Dietary Patterns

Abstract

Dietary patterns are defined as the quantities, proportions, variety, or combination of different foods, drinks, and nutrients in diets, and the frequency with which they are habitually consumed. Many social, demographic, and individual factors can have influence dietary patterns. A variety of food choices may benefit or harm health over time. Inappropriate dietary patterns are associated with risk of negative consequences in terms of diet-related chronic diseases, like cardiovascular disease, obesity, type 2 diabetes, and/or cancer. Dietary restriction behaviors can result in eating disorders including anorexia nervosa, bulimia nervosa, and binge eating disorder. Diet patterns are usually fairly well established, but they can change. Understanding of human nutrition can help to create eating patterns that help to achieve and maintain a healthy weight, reduce the risk of developing chronic diseases, and promote good health.

1. Introduction

Health risk can be defined as “a factor that raises the probability of adverse health outcomes” [1]. Risk can be connected with the causal chain of events over time, consisting of socioeconomic factors, environmental and community conditions, and individual behavior. These risk roots may be used as intervention points [2]. Behaviors with a strong influence on health are tobacco use, alcohol consumption, physical activity and diet, sexual practices, and disease screening [3]. An essential factor of human physical and mental development is diet. It is fundamental to human health and wellbeing across the lifespan [4].

Diet refers to the foods and beverages a person consumes, eats and drinks. Specific kind of diet is designed with the types of foods and beverages a person chooses, like vegetarian diet, a weight-loss diet. Thus, the term diet does not mean a restrictive food plan associated with weight loss. Dietary patterns are defined as the amounts, proportions, variety, or combination of different foods, beverages, and nutrients in the diet, and the frequency with which they are commonly consumed. Many social, demographic, and individual factors can influence dietary patterns. Not individual food selections, but the balance of foods selected over time can benefit or harm health [5].

Deterioration of health is associated with inadequate nutrition. The term ‘nutritional disorders’ covers a wide range of conditions that are primarily nutritional or nutrition is an important factor in their etiology. They may include deficiencies or excesses in the diet, chronic diseases that have been stimulated by a dietary component, as well as developmental abnormalities in which diet has no role in etiology, but for which specific dietary intervention is an essential part of management (e.g., phenylketonuria), the interaction of foods and nutrients with drugs, food allergies. Eating disorders are not primarily nutritional disorders, but have important nutritional effects and significant metabolic consequences [6].

The medical and psychiatric consequences of eating disorders are numerous. Some consequences can be reversed with weight restoration and resumption of normal eating behaviors. On the other hand, other complications, such as low bone mineral density (BMD), can persist after disease resolution causing is associated prolonged increased fracture risk [7]. Some form of ED can progress in severe obesity [8].

Eating disorders can affect people of all body weights and shapes. They can occur even in people, who look healthy, such as athletes. The origin of eating disorders has not been fully elucidated. Risk factors for all eating disorders involve a combination of genetic, biological, behavioral, psychological, and social issues [9]. These factors may interact differently in different people, causing specific dietary behaviors.

Psychometric test, so called the Eating Attitudes Test (EAT-26) is in use to identify the risk of eating disorders based on attitudes, feelings and behaviors related to eating. It is the most widely used standardized test, focused to examine socio-cultural factors in the development and maintenance of eating disorders. There is children’s version of the eating attitude test applicable in patients as young as 8 years old [10, 11]. With developing diagnostic criteria avoidant/restrictive food intake disorder can be distinguished from anorexia nervosa, bulimia nervosa, and binge-eating disorder [12].

Traditionally, inadequate nutrition has been simplified to identify health outcome primarily associated with a single nutrient or food. In last two decades, the focus for quantifying dietary exposures has shifted from single nutrients or foods to dietary patterns as dietary patterns can be more closely associated with overall health status and disease risk than consumption of individual foods or nutrients [13]. To have insight into overall diet it is necessary to analysis not only the foods, food groups, and nutrients, but also their combination and variety; and the frequency and quantity with which they are habitually consumed [14].

Analyzing food consumption as dietary patterns may provide a comprehensive approach to disease prevention or treatment. It can enhance conceptual understanding of human dietary practice, and provide guidance for nutrition intervention and education. The overall patterns of dietary intake might be easy for the public to interpret or translate into diets. Therefore, an emphasis on foods and beverages has improved translation to dietary recommendations for the general population [13, 14].

