Is Strength Training a Viable Exercise Modality for Fat Loss?
Condition: Overweight and Obesity
MeSH terms: Overweight
Study type: Interventional

Summary: 
      The purpose of this study is to determine whether strength training can be used as a viable
      exercise modality for the purpose of inducing fat loss.
    

Detailed description: 
      Aerobic exercise (AE) is commonly recommended as the most effective exercise modality for
      weight loss. The Centers for Disease Control (CDC) recommends 150 minutes of AE for weight
      maintenance, and an unspecified greater amount required for weight loss. Similarly, the
      American College of Sports Medicine (ACSM) position stand on physical activity for weight
      loss recommends 150-250 minutes per week of moderate intensity physical activity. While the
      ACSM promotes resistance training (RT) as a means of increasing fat free mass, which should
      lead to improved body composition, it does not promote RT for losing significant amounts of
      body fat. Similarly, the CDC physical activity guidelines for weight loss do not mention RT
      at all as a viable exercise modality for weight loss. This is not surprising, as there is a
      paucity of research examining the effects of RT on weight loss. Furthermore, the few studies
      that have explored RT for weight loss generally show that it is ineffective. The
      effectiveness of any weight loss program is dependent on the size of the caloric deficit that
      is created over time, and since AE generally burns more calories per unit of time than RT, it
      stands to reason that AE would be the most commonly prescribed type of exercise for weight
      loss. Contributing to the exclusion of RT for weight loss is a widespread belief among
      dietitians, nutritionists and exercise professionals that it is not possible to induce muscle
      growth while in a caloric deficit, and since the creation of a caloric deficit is essential
      for fat loss, the use of RT for muscle growth in a caloric deficit is counter intuitive.

      However, RT has been shown to elevate resting metabolism for an extended period of time
      following cessation of the training session. Additionally, having a greater muscle mass
      should lead to a greater resting metabolism. Unlike RT, chronic AE performed in a caloric
      deficit (which is often the recommendation for effective weight loss) has the potential to
      lead to significant decreases in muscle mass, thereby hampering improvements in body
      composition. Ideally, a program designed to improve body composition should do so through fat
      losses alone, with muscle mass being maintained or increased.

      Several reasons could exist for the lack of effectiveness of RT shown in most studies. These
      reasons include, but are not limited to, 1) Body mass being the measured outcome and not body
      composition, 2) lack of control and/or measurement of caloric intake, 3) failure to adjust
      dietary protein needs to support muscle growth, 4) ineffective RT program design. Case
      studies of clients from our lab have routinely shown that profound decreases in bodyfat can
      be induced with RT as the exclusive form of exercise. Furthermore, these decreases in bodyfat
      occur with concomitant increases in muscle mass, while in a caloric deficit. Therefore, the
      specific aims of this proposal are:

        1. To determine whether RT combined with dietary intervention (RT+DIET) results in greater
           decreases in fat mass than (RT) or dietary intervention (DIET) alone.

        2. To determine whether RT combined with dietary intervention (RT+DIET) results in greater
           improvements in body composition than (RT) or dietary intervention (DIET) alone.

        3. To determine whether concomitant increases in muscle mass and decreases in fat mass can
           occur while in a caloric deficit.

      The goal of this project is to serve to generate pilot data to determine whether RT can be
      used as a viable exercise mode for fat loss and muscle gain. We will then pursue funding for
      a subsequent study that compares the effects of RT versus AE on body composition and fat loss
      when 1) the caloric intake is monitored to ensure the creation of a caloric deficit, and 2)
      dietary protein is appropriately increased to support muscle retention/growth.
    

Intervention name(s): Diet Only; Training Only; Diet plus Training
Intervention type(s): Behavioral; Behavioral; Behavioral
Intervention description(s): Food tracking based on macronutrient goals.; Subjects completed 16 weeks of supervised resistance training; Food tracking plus resistance training.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: resistance training; metabolism