Zone diet

 

Zone explained

  • Zone is set of exercise and eating habits that balance insulin and eicosannoids: 30% fat, 30% protein, 40% low glycemic carbohydrate
    • Being out of zone with high glycemic foods leads to decreased lean mass production and decreased fat burn
    • Protein sources should be bioavailable (ie meat and dairy derived and non-vegetable) and entry of aminos to blood should be controlled in order to control hormonal effects they may induce by combining effectively with fat and carbohydrate
      • Protein requirements determined by weight, % body fat and level of physical activity
    • Bad fats are those that are substrates for inflammatory eicosanoids such as egg yolks, organ meats and fatty meats
      • Saturated fats in animal protein and dairy products linked to insulin resistance
      • Monounsaturated fats are not used in eicosanoid production, increase feeling of fullness due to Cholecystokinin (CKK) stimulated release by presence of fat in stomach and slower carbohydrate absorption to blood
      • Slower carbohydrate absorption to blood leads to less stored fat, increased usage of fat and faster transition to burning fat

Eicosanoids

  • Eicosanoid type produced determined by dietary intake of fat, insulin and stress
    • Delta 6 desaturase enzyme that converts Linoleic Acid depressed by ALA, Trans fats, Viral infections and Adrenalin leading to decreased anti-inflammatory eicosanoid production
    • Delta 5 desaturase enzyme that converts next stage in process inhibited from producing anti-inflammatory eicosanoids by cortisol and insulin which promote inflammatory eicosanoid production
    • Delta 5 desaturase enzyme production of anti-inflammatory eicosanoids enhanced by Glucagon and EPA
  • Diet high in carbohydrates leads to excess insulin leading to production of inflammatory eicosanoids which in turn exacerbates blood sugar imbalances and leads to increased fat storage

Athletes and High carbohydrate diet

  • High carbohydrate diet leads to
    • Increased insulin and inflammatory eicosanoids leading to reduced oxygen transfer to muscles leading to reduced endurance and reduced physical performance
      • Inflammatory eicosanoids inhibit breakdown of fat for energy production
      • Athlete becomes conditioned to sourcing energy primarily from carbohydrate leading to faster muscle glycogon storage use and decreased endurance
    • Hyperinsulemia resulting from high carbohydrate intake
      • Increases fat production
      • Inhibits fat breakdown: body cannot produce fat and break it down at the same time – body needs time to switch from fat production to fat breakdown
      • Insulin effects on blood glucose storage and decreased fat breakdown leads to hypoglycemia, energy deficit, slowed metabolism and low blood supply to brain
      • Energy deficits lead to glucose cravings
    • Balanced carbohydrate intake leading to
      • Balanced blood sugar for 4 to 6 hours leading to increased mental alertness
      • Increased fat metabolism and more efficient energy metabolism
      • Increased oxygen transfer and decreased muscle fatigue

Exercise

  • Below 60% VO2 max and during low intensity activities, fat breakdown is preferred for energy production
    • If body is conditioned to store fat, enzymes used in energy production will favor carbohydrate for energy production
    • Use of carbohydrate as energy substrate comes habit for enzymes due to normalized circulation of glucose from carbohydrate (through dietary habits that sustain high blood sugar through diet high in high glycemic foods) as well as conditioned ability for enzymes to break down carbohydrate by preference and ease for fast energy yield
  • At 60% to 80% VO2 max and during high intensity aerobic exercise
    • Insulin levels are reduced and glucagon levels are increased and body becomes conditioned to using carbohydrates directly (thus maintaining insulin sensitivity) and not storing them as fat
    • The balance of eicosanoid production favors anti-inflammatory eicosannoids that promote
      • Release of fat from adipose tissue
      • Dilated blood vessels leading to increased oxygen transfer
      • With increased oxygen metabolism, aerobic capacity and endurance is enhanced
    • At 90% of VO2 max and during anaerobic exercise
      • Muscle microdamage and breakdown occurs leading to release of Human Growth Hormone (HGH)
      • HGH requires a lot of energy which is sourced from fat
      • HGH promotes fat burning and production of lean body mass
      • HGH released during REM sleep
        • Carb snack leads to increased insulin which inhibits HGH release
        • Lack of HGH release during sleep leads to lack of restful sleep and proper anabolic body repair: body in catabolic state

Criticism of unbalanced Diets

Diet high in Protein:

  • Lead to ketosis when carbohydrate stores are used up and body metabolizes fat (takes less than 24 hrs). Leads to ketone production which body tries to expel through urination, leading to water loss
  • Ketogenic diet leads to excess insulin to curb amino circulation, leading to insulin converting protein to fat (hmm … true?)
  • Ketogenic diet causes fat cells to become more efficient at storage leading to yo-yo weight loss and gain
  • Ketogenic diet as causing muscle catabolism to sustain glucose supply to brain

Sourced from:

Sears, B. (1995). The Zone Diet: A Dietary Road Map. New York, NY: Harper Collins

 

 

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