C ARBOHYDRATES AND M OOD IN O BESE I NDIVIDUALS

13.3.3 C ARBOHYDRATES AND M OOD IN O BESE I NDIVIDUALS

Obesity is an increasingly significant problem in many countries. In the U.S., a recent random-digit telephone survey of 195,005 adults aged 18 or older revealed

that the prevalence of obesity increased from 19.8% in 2000 to 20.9% in 2001, an increase of 5.6%. 80 This is a trend that has been occurring for decades. 81 The significance of such a continuing increase in weight is apparent in the data demon- strating that being overweight and obese is significantly related to a variety of negative health consequences, such as diabetes, high blood pressure, high choles- terol, asthma, arthritis, and poor health status. 80

Obesity is typically defined as excessive storage of energy in the form of fat. 81 While obesity is a complex multifaceted problem with a variety of antecedent and

predisposing factors, overeating is, to many health practitioners and the general public, the primary cause. 82 A focus on the overconsumption of calories is counter- productive and probably will contribute little to our understanding of the cause and treatment of obesity. However, dietary intake is a significant variable. One of the variables that has received attention is the type of food preferred by obese individuals. Obese men list fat and fat/protein foods (meat dishes) as the type of foods they most prefer, whereas obese women list carbohydrate/fat foods and foods that are sweet,

such as doughnuts, cookies, and cakes. 83 It is this desire for sweet carbohydrate- and fat-rich food that primarily exists in obese women that has been of interest to

a number of researchers. The desire for sweet carbohydrate- and fat-rich foods has been expressed as a carbohydrate craving. The hypothetical construct of carbohydrate craving in obese individuals is somewhat controversial, with some researchers believing that it is a

meaningful construct 84 and others 58,85 considering it a useless construct and an impediment to scientific progress in obesity research. In spite of the controversy

over its validity, it is a construct that continues to appear in the literature and one that is expressed by many obese individuals.

Dietary Carbohydrates as Mood and Performance Modulators

Although the construct of carbohydrate craving among the obese is controver- sial, the fact still remains that the obese, particularly obese women, express a preference for sweet carbohydrate- and fat-rich foods. Interestingly, foods from a fat food group were the least preferred, as were foods from a sugar food group. 83 Consequently, it is the combination of these two food groups that produces a highly desired food. It is also interesting to note that the consumption of sweet carbohydrate- and fat-rich foods occurs primarily in the form of snacks consumed in the afternoon and evening. 86,87

While there is consistent evidence that obese individuals, particularly obese women, demonstrate a preference for and consumption of sweet carbohydrate- and fat-rich foods, there is some disagreement as to the frequency with which these

individuals report craving such foods. Wurtman et al. 87 reported significant difficulty in finding overweight noncarbohydrate cravers, whereas other studies 85,86 seem to

have little difficulty finding such individuals. The difference is probably due to the way in which these different studies identify so-called carbohydrate cravers, because

up to 80% of obese women list sweet carbohydrate- and fat-rich foods as one of their preferred foods. 83 The evidence therefore indicates that a significant percentage of obese individuals, particularly women, experience a craving or intense desire for sweet carbohydrate- and fat-rich foods and consume these foods primarily as snacks in the afternoon and evening when they experience a craving for such foods. 86

One of the interesting questions is why obese individuals would demonstrate a preference for and consumption of sweet carbohydrate- and fat-rich foods primarily in the afternoon and evening. It has been reported that overweight individuals

reporting carbohydrate cravings suffer from transient depression 88 and state that they feel restless, tense, and unable to concentrate prior to consumption of the snack and calm, relaxed, and able to concentrate after snack consumption. 89 Such statements suggest that these individuals are engaged in a form of self-medication where food is used to induce a positive mood state. The notion that emotions induce eating in obese individuals has received significant attention, and the literature suggests that emotional eating is very prevalent in the obese and that the major determinant of emotional eating is its ability to reduce negative emotions such as anger, depression, and loneliness. 90

The hypothesis that obese individuals engage in a form of self-medication with sweet carbohydrate- and fat-rich foods is rather controversial and has received conflicting support. Lieberman et al. 84 found that obese individuals who reported carbohydrate cravings and consumed carbohydrate-rich snacks during a 3-day period experienced a decline in depression 2 h after consumption of a carbohydrate-rich lunch. Obese noncarbohydrate cravers experienced an increase in depression and fatigue and a decrease in alertness 2 h after the consumption of the carbohydrate- rich lunch. This study clearly supports the idea that obese carbohydrate cravers experience a positive mood alteration following a carbohydrate-rich meal, whereas

obese noncarbohydrate cravers do not. However, neither Toornvliet et al. 85 nor Reid and Hammersley 91 found any mood-enhancing effect from a carbohydrate-rich meal. The failure to find an effect in these two studies may be due to the nature of the way in which the research participants were selected. Reid and Hammersley used individuals who were obese, but no attempt was made to determine if they were

Functional Food Carbohydrates

carbohydrate cravers. Toornvliet et al. 85 distinguished carbohydrate cravers from noncarbohydrate cravers based on their assessment of 3-day food records. Lieberman et al. 84 distinguished carbohydrate cravers from noncarbohydrate cravers based on self-report and actual selection of carbohydrate-rich snack foods. Also, Lieberman et al. 84 reported difficulty in finding noncarbohydrate cravers, whereas Toornvliet et al. 85 identified more noncarbohydrate cravers than cravers from their assessment of food records. This would strongly suggest that significant differences existed in the characteristics of the samples studied. Also, Corsica 92 has demonstrated that, when dysphoric, women who report craving carbohydrates selectively choose a carbohy- drate-rich beverage vs. a nutrient-balanced beverage. Additionally, when the partic- ipants consumed the carbohydrate-rich beverage, they reported a greater improve- ment in depression than when they consumed a protein-rich beverage. The evidence therefore seems to be tilted in the direction of supporting the idea that obese carbohydrate cravers self-medicate with sweet carbohydrate- and fat-rich snacks to experience an improvement in their mood.