Alcohol Use and Abuse: Effects on Body Weight and Body Composition

Abstract

Ethyl alcohol (referred to in this chapter as alcohol) is one of the most widely consumed substances in the world and provides significant quantities of energy to living organisms. The energy density of pure ethanol is 7 kcal/g (equivalent to 29 kJ/g), i.e., second only to plant and animal lipids (i.e., fat), which contain 9 kcal/g and significantly higher than the energy density of proteins and carbohydrates (4 kcal/g) [1]. The energy provided by pure alcohol is often referred to as empty calories, as this simple molecule is not a source of carbohydrate, protein, fat, minerals, or vitamins. In order to meaningfully compare alcohol intake between studied individuals, regardless of type of drink, a standardized measure of alcohol consumption was defined. Its definition differs slightly between studies and ranges from 10 to 15 g of pure ethanol per drink [2, 3]. In many clinical studies, one alcoholic drink is defined as 13.6 g of pure alcohol [4]. A standard drink corresponds to 12 oz of beer (330 ml), 5 oz of wine (140 ml), or 1.5 oz of liquor or vodka (40 ml). Correspondingly, a 12-oz can of regular beer contains approximately 145 calories, a 5-oz glass of wine ∼135 cal, and 1.5-oz serving of spirits ∼130 cal [5]. However, certain alcoholic drinks such as sweet wine or beer may contain additional calories in form of simple and complex carbohydrates. In such cases, the caloric content of a drink may be significantly higher than 100 kcal. Thus, alcohol consumption may introduce a significant amount of calories into the diet. Understanding the contributions of alcohol consumption to individual’s energy balance is of vital importance, as excessive consumption may significantly increase caloric intake and place the individual at increased risk for overweight or obesity and the associated biomedical conditions (see below).