Effects of feeding pattern on body mass index (BMI)

Introduction

According to Eknoyan (2007), the body mass index (BMI) which is sometimes referred to as Quetelet index, is a measure for human body shape based on an individual’s mass and height. This was devised between 1830 and 1850 by the Belgian polymath Adolphe Quetelet during the course of developing “social physics”. It is defined as the individual’s body mass divided by the square of their height – with the value universally being given in units of kg/m². The BMI is used in a wide variety of contexts as a simple method to assess how much an individual’s body weight departs from what is normal or desirable for a person of his or her height. There is however vigorous debate, particularly regarding the value of the BMI scale in which threshold for overweight and obese should be set, but also about a range of perceived limitations and problems with the BMI.

While the formula previously called the Quetelet Index for BMI dates to the 19th century, the new term “body mass index” for the ratio and its popularity date to a paper published in the July edition of 1972 in the Journal of Chronic Diseases by Ancel Keys, which found the BMI to be the best proxy for body fat percentage among ratios of weight and height; the interest in measuring body fat being due to obesity becoming a discernible issue in prosperous Western societies. (Keys, Fidanza, Karvon, Kimura, Noboru and Henry, 1972). BMI was explicitly cited by Keys as being appropriate for population studies, and inappropriate for individual diagnosis. Nevertheless, due to its simplicity, it came to be widely used for individual diagnosis.

World Health Organisation (WHO, 2004) defines overweight and obesity as abnormal or excessive fat accumulation that may impair health. Although obesity can be determined by a number of methods, but body mass index (BMI) is the most commonly used measurement for many obesity researchers and health professionals (Afridi and Khan, 2004). Global rise in childhood overweight and obesity are attributable to some factors including high intake of energy-dense foods that contain elevated fat and sugars but low in vitamins, minerals and other healthy micronutrients, as well as inactive physical activity (Shehu, Onasanya, Oloyele and Kinta, 2010).

Conceptual framework

WHO (1995) states that ‘BMI’ provides a simple numeric measure of a person’s thickness or thinness, allowing health professionals to discuss overweight and underweight problems more objectively with their patients. However, BMI has become controversial because many people, including physicians, have come to rely on its apparent numerical authority for medical diagnosis, but that was never the BMI’s purpose; it is meant to be used as a simple means of classifying sedentary (physically inactive) individuals, or rather, populations, with an average body composition. For these individuals, the current value settings are as follows: a BMI of 18.5 to 25 may indicate optimal weight, a BMI lower than 18.5 suggest the person is underweight, a number above 25 may indicate the person is overweight, a number above 30 suggests the person is obese.

For a given height, BMI is proportional to mass. However, for a given mass, BMI is inversely proportional to the square of the height. So, if all body dimensions double and mass scales naturally with the cube of the height, then BMI doubles instead of remaining the same. This result in taller people having a reported BMI that is uncharacteristically high compared to their actual body fat levels. In comparison, the Ponderal index is based on this natural scaling of mass with the third power of the height. However, many taller people are not just “scaled up” short people, but tend to have narrower frames in proportion to their height. Nick Korevaar (a mathematics lecturer from the University of Utah) suggests that instead of squaring the body height (an exponent of 2, as the BMI does) or cubing the body height (an exponent of 3, as the Ponderal index does), it would be more appropriate to use an exponent of between 2.3 and 2.7 (as originally noted by Quetelet). (MacKay, 2010).

Body mass index (BMI) classification

Body Mass Index (BMI) is used to assess how much an individual’s body weight departs from what is normal or desirable for a person of his or her height. The weight excess or deficiency may, in part, be accounted for by body fat (adipose tissue) although other factors such as muscularity also affect BMI significantly. The World Health Organisation (WHO) regards a BMI of less than 18.5 as underweight and may indicate malnutrition, an eating disorder, or other health problems, while a BMI greater than 25 is considered overweight and above 30 is considered obese. (WHO, 2004).

Apart from BMI, BMI Prime, a simple modification of the BMI system, which is the ratio of actual BMI to upper limit BMI (currently defined at BMI 25) is also used to measure whether a person is underweight, normal, overweight or obese. As a definition, BMI Prime is the ratio of body weight to upper body weight limit, calculated at BMI 25. Since it is the ratio of two separate BMI values, BMI Prime is a dimensionless number, without associated units. Individuals with BMI Prime less than 0.74 are underweight; those between 0.74 and 1.00 have optimal weight; and those at 1.00 or greater are overweight. BMI Prime is useful clinically because individuals can tell, at a glance, by what percentage they deviate from their upper weight limits. For instance, a person with BMI 34 has a BMI Prime of 34/25 = 1.36, and is 36% over his or her upper mass limit (Gadzik, 2006).

