chapter  24
Dietary Fats and Obesity
Pages 32

I. Introduction .......................................................................................................................... 601 II. Dietary Fat and Body Weight.............................................................................................. 602 III. Dietary Fat and Food Intake ................................................................................................ 602

A. Does Dietary Fat Affect Food Intake?......................................................................... 602 B. Mechanisms for Fat-Induced Food Intake ................................................................... 604

1. Caloric Density...................................................................................................... 604 2. Stomach Distention ............................................................................................... 604 3. Metabolic Signals .................................................................................................. 605 4. Effects of Hormones and Pharmacological Agents .............................................. 606

IV. Dietary Fat and Metabolism ................................................................................................ 607 A. Influence of Dietary Fat on Lipogenesis ..................................................................... 607 B. Influence of Dietary Fat on Lipid Uptake.................................................................... 608 C. Influence of Dietary Fat on Fatty Acid Oxidation and Energy Expenditure .............. 609 D. Influence of Dietary Fat on Adipose Tissue Lipolysis................................................ 610

1. Level of Dietary Fat .............................................................................................. 610 2. Type of Dietary Fat ............................................................................................... 611 3. Relationship to Obesity ......................................................................................... 612

E. Influence of Dietary Fat on Insulin Action .................................................................. 612 1. Level of Dietary Fat .............................................................................................. 612 2. Type of Dietary Fat ............................................................................................... 613 3. Reversibility of Diet-Induced Alterations in Insulin Action................................. 614

V. Dietary Fat and Adipose Tissue Cellularity ........................................................................ 614 A. Level of Dietary Fat..................................................................................................... 615 B. Type of Dietary Fat...................................................................................................... 615 C. Interrelationship between Changes in Fat Cell Size and Number............................... 616 D. Cellularity Changes: Reversibility of Obesity and Insulin Resistance........................ 617

References ..................................................................................................................................... 617

Obesity is variably defined as having a body weight of more than 20% over ideal body weight or a bodymass index (weight (kg)=height (m)2) of 30 or more [1]. Obesity is associated with many chronic diseases and alterations in physiological function, including cardiovascular disease, hypertension, diabetes mellitus, gallbladder disease, and certain types of cancer [2]. Obesity is a major public health problem in the United States and Europe and is becoming increasingly important in many other areas of the world [3]. The prevalence of obesity in adults in the United States has increased by 30% ormore in the past decade, with increases in both genders and in all ethnic and racial populations and age groups [4]. It is now estimated that in the United States more than one-third of the total adult population and one-half of the adult African American and Hispanic population are obese [5].