The purpose of this study is to determine whether exercise training leads to changes in the white adipose tissue that are beneficial to the body's regulation of sugar and body weight.

The prevalence of obesity and type 2 diabetes in the United States and worldwide has risen dramatically over the last few decades, resulting in an enormous need for new therapies to treat these conditions. The discovery that beiging of subcutaneous white adipose tissue may increase energy expenditure has led to tremendous interest in beige cells as a potential treatment for diabetes and obesity. An established treatment for type 2 diabetes and obesity is endurance exercise training. Exercise training can improve systemic homeostasis, and although adaptations to skeletal muscle play a critical role in these effects, the underlying mechanisms are not fully understood. Moreover, the contributions of other tissues in these beneficial effects of exercise on metabolism have not been intensively investigated. The study team hypothesizes that exercise training results in fundamental changes to white adipose tissue, including beiging, and these adaptations play an important role in the effects of exercise training to improve metabolic homeostasis.

Inclusion Criteria:

• Age: 25-55 years old at the time of screening

• Body mass index (BMI) must be:

  • ≥20 and ≤ 27 kg/m2 for lean subjects
  • ≥25 and ≤ 37 kg/m2 for subjects with type 2 diabetes
  • ≥27 and ≤ 37 kg/m2 for obese/overweight subjects

• HbA1c values:

  • ≤5.7 ± 0.1% for lean and overweight/obese subjects
  • 6.5 ± 0.1% - 9.0 ± 0.1% for subjects with type 2 diabetes

Exclusion Criteria:

• Age <25 and >55 years old
• Type 1 Diabetes
• HbA1c ≥ 9.0%
• Heart or lung disease
• Basal-Bolus Insulin regimen
• Use of beta-blockers or thiazolidinediones
• Acute systemic infection accompanied by fever, body aches, or swollen lymph glands
• BMI ≥ 37 kg/m2
• Current dieting or weight loss efforts
• Current pregnant or breastfeeding
• Known history of HIV/AIDS or certain cancers
• Biochemical evidence of renal or hepatic dysfunction; renal or liver disease
• Demyelinating diseases such as multiple sclerosis or amyotrophic lateral sclerosis
• Recent blood donation
• Clinical history of stroke
• Severe hypertension (systolic > 160 mmHg or diastolic > 90 mmHg)
• Inability to exercise at 50% of predicted heart rate (HR) reserve at baseline
• Participants who screen positive for The American Heart Association's contraindications to exercise testing
• History of keloid formation

Groups included sedentary adults aged 25-55: lean, overweight/obese without T2DM, and overweight/obese with T2DM. Equal numbers of males and females were enrolled where possible. Participants who did not complete baseline assessments were excluded.

16 weeks