These ranges of BMI values are valid only as statistical categories

Source: Adapted from WHO, 1995 and WHO 2004.

Overview of feeding pattern

The term feeding pattern (or feeding habits) refers to why and how people eat, which foods they eat, and with whom they eat, as well as the ways people obtain, store, use, and discard food. Individual, social, cultural, religious, economic, environmental, and political factors all influence people’s eating habits.

Why and how people eat

All humans eat to survive. They also eat to express appreciation, for a sense of belonging, as part of family customs, and for self-realization. For example, someone who is not hungry may eat a piece of cake that has been baked in his or her honour. People eat according to learned behaviours regarding etiquette, meal and snack patterns, acceptable foods, food combinations, and portion sizes. Etiquette refers to acceptable behaviours. For example, for some groups it is acceptable to lick one’s fingers while eating, while for other groups this is rude behaviour. Etiquette and eating rituals also vary depending on whether the meal is formal, informal, or special (such as a meal on a birthday or religious holiday).

A meal is usually defined as the consumption of two or more foods in a structured setting at a set time. Snacks consist of a small amount of food or beverage eaten between meals. A common eating pattern is three meals (breakfast, lunch, and dinner) per day, with snacks between meals. The components of a meal vary across cultures, but generally include grains, such as rice or noodles; meat or a meat substitute, such as fish, beans, or tofu; and accompaniments, such as vegetables. Various food guides provide suggestions on foods to eat, portion sizes, and daily intake. However, personal preferences, habits, family customs, and social setting largely determine what a person consumes.

What and how people eat is determined by a variety of factors, including economic circumstances, cultural norms, and religious restrictions. Here, an Iranian family sits on the floor and eats from a cloth laden with regional delicacies.

What people eat

In each culture there are both acceptable and unacceptable foods, though this is not determined by whether or not something is edible. For example, alligators exist in many parts of the world, but they are unacceptable as food by many persons. Likewise, horses, turtles, and dogs are eaten (and even considered a delicacy) in some cultures, though they are unacceptable food sources in other cultures. There are also rules concerning with whom it is appropriate to eat. For example, doctors in a health facility may eat in areas separate from patients or clients.

Obtaining, storing, using, and discarding food

Humans acquire, store, and discard food using a variety of methods. People may grow, fish, or hunt some of their food, or they may purchase most of it from supermarkets or specialty stores. If there is limited access to energy sources, people may store small amounts of foods and get most of what they eat on a day-to-day basis. In homes with abundant space and energy, however, people purchase food in bulk and store it in freezers, refrigerators, and pantries. In either case there must also be proper disposal facilities to avoid environmental and health problems.

Exposure to foods

There are innumerable flavours and food combinations. A liking for some flavours or food combinations is easily acceptable, but others must develop or be learned. Sweetness is a universally acceptable flavour, but a taste for salty, savoury, spicy, tart, bitter, and hot flavours must be learned. The more a person is exposed to a food—and encouraged to eat it—the greater the chances that the food will be accepted. As the exposure to a food increases, the person becomes more familiar and less fearful of the food, and acceptance may develop. Some persons only eat specific foods and flavour combinations, while others like trying different foods and flavours (Klimis-Zacas, 2001).

Influences on food choices

According to Kittler and Sucher (1998), there are many factors that determine what foods a person eats. In addition to personal preferences, there are cultural, social, religious, economic, environmental, and even political factors.