2. Dietary assessment methods

It is difficult to measure human behavior, especially to measure dietary exposures and capture the effects of eating behaviors. Diet intake of humans is assessed by objective observation and subjective report.

Objective observation can be done using a duplicate diet approach or food consumption record. Duplicate diet approach with direct analysis gives actual intake information throughout a specific period. Inherent strength is possibility of measurement of dietary exposures (e.g., environmental contaminants), but it not suitable for large-scale studies. Food consumption record is objective observation that ought to be done by trained staff at the household level. It obtains actual intake information throughout a specific period, but on individual level dietary consumption is not accurate. It is method of choice for those with low literacy or those who prepare most meals at home, and it is not suitable among those frequently eat outside the home [15].

Subjective assessment is possible using real-time recording (food diaries) or methods of recall. Self-reported recall methods can be in form of open-ended surveys such as 24 hours dietary recall - 24HR, dietary record - DR, dietary history since early life, or closed-ended surveys including food frequency questionnaire (FFQ). 24-Hour dietary recall uses open-ended questionnaires. It ought to be administered by a trained interviewer to obtain actual intake information over the previous 24 hours. However, there is possible recall bias as well as possible interviewer bias. Dietary record is subjective measure based on use of open-ended, self- administered questionnaires, so there is relatively large respondent burden (literacy and high motivation required, possible under-reporting). This method provides detailed intake data throughout a specific period. Dietary history has two parts: open- and closed-ended questionnaires administered by a trained interviewer. By this method, it is possible to assess usual dietary intake over a relatively long period [15].

Widely used direct assessment of dietary intake is FFQ. FFQ can has self- or interviewer- administered format. It is method of choice for large epidemiological studies to assess usual dietary intake estimated over a relatively long period (e.g., 6 months or 1 year). As diet can be influenced by social or individual factors, the FFQ should be developed specifically according to the interests of the research. FFQ can be food-based or dish-based, and focus may be on the intake of specific nutrients, or dietary exposures related to a certain disease. Semi-quantitative FFQs collecting data on the average portion sizes are in a closed format, and the simple FFQs that solely asks about the frequency or quantitative FFQs that queries about the amount of food consumption are based on completely open-ended questions [15, 16].

2.1 Meal patterns

To capture the interaction of nutrients and bioactive compounds within the whole diet, as people consume combinations of foods as meals and snacks, it is important to analyze meal patterns. To analyze contributions of meal patterns (also referred to as eating patterns) to energy and nutrient intakes and overall diet quality first the characterization, definition and measurement of ‘meals’ ought to be described. Meal may mean different things according cultural background, so different dimensions of meal patterns are in use to standardized criteria (for example, time-of day, number of hot/cold eating events). A main meal (for example, breakfast, lunch or dinner) or a smaller-sized meal (for example, supper or snack) are used to describe individuals’ eating patterns. The terms ‘eating occasion’ (EO) or ‘eating event’ are used in defining any occasion where food or drink is consumed, so incorporates all meal types. A minimum energy criterion as part of the meal definition also can be included. According to this criterion, EO is only treated as an EO if it contributes a minimum amount of energy (for example, 210 kJ). The different definitions of an EO greatly affected the results of the association between eating frequency and BMI.

Meals are multidimensional and can be classified according to three constructs: (1) patterning (for example, frequency, spacing, regularity, skipping, timing); (2) format (for example, types of food combinations, sequencing of foods, nutrient profile/content); and (3) context (for example, eating with others or with the family, eating in front of the television or out of the home). However, due to the limited dietary assessment methods available, most research has focused on meal patterning [17].

Two major eating patterns were identified, which were qualitatively similar across the two FFQs and the diet records. So called ‘prudent pattern’ is characterized by a higher intake of vegetables, fruits, legumes, whole grains, and fish, whereas so called ‘western pattern’, is characterized by a higher intake of processed meat, red meat, butter, high-fat dairy products, eggs, and refined grains [14].

The methods of choice to assess meals are food diaries and 24 h recalls with collection data on time of eating, and contextual information (for example, location of eating, presence of others), as well as self-identified meals. FFQ provide estimates of the frequency and types of foods that are usually consumed, and there is need for additional questionnaires to collect information on meal patterns [15].

