Effect of Different Types of Carbohydrates Consumed After Exercise on Blood Fat Levels
Condition: Hyperlipidemia
MeSH terms: Hyperlipidemias
Study type: Interventional

Summary: 
      The increase in fat (i.e. triglyceride) in the blood after a meal is a well-established risk
      factor for heart disease (Nordestgaard et al. 2007). Endurance exercise is beneficial for
      improving the blood lipid response to a subsequent meal; that is, the appearance of fat
      (triglyceride) in the blood is less after a meal if endurance exercise was performed shortly
      before (i.e. within half a day) of the meal (Petit et al. 2003). This benefit of exercise is
      unfortunately negated if the after-exercise food choice to replace the calories expended
      during exercise is one containing high glycemic index carbohydrates. For example, if a high
      glycemic index carbohydrate is consumed after an evening exercise session, the exercise no
      longer has an effect of lowering triglyceride in the blood after a meal consumed the next
      morning (Harrison et al. 2009; Burton et al. 2008). Very rarely do people perform an exercise
      session and then fast until their next meal hours later. The more common practice is to
      consume food immediately after the exercise to enhance recovery and because hunger is
      stimulated with exercise. Consuming carbohydrate with a low glycemic index has been shown to
      reduce the level of fat in the blood following a subsequent meal (Gruendel et al. 2007). To
      date, no studies have examined the effects of consuming a low-glycemic index meal after
      exercise on the blood fat response to a subsequent meal. The specific objective of our
      research is to determine the effect of consuming low glycemic index lentils after an
      endurance exercise session on the blood fat (triglyceride) response to a subsequent meal.
      Twenty-five overweight or obese men will have their blood triglycerides measured four times
      over six hours after a high-fat morning meal following four different conditions, in a
      randomized, counterbalanced, cross-over design (i.e. the 25 subjects will each participate in
      all four conditions, where the order of conditions for each person is randomized): 1) After
      exercise (90 minutes of moderate intensity walking) is performed the evening before, followed
      by caloric replacement with a high-glycemic index meal (i.e. white bread and instant mashed
      potatoes); 2) After the same exercise is performed the evening before, followed by caloric
      replacement with a lentil-based meal; 3) After the same exercise is performed the evening
      before, followed by fasting; 4) After a no exercise/ no meal condition (i.e. control
      condition). In addition to measuring blood triglycerides we will measure blood insulin, free
      fatty acid, high density lipoproteins, low density lipoproteins, and glucose levels as these
      are also related to cardiovascular disease risk and may be altered with exercise and lentil
      consumption. We will also measure the muscle's ability to burn fat (i.e. fat oxidation) by
      assessing respiratory gases (oxygen consumption and carbon dioxide output) after the high-fat
      meal because we expect exercise and lentils to increase fat oxidation. Our expected results
      are that consuming lentils after endurance exercise will lower the blood triglyceride
      response to a subsequent meal compared to exercise alone or when high-glycemic index
      carbohydrates are consumed after the exercise.
    


Intervention name(s): Exercise; Diet (meal type)
Intervention type(s): Behavioral; Other
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Basic Science