• Individual preferences: Every individual has unique likes and dislikes concerning foods. These preferences develop over time, and are influenced by personal experiences such as encouragement to eat, exposure to a food, family customs and rituals, advertising, and personal values. For example, one person may not like salad, despite the fact that they are a family favourite.
• Cultural influences: A cultural group provides guidelines regarding acceptable foods, food combinations, eating patterns, and eating behaviours. Compliance with these guidelines creates a sense of identity and belonging for the individual. Within large cultural groups, subgroups exist that may practice variations of the group’s eating behaviours, though they are still considered part of the larger group. For example, a hamburger, French fries, and a soda are considered a typical American Someone who is repeatedly exposed to certain foods is less hesitant to eat them. For example, lobster traditionally was only available on the coasts, and is much more likely to be accepted as food by coastal dwellers. Vegetarians in the United
  States, however, they eat “veggie-burgers” made from mashed beans, pureed vegetables, or soy, and people on diets may eat a burger made from lean turkey. In the United States these are appropriate cultural substitutions, but a burger made from horsemeat would be unacceptable.
• Social influences: Members of a social group depend on each other, share a common culture, and influence each other’s behaviours and values. A person’s membership in particular peer, work, or community groups impacts food behaviours. For example, a young person at a basketball game may eat certain foods when accompanied by friends and other foods when accompanied by his or her coach.
• Religious influences: Religious proscriptions range from a few to many, from relaxed to highly restrictive. This will affect a follower’s food choices and behaviours. For example, in some religions specific foods are prohibited, such as pork among Jewish and Muslim adherents. Within Christianity, the Seventh-day Adventists discourage “stimulating” beverages such as alcohol, which is not forbidden among Catholics.
• Economic influences: Money, values, and consumer skills all affect what a person purchases. The price of a food, however, is not an indicator of its nutritional value. Cost is a complex combination of a food’s availability, status, and demand.
• Environmental influences: The influence of the environment on food habits derives from a composite of ecological and social factors. Foods that are commonly and easily grown within a specific region frequently become a part of the local cuisine. However, modern technology, agricultural practices, and transportation methods have increased the year-round availability of many foods, and many foods that were previously available only at certain seasons or in specific areas are now available almost anywhere, at any time.
• Political influences: Political factors also influence food availability and trends. Food laws and trade agreements affect what is available within and across countries, and also affect food prices. Food labelling laws determine what consumers know about the food they purchase. Eating habits are thus the result of both external factors, such as politics, and internal factors, such as values. These habits are formed, and may change, over a person’s lifetime.

Effects of feeding pattern on body mass index (BMI)

In the opinion of Mahan (2000), whether underweight, normal, overweight or obese, your feeding pattern to a large extend plays a crucial role in addition to your lifestyle, the nature of your job and your environment. She also went further to state that the rate of your calorie intake verses energy expended determine your body mass index.

Feeding pattern and underweight

To carry out the normal day to day activities, the body means energy which is provided by intake of food. If your diet is unable to provide enough calories for the body as compared to the amount of energy expended in carrying out the normal daily activities, underweight is certainly to set it. (Gjesdal, 2008). One may be underweight because poor dietary decision which is not providing enough energy (calories). This can happen for a number of reasons. Stress or other emotional problems can sometimes cause a change in eating patterns that is hard to recognise.

The are several other reason which can lead to underweight, they include;

• Sickness
• Skipping breakfast or lunch and just eating snacks on the go
• Lost your appetite, perhaps because of stress or worries
• Trying to lose weight. Focused on being thin or looking a certain way than on being a healthy weight
• Not eating because of feeling of control or power

Although very many people feel good about themselves by remaining underweight. Zeratsky (2011) stated that being underweight can be bad for your health now and in the future, for the following reasons:

• If you are underweight, you are more likely to be lacking vital nutrients that your body needs to grow and work properly. Calcium, for example, is important for the maintenance of strong and healthy bones. Being underweight increases the risk of osteoporosis (fragile bone disease) later in life.
• If you are not consuming enough iron, you may develop anaemia (a lack of red blood cells), which leaves you feeling drained and tired.
• Your immune system is not 100% when you are underweight, making you more likely to catch a cold, the flu or other infections.
• For women, you may have interrupted periods and find it difficult to become pregnant. Women who are underweight can find that their periods stop. This increases the risk of problems with fertility.

Feeding pattern and overweight or obesity

Weight is a product of energy balance: energy intake versus energy expenditure. There are specific feeding pattern according to Schlosser (2001) that contribute significantly to overweight and obesity. There are:

• Restaurant and fast food consumption
• Large portion sizes
• Beverages with Sugar Added
• Fruits and Vegetables and
• Breakfast Consumption

Restaurant fast food consumption

Restaurant and fast food consumption now represents 32% of the total calories ingested per person, or one-third of daily total energy. The amount of calories consumed per eating occasion is greater from food prepared away from home as compared with food prepared at home.

Eating restaurant or fast food increases energy intake, and people who consume this food have a significantly higher odds of being overweight compared with those who do not eat fast food. There is a positive association between the frequency of eating restaurant or fast food and increases in body weight. Thus, multiple lines of evidence indicate that frequency of eating restaurant or fast food is associated with positive energy balance and excessive weight.

