21 CONTENTS 2.1 INTRODUCTION David A. Levitsky The Control of Food Intake and the Regulation of Body Weight in Humans 2 2.1 Introduction 21 2.1.1 Classic Argument for the RegulatioR of Body Weight through the Control of Food Intake 22 2.1.1.1 Constancy of Body Weight... 22 2.1.1.2 Response to Food Deprivation 23 2.1.1.3 Response to Overfeeding 24 2.1.2 Response to Energy Density ofthe Diet.. ·· .. ·· .. ···· 25 2.2 Opportunity Not Regulation 26 2.3 Evidence of the Nonregulation of Human Feeding Behavior. · 29 2.3.1 Portion Size Effect · ·.. ·· ·.. · ··· ·· 29 2.3.2 Variety Effect. · ·.. ·· .. · ·· .. · ·30 2.3.3 Social Effect 32 2.4 Stimulus-Bound Eating: An Alternative to Regulation Theory 33 2.5 A Possible Solution: Regulation through Cognition 34 References 35 A common belief among the vast majority of researchers and practitioners involved in the control of food intake of humans is that body weight is regulated through the control of food intake. Implicit in this belief are two assumptions: (1) body weight is physiologically regulated, and (2) it is regulated specifically through the control of energy intake. These assumptions originate deep in the history of animal physiology and psychology and have been seldom questioned. Yet the veracity of these assump- tions will determine the success of our efforts to stem the surge of overweight and obesity so evident throughout the world.