There are some modifications of assessing eating patterns included in The Eating Disorder Examination (EDE). Besides questions related to meal frequency (breakfast, lunch, and evening meal) and snack frequency (midmorning, afternoon and evening), there are those assesing binge eating or purging behaviors (frequency of self-induced vomiting, laxative misuse, diuretic misuse, driven exercise, fasting, subjective and objective meassure of binge eating episodes) [18].

Evaluation of the eating behaviors patients ought to include analysis of 1) nutrient intake (protein, fat, carbohydrates, vitamins, and minerals) 2) dietary quality (nutrient density, percentage of dietary energy derived from the macronutrients protein, fat, and carbohydrates), and 3) food groups as sources for the macronutrients.

Dietary variables are quantitative and qualitative. The quantitative variables include energy and nutrients intake (weight units), and nutrient density per 4.2 MJ/1000 kcal. The qualitative variables are the relative distribution of energy between macronutrients (E%), the selection of food items and food groups, as well as calculation of nutrients per their sources [19].

2.2 Diet quality index

Diet quality index is the most common measure used to assess overall diet quality. It is constructed on the basis of prevailing dietary recommendations, thus it is a summary score of the degree to which an individual’s diet conforms to specific dietary recommendations. It reflects an individual’s adherence to the dietary guidelines for the country of the sample population (for example, the Healthy Eating Index (HEI), and the Dietary Guidelines Index (DGI)), or adherence to other dietary recommendation: a traditional Mediterranean diet score; Dietary Approaches to Stop Hypertension diet score; a dietary approach to prevent heart disease diet score (Optimal Macronutrient Intake Trial to Prevent Heart Disease score) [14].

3. Eating patterns in ED

Main characteristic of anorectics eating behavior is a restriction of overall food intake, while vomiting/purging and intermittent starvation of bulimics is main mechanism of avoiding weight gain. The most commonly findings of food restriction are specific carbohydrate avoidance and, to a lesser degree, fat exclusion. However, anorectics and bulimics differ from each other with regard to food consumption patterns. Bulimics avoid bread and cereals, so they have less of their protein, fat, and carbohydrate energy from the bread/cereal group. On the other hand, anorectics prefer bread and cereals, at the same time trying to eliminate fat from their diets. Bread and cereals are thus the distinguishing feature between the ED groups.

The bread/cereal avoiding can be explain with bulimics attitude that carbohydrates from bread and cereals are particularly “fattening”. Even their fear of carbohydrates, their diet contains a substantial proportion of carbohydrates from fruits and vegetables. Mostly, bulimics rate vegetables, fruit, lean meat as “safe”, while cookies, bread, cakes, and fried are consider as “forbidden” foods. Consequence of this is that if the bulimic eats anything outside her preestablished dietary “allowance,” she immediately resorts to binge eating. As the food choice among bulimics has often been demonstrated to be very narrow the non-purged diet consisted mainly of salads and diet sodas.

Anorectics on the other hand, have often been found to eat the same food every day, with explicated fear of “fatty” products [19, 20].

3.1 Eating patterns in individuals with anorexia nervosa

The mean generalization of AN is caloric restriction that resulted in weight loss. Restriction is greater during the more severe phases of the disorder. Beyond this restriction great variability in the diet patterns can be found. A regular meal and snack pattern can have approximately six eating episodes per day, in form of three meals and three snacks per day. Mostly, regular meals pattern is associated with a high-quality diet but restricted calorie. Inadequate calories during each eating episode are due to nature of insufficient quantities, or low caloric density food choices. This mainly rigid dietary pattern is caracteristic of restrictive type AN. Irregular eating patterns have fewer eating episodes on purge-only days, and more eating episodes on binge days (with or without purging) [16, 17]. Thus, less regular eating patterns are associated with loss of control eating. Meals are skipped with long intervals without eating at binge eating/purging type AN. Those with the BE/P type consume breakfast and dinner significantly less often than those with restricting type, and consume mid-morning snack and mid-afternoon sack significantly less often than those with restricting type. Among those with AN-BE/P, skipping dinner is associated with a greater number of binge eating episodes, while skipping breakfast is associated with a greater number of purging episodes. It may be the main mechanism associated with the development and maintenance of binge eating and purging. This mechanism suggests that dietary restraint leads to binge eating, which may lead to purging, and this in turn leads to a vicious cycle of increased efforts to restrict eating again. There is possibility that AN-BE/P often have higher eating disorder severity, more co-morbidities and worse prognosis than patients with AN-R [18].

