#9 NST160Macronutrients- revised

#9 NST160Macronutrients- revised - NST 160 Dietary...

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Unformatted text preview: NST 160 Dietary Macronutrients: Consequences of Carbohydrate and Fat Intake Marc K. Hellerstein, M.D., Ph.D. Professor of Human Nutrition (D.H. Calloway Chair), University of California Berkeley; Professor of Endocrinology, Metabolism and Nutrition, Dept. of Medicine, University of California at San Francisco Easier to tell someone what type of food to eat (or not to eat) than how much to eat Changes in diet composition can be induced experimentally and consequences established Differences in diet composition exist among populations, allowing epidemiologic comparisons Changes in diet composition have occurred in the population Magic bullet view of weight lossand complex disease risk is eternally attractive! Why the Interest in Macronutrient Content of Diet? Energy Intake Disordered appetite Impaired satiety or hunger control Sensitivity to external cues Hypothalamic or CNS lesions Hormone deficiencies (insulin, Leptin) Psychological (depression, stress) Dietary factors Energy-dense, low-satiety foods High-fat diets ? Binge eating, irregular meals ? Food insecurity (fear of deprivation) Energy expenditure Reduced TEE Low REE (genetic) Low lean body mass (active tissue) Low SNS activity Hormone deficiencies (T3, Leptin) Sedentary lifestyle Weight loss (below usual body weight) Low fidgeting (involuntary activity) Impaired fat oxidation High insulin sensitivity 1 tissue fuel selection (malonyl-CoA) Inadequate fatty acid mobilization Overactive adipose lipoprotein lipase Surplus dietary carbohydrate High endogenous glucose production Nutrient Partitioning Impaired LBM formation Lack of muscle contraction Genetic factors Dietary protein inadequacy Sex steroid hormone deficiency (hypogonadism) Glucocorticoid excess Other hormones (T3, Leptin, 3, insulin, IGF-1) Altered adipocyte metabolism High fat cell number (differentiation or proliferation) High lipogenesis Hormone effects (insulin, GH, catechols) Body fat stores How Can Diet Influence Energy Balance/Obesity? Review of Basic Principles Macronutrient economies: are fats and carbohydrates (CHO) independent systems? Lack of conversion of fats to CHOs in animals (biochemical reasons why) Role of de novo lipogenesis (DNL,conversion of CHO to fat) in humans? Different than some other animals (e.g., pigs, cows, bees) Energy cost of DNL/FA oxidation pathway Is a calorie a calorie? i.e., Can you get fat Is a calorie a calorie?...
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#9 NST160Macronutrients- revised - NST 160 Dietary...

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