Fat

Utilization | Types | Guidelines | Weight Management | Effects on Endurance

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Utilization

  • Energy
  • Body structure
  • Cell membranes
  • Protection
  • Essential fatty acids
  • Hormones & bile salts
  • Vitamin Carrier (Fat soluble vitamins A, D, E)
  • Palatability & satiety of foods

Types of Dietary Fat

American Dietary Guidelines (2005)

  • A high fat intake (greater than 35% of calories)
    • associated with higher saturated fat intake
      • keep saturated fat below 10% of calories
    • more difficult to avoid consuming excessive calories
  • Low fat intake (less than 20% of calories)
    • increased risk of inadequate intakes of vitamin E and essential fatty acids
    • may contribute to unfavorable changes in HDL and triglycerides

Weight Management

  • Dietary fats are stored and mobilized easily
    • It takes more energy for the body to convert carbohydrates or protein to body fat than it does to convert dietary fat to body fat
  • Typically, less calories are consumed when eating a low fat diet (Lissner 1987, Thomas 1992).
  • A reduction in dietary fat without a reduction in total calories or an increase of physical activity only produces small if any changes in body fat mass (Leibel 1992).

Effects on Endurance

  • High fat diets may limit endurance if carbohydrates are low and body is accustome to a higher carbohydrate diet.
    • A high fat diet may actually increase endurance in certain elite athletes particularly if they have adapted to such a diet
      • Studies are mixed as to whether it increases endurance
      • Ideal would be fat adaptation with high glycogen and intramuscular triglyceride stores
      • Fat adaptation occurs after five days of being on the high fat diet and persists during one day of carbing up (Burke 2000)
    • There is no net glucose synthesis from lipids except from glycerol portion - 10% by weight

 

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