test (OGTT) plasma glucose concentration ≥140 mg/dl, homeostatic model assessment of insulin resistance (HOMA-IR) ≥ 2.5) men and women. Only lean people who have a BMI ≥21.0 but <25.0 kg/m² will be asked to lose weight to avoid the risk that participants become underweight (BMI <18.5 kg/m²) during weight loss therapy.

Inclusion Criteria:

• BMI 21.0-24.9 kg/m²
• Weight stable (+/- 2% for at least 3 months before enrollment)
• Two or more of the following: IHTG content ≥5.6%, HOMA- IR index ≥ 2.5, HbA1C ≥ 5.7%, 2-hr OGTT plasma glucose concentration ≥ 140 mg/dl, fasting plasma glucose concentration ≥ 100 mg/dl.

Exclusion Criteria:

• Women who are pregnant or breastfeeding
• Evidence of significant organ system dysfunction or disease (e.g., diabetes, chronic kidney disease, advanced heart disease, etc.)
• Men who consume >21 units (e.g., glass of wine or bottle of beer) of alcohol per week and women who consume >14 units of alcohol per week
• Use of dietary supplements or medications known to affect metabolism
• Eating disorder (assessed by using the Eating Disorder Examination Questionnaire [EDE-Q])
• Participation in structured endurance or resistance exercise program >150 min/week
• Use of tobacco products
• Unable or unwilling to follow the study protocol or the research team believes that for any reason the volunteer is not an appropriate candidate for this study, including non-compliance with screening appointments or previous appointments/contact arrangements
• Individuals that take Coumadin or similar anticoagulants
• Use of antibiotics in last 60 days
• Previous bariatric surgery
• Cancer or cancer that has been in remission for <5 years
• Major psychiatric illness