Heavy alcohol consumption during the crucial developmental period of adolescence is an important public health concern in both in developed [1, 2] and developing countries [3, 4]. Adolescent alcohol abuse/dependence has many known harmful health and social consequences, such as school failure , crime and violence , increased risk of adult alcohol dependence/abuse, illicit drug use, social adversity  cardiovascular disease , and is also strongly associated with a wide range of other health risk behaviours . Examination of the effects of heavy alcohol use during adolescence has expanded in recent years , however, the consequences for adolescent nutritional status are largely unknown at this time.
The 2008 South African Youth Risk Behaviour Survey (YRBS) reports that 35% of a national sample of grade 8 to 11 adolescents (n = 10 270) reported drinking alcohol on one or more days in the month preceding the survey. Nationally, 29% of adolescents had engaged in past month binge drinking, a significant increase from the rate of 23% in the 2002 YRBS . Significantly more learners in the Western Cape Province (41%) had engaged in binge drinking in the past month when compared to the national average of 29% .
Globally, adolescents are recognized as a nutritionally at-risk group . High nutritional demand for growth and development, poor eating behaviour during adolescence [11–13], and a propensity for risk-taking behaviours are all threats to nutritional adequacy . Adolescent eating patterns are typically characterised by high consumption of sweetened beverages, increased intake of energy-dense nutrient-poor foods, and frequently skipping meals, particularly breakfast [13–16]. South African adolescents are no exception [17, 18]. Poor nutrition during this life-stage, which is also characterised by the adolescent growth spurt, may be associated with stunting (chronic undernutrition), underweight (chronic negative energy balance), or being overweight or obese (chronic positive energy balance).
Alcohol is energy-dense and energy provided by alcoholic drinks is derived from the alcohol (29 kilojoules per gram) and the carbohydrates (17 kilojoules per gram) they contain, with most drinks containing negligible amounts of other nutrients . Heavy alcohol use may affect total energy intake in a variety of ways. First, if alcohol energy replaces food energy (thus no change in total energy intake) dietary quality is reduced, with poor intake of essential macro- and micronutrients, even though energy needs may be met. This nutrient inadequacy increases the risk for nutrient deficiencies, which may enhance the risk for stunting (low height-for-age) . Second, heavy alcohol use may result in a more significant reduction in dietary intake with energy from alcohol not compensating for the total loss of dietary energy intake. Inadequate energy and nutrient intake could manifest in the adolescent as underweight (low body mass index (BMI)-for-age) or possibly stunting . However, it must be borne in mind, that the greatest risk for stunting remains poor nutrition during the first two years of life . Third, alcohol containing drinks could be ingested in addition to usual food intake, resulting in increased total energy consumption, compounding the risks for weight gain and being overweight/obese (high BMI-for-age) .
A recent review examined the outcomes of preload studies of the effects of alcohol on subsequent food intake in adults, and reported that in the short-term, energy ingested as alcohol is additive to energy consumed from other sources, suggesting that alcohol promotes short-term passive over-consumption of energy . According to Yeomans (2010), alcohol is very inefficient at triggering the satiety mechanisms involved in short-term control of food intake. Adult studies have further found alcohol use to be positively associated with BMI or obesity [23–25]. The work by Oesterle and colleagues, namely that chronic heavy drinkers aged 10 to 24 years were nearly four times more likely to be overweight or obese at age 24, suggests that this may be true for adolescents . The positive association between alcohol and tobacco use and unhealthy eating habits such as consuming sweetened carbonated drinks, sweets and snacks, as reported in adolescents [27–30], further compounds these risks. As such, it is reasonable to speculate that dietary changes associated with heavy alcohol use in adolescence may include a higher intake of energy-dense foods, thus contributing to increased total energy intake. Thus, heavy alcohol use during adolescence may promote overweight and obesity via the additive effect of alcohol energy as well as dietary changes favouring energy-dense items, resulting in a persistent positive energy balance.
The 2002 and 2008 YRBSs in South Africa show overnutrition to be a greater problem in this age group than undernutrition, with an increase in the prevalence of overweight and obesity nationally from 2002 to 2008 (21 to 25%), especially in the mixed ancestry population (16.6 to 22.4%). The prevalence of overweight and obesity was consistently greater in females nationally, in the Western Cape Province, and in the mixed ancestry population group [4, 10]. This follows a widely recognised global trend in which overweight exceeds underweight in females in more than half of the world's developing countries .
Heavy alcohol ingestion can compound the problem of positive energy balance in usual dietary intake, increasing the risk for weight gain. Thus, it is argued that heavy alcohol use during adolescence may increase the risk for overweight and obesity. At this time, studies investigating the association between heavy alcohol use, energy balance, growth and weight status of adolescents are lacking internationally, with no such studies having been conducted in South Africa.
The current study examines anthropometric indices of growth and weight status in treatment-naive, 12 to 16 year old community-dwelling adolescents with alcohol use disorders (AUDs) in comparison to matched light/non-drinking control adolescents, both groups without co-morbid substance use disorders (SUDs) or psychiatric disorders, as part of a larger study exploring the effects of heavy alcohol use on brain structure and function. The inclusion of adolescents without co-morbid externalizing disorders or SUDs, allows us to study the effects of AUDs on growth and weight indices without the confounding effects of other substance abuse or externalising disorder risk factors. It is hypothesised that anthropometric indices of growth and weight status may be different in adolescents with AUDs compared to light/non-drinking control adolescents.