Large portion size

Portion size is closely related to restaurant and fast food consumption; the largest food portions. The greater the amount of food presented to people, the more food is consumed. When portions increase 50% and 100% above baseline energy intake increases an average of 120% and l30% above energy needs, respectively. Therefore, large portion sizes, as are frequently served in restaurants and fast food establishments, directly increase energy intake, which can lead to excessive weight.

Beverages with sugar added

Beverages with sugar added, a combination of soft drinks and fruit drinks, contribute over 40% of sugar added to the average diet. Studies have shown that people who increase intake of the amount of sugar-added beverages increase total energy intake and gain weight.

Fruits and vegetables

Energy density is a measure of energy content per weight of food. Foods with low energy density tend to have a high water and fibre content, such as fruits and vegetables, whereas high energy dense foods tend to have a high fat content. The intake of high energy dense foods results in greater energy intake than the intake of an equal weight of low energy density food. Consumption of energy dense foods with high fat content positively correlates with increased energy intake. However, this is not an issue only of fat intake because high energy dense food consumption increases energy intake independently of portion size and fat content.

Breakfast consumption

Those who do not eat breakfast have a significantly higher BMI than those who eat cereal or bread for breakfast. The exact mechanism of breakfast consumption and improved weight management is unknown. It has been shown that the number of eating episodes is inversely associated with the risk of obesity. Those who eat 4 or more times daily have a 45% lower risk of obesity compared with those who eat less than 4 times a day. Paradoxically, studies show that the total energy intake can be greater in those who eat breakfast. Whether it is the effect of consumption frequency on metabolism, decreased energy intake throughout the rest of the day, or greater health consciousness in terms of energy balance has not been determined. However, the overall nutritional benefits of breakfast consumption outweigh the risks.

Management of disproportionate BMI

Keys et al (1972) defined disproportionate BMI as a condition where a deviation from allowable (normal) BMI; in its real sense, the causes of underweight, overweight or obesity. Due to their peculiarity and associated health implication, it is paramount to manage these unhealthy conditions to enhance the quality of life of the individuals.

Management of underweight

SohI (2007), pointed out that most often, being underweight is a sign of an accompanying disorder. This disorder must first be dealt with in order to bring weight back to normal. In addition, to this treatment, physical activity may need to be modified and psychological counselling may be required. After the treatment of the primary disorder is successful, nutritional support may be provided along with dietary changes. The objectives of dietary modification are to restore the body to its normal weight, rebuild tissue and store nutrients, and maintain the desirable body weight The nutrient required for the management of underweight areas follows;

1. Energy: A nutritious high energy diet providing calories over and above the body’s requirement will result in weight gain. An increase of about 500 -1000 cal per day can result in a weight gain of approximately one kilogram per week.
2. Protein: A liberal intake of high quality protein will help in building up of muscle tissue. A daily protein intake of two grams per kilogram of body weight will be required. For example, if your body weight is 60 kg, you require 75-120 g protein.
3. Carbohydrates: A high carbohydrate intake is also necessary to meet the energy requirements of a malnourished body. The bulk of the diet however should not be increased as it cuts down food intake. Avoid taking more fibre than is necessary for regular bowel movement.
4. Fats: Fats aid in the weight gain process, but they should only be used in amounts that can be tolerated. Emulsified fats like butter, cream etc. are better tolerated by the body.
5. Minerals and vitamins: These must be provided in sufficient amounts in order to counter for nutritional deficiencies.

Management of overweight or obesity

According to Mayo Clinic (2013) the following ways are used in preventing and to manage overweight or obesity.

1. Monitor your weight regularly: People who weigh themselves at least once a week are more successful in keeping of excess pounds. Monitoring your weight can tell you whether your efforts are working and can help you detect small weight gain before they become big problems.
2. Know and avoid the food traps that cause you to eat: Identify situations that trigger you out of control eating. Try to keep a journal and write down what you eat, how much you eat, when you ear, how you are feeling and how hungry you are. And develop strategies for handling these types of situation and stay in control of your eating behaviour.
3. Exercise regularly: According to the American College of Sports Medicine (2000), you need to get 150 to 250 minutes of moderate intensity activity a week to prevent weight gain. Moderately intense physically activities include fast walking and swimming.
4. Eat healthy meals and snacks: Focus on low calories, nutrients dense foods such as fruits, vegetables and whole grain. Avoid saturated fat and limit sweet and alcohol. Ensure that you choose cod that promotes healthy weight gain and good health more often than you choose food that don’t.
5. Consistent: Stick to your healthy weight plan during the week.

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