Beside caloric restriction stereotyped food choices are characteristic of AN. Some food groups are chosen less often like bread and cereals, meat, cured meats, fatty foods, sweet foods and fried foods, but vegetables are chosen more often. Diet intake analyze has shown that restrictive anorexic females have a lower macronutrients intake than do healthy people, and illness duration specialy negatively correlats with the amount of fat in the diet. On the other hand, the relationship between unsaturated and saturated fats (MUFA + PUFA/SFA) is not significantly different between patients and healthy people. There are significant differences in some micronutrients content between the groups. There is tendency of lower intake of vitamin A and vitamin C, as well as sodium, phosphorus, zinc, copper, and selenium. It is established that, compared to controls, lower proportion of patients reached the DRI for thiamine, vitamin B6, calcium, iron and copper, although a higher proportion of patients reached the DRI for folate. Not only the majority of patients do not reach the DRI for pantothenic acid, folate, vitamin D, calcium, magnesium, iron, iodine and zinc, but that something similar occurs among healthy people [21, 22].

Not only AN, but avoidant/restrictive food intake disorder (ARFID) represents with avoidant or restrictive eating, but it is clearly different from AN. In patients with ARFID there are no disturbed cognitions about weight and/or shape, or a wish to lose weight. There are similar physical signs and symptoms as at AN patients, due to semi-starvation, like weight loss or lack of weight gain, nutritional deficiencies, reliance on tube feeding or oral nutritional supplements and/or disturbances in psychosocial functioning. On the other hand, ARFID patients are younger than AN patients and have a greater percentage of males. There are specific behaviors and symptoms in the ARFID group, including food avoidance, decreased appetite, abdominal pain, and emetophobia. While the degree of malnutrition is similar to that of patients with AN, those with ARFID have a greater dependence on nutritional supplements, fears of vomiting and/or choking, and texture/sensory issues pertaining to food. It can be explained by body preoccupation with somatic concerns. Some children express fears of physical illness due to issues related to shape/weight, e.g. high cholesterol and/or obesity leading to heart isease, either because of personal experiences with relatives or information in their school curriculum. Sometimes, worries about being fat, can be connected with events in the family’s medical history, like recent myocardial infarction at an overweight relative. This event can be processed making illogical associations based on the cognitive developmental stage. This knowledge may then trigger restrictive eating behaviors. Thorough history-taking can often elicit this information [23].

3.2 Eating patterns in individuals with bulimia

The bulimics eating pattern can be described as intermittent starvation (i.e. non-purged diet during the restrictive or compensatory phase), interrupted by bouts of binge eating [18]. In the single-course normal meal, bulimics eat less on average than healthy nonbulimics. In patients with BN, objective food consumption ranges, in a sence of total energy consumption, as well as of energy intake per binge episode and the frequency of binge episodes. There is significant difference in the calories consumed by patients with BN during binge episodes compared to nonbinge meals [24, 25].

Thus, objective food consumption in a laboratory setting ranged from 7101 to 9360 kcal per 24 h and from 3030 to 4479 kcal per binge episode. However, subjective food records showed total energy consumption to range from 3117 to 4275 kcal per day and from 1173 to 2415 kcal per binge episode [22].

Even energy deprivation and malnutrition are often thought to be key factors in the maintenance of bulimia nervosa, it is unclear how much energy is actually available to BN patients’ metabolism because the contribution of food consumed during binge eating is hard to evaluated [26].

3.3 Differences in binge behavior between bulimia nervosa and binge-eating disorder subjects

Binge eating is defined as the consumption of a large amount of food in a short period of time accompanied by a sense of lack of control over eating [12].

Binge eating has historically been associated with bulimia nervosa and the bulimia nervosa subjects eat more than BED subjects when presented with the same types of foods. It can be explained with fact that they allow themselves to purge following a binge. The frequency of binge episodes among individuals with BN ranged from 5.7 to 10.9 episodes per week, while the frequency of binge episodes among BED ranges from 10.7 to 17 episodes per 28 days [25].

