Effects of a Calorie Restricted, Very Low Fat Plant-based Diet and Multi-component Exercise Program on Metabolic Health
Condition: Obesity; Insulin Resistance
MeSH terms: Insulin Resistance
Study type: Interventional

Summary: 
      The purpose of this study is to understand how weight loss by a very low fat plant-based diet
      with an exercise program affects metabolic and cardiovascular health in overweight adults at
      high risk for disease. Outcome measures will include assessment of insulin sensitivity,
      β-cell function, body fat distribution, skeletal muscle and adipose tissue biology,
      cardiovascular function, cardiorespiratory fitness, muscular strength, immune function, and
      the gut microbiome.
    

Detailed description: 
      Reduced energy intake and increased physical activity have profound effects on
      cardiometabolic health as assessed by insulin sensitivity, β-cell function, serum lipids,
      intra-abdominal fat mass, intrahepatic triglyceride content, and blood pressure, and is the
      cornerstone of treatment for people with obesity. However, the specific additional
      therapeutic effects of regular exercise in conjunction with diet-induced weight loss are not
      clear. In addition, the optimal dietary macronutrient composition needed to reduce
      cardiometabolic risk is not known. The use of a very low fat, plant-forward diet is becoming
      increasingly popular to treat people with obesity and is the only diet therapy that is
      reimbursed by Medicare in the treatment of people with coronary heart disease.

      Participants will undergo nutritional counseling and have supervised exercise training 4 days
      per week plus unsupervised exercise sessions performed 2 days per week until 7-10% weight
      loss is achieved. Meals will be provided and food diaries will be kept during weight loss.
      Tests before and after the intervention will include muscular strength and aerobic fitness,
      cardiovascular assessments, glucose tolerance tests, hyperinsulinemic euglycemic clamp test
      for insulin sensitivity, muscle biopsies, body composition scans, blood tests, and urine and
      stool collections.

      The overarching goal of this project is to conduct a comprehensive characterization of weight
      loss induced by using a PB diet with regular exercise in people with obesity, prediabetes and
      insulin resistance, followed by a comparison of the effects of this study with those from
      another study that is evaluating the effect of the same amount of weight loss induced by
      using a PB diet alone, without exercise. Specifically, we will evaluate changes in body
      composition, body fat distribution, cardiopulmonary function, muscle strength, the plasma
      proteome, insulin sensitivity, beta-cell function, systemic inflammation, muscle cellular
      metabolic pathways, and the gut microbiome to determine cellular, multiorgan, and whole-body
      effects of PB diet alone and PB diet plus exercise. Accordingly, this study will fill two
      important gaps in our knowledge that have considerable physiological and clinical
      significance; the data from this study will provide: 1) a better understanding of the effects
      of calorie restriction-induced weight loss plus exercise on a series of key outcome measures,
      and 2) the potential additional benefit of adding regular exercise to a plant-forward diet.
    

Intervention name(s): Weight loss with very low fat plant-based diet and regular exercise
Intervention type(s): Other
Intervention description(s): Participants will lose ~7-10% of their body weight while on a calorie-restricted very low fat plant-based (PB) diet and performing exercise 6 days/week (4 sessions/week under direct supervision). The macronutrient composition of the diet is approximately 70% of energy from carbohydrate, 15% from protein, and 15% from fat. Food will be provided in the form of take-out meals and will be picked up by participants during weekly study visits with a weight management dietitian. To promote adherence to the diet and exercise intervention, subjects will participate in a lifestyle intervention program that includes dietary and behavioral education topics. Treatment will be provided in weekly individual or group sessions depending on subject availability. (Note: this is the only intervention for the study; the hyperinsulinemic euglycemic clamp is not an intervention but is the gold standard for evaluating insulin sensitivity, a primary study outcome.)
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Other