Bulimics consumed increased caloric intake mainly because 37% of their meals were greater than 1000 calories. The binge foods consisted primarily of sweet desserts and snacks with a high fat content. This is connected with the avoidance of forbidden sugar and carbohydrate foods during nonbinge periods so cravings for these foods are reflected in their binges.

Thus, the binges of bulimics are higher in carbohydrates and sugar than those of individuals with BED. Generally, those with BED eat more fat, less protein, and an equal amount of carbohydrates when compared to nonbinge eaters what can be associated with their preference to choose foods eaten at a meal for binges [27, 28].

A disruption of circadian feeding patterns in sense that large meals are consumed mostly during the afternoon and evening have been seen at BN and BED. According to the diagnostic criteria, individuals with NES (night eating syndrome) should consume at least 25% of their total caloric intake after the evening meal. However, a delay in the circadian pattern of food intake (NES) may not be simply a variant of BED or BN but rather a separate entity that may lead to a more severe disorder [25].

4. Conclusions

Two EDs, anorexia nervosa (AN) and bulimia nervosa (BN), have historically been the primary EDs of focus. The DSM-5 updated diagnostic criteria for these disorders added two more: binge-eating disorder (BED) and avoidant/restrictive food intake disorder (ARFID) [12, 29].

Based on past versions of the DSM over 50% of patients met criteria for Eating Disorder Not Otherwise Specified (EDNOS). Recognition new disorders makes possibility to take a developmental, or life-span, approach to all disorders.

Patients with ARFID are less likely to report typical ED symptoms, e.g. purging behaviors and excessive exercise. They are younger, and a higher likelihood of being male. Children and adolescents with ARFID are more likely to present at a younger age with significant weight loss or failure to gain appropriate weight, are more dependent on oral or enteral nutritional supplementation, and have significantly more fears of choking and/or vomiting, and texture and/or sensitivity issues regarding food. They do not have body image distortion. However, some of them have body preoccupation with somatic concerns. Thus, evaluation of a young patient with possible ARFID versus AN, include probe about body concerns that need to be distinguished from body image distortion [23].

Disturbances in eating patterns is main characteristic of EDs. Dietary behaviors differ across the eating disorder diagnostic spectrum. For identification and classification of each EDs, it is important to define the associated eating patterns. Individuals with AN typically follow rigid dietary behaviors in meaning their meal times are fixed, they reduce portion sizes, they choose low caloric food. On the other hand, individuals with BN and BED tend to have more chaotic and inconsistent dietary behaviors and greater intra-individual variability. When they are not engaging in binge eating, individuals with AN-BE/P and BN have been found to attempt to restrict their caloric intake for the purpose of weight control, whereas individuals with BED have been found to be less likely to reduce their food consumption outside of binge eating with a slight tendency towards overeating [30].

The detailed description of the disturbances in eating behavior not only helps to identify diagnostic criteria associated with each disorder, but also provide a foundation for the development of treatment interventions [29]. Individuals who restrict caloric intake or consume meals and snacks with irregular frequency tend to engage in more frequent binge eating episodes. An irregular meal pattern of less than three meals a day is associated with more binge-eating episodes Specific dietary restriction behaviors, like reducing caloric intake by reducing portion sizes can increase risk for binge eating behaviors. Thus, it is important to identify dietary restriction behaviors that are associated with the onset of binge eating to cease it. A decrease in dietary restriction is a critical component for a successful reduction of binge eating behaviors across eating disorder diagnoses [30].

Conflict of interest

The author declares that she has no competing interests.

Abbreviations

24HR	24 hours dietary recall
AN	anorexia nervosa
AN/BN	anorectic bulimics
BE/P	binge eating/purging
BMI	body mass index
BN	bulimia nervosa
BMD	bone mineral density
DSM	Diagnostic and Statistical Manual of Mental Disorders
DGI	Dietary Guidelines Index
DR	dietary record
DRI	dietary reference intakes
EAT-26	Eating Attitudes Test
ED	eating disorder
EDE	Eating Disorder Examination
EDNOS	Eating Disorder Not Otherwise Specified
EO	eating occasion or eating event
FFQ	food frequency questionnaire
HEI	Healthy Eating Index
MUFAs	monounsaturated fatty acids
NES	night eating syndrome
PUFAs	polyunsaturated fatty acids
SFAs	saturated fatty acids