Good nutrition is essential to health. Inadequate nutrition leads to many diseases and affects the primary condition and response to treatment (Sydney-Smith 2000). Sixty per cent of deaths are related to nutritional factors, for example, diabetes-associated cardiovascular disease (Middleton et al. 2001). In particular, micronutrients and protein intake are often inadequate and mineral deficiencies are common in Australia, especially in people living in poverty.

Diets low in vitamins and minerals are also deficient in antioxidants that modulate oxidative tissue damage. Oxidative tissue damage is implicated in the development of long-term diabetic complications and is compounded by smoking, alcohol and chronic inflammatory diseases, see Chapter 8. Vitamins C, E, and A and some plant chemicals (phytochemicals) are naturally occurring antioxidants derived from a well balanced diet.

Obesity is defined as excess body fat and is now recognised as a disease in its own right (Marks 2000). Obesity is emerging as a complex phenomena caused by a number of inter-related factors including a high fat energy-dense diet, inadequate amounts of exercise, and genetic, hormonal and environmental factors (Brunner & McCarthy 2001; Bouchard et al. 2004). The estimated risk of becoming obese using data from the Framingham Study suggests a normal weight person has a 50% long-term risk of becoming overweight and 25% risk of becoming obese (Reynolds et al. 2005). Significantly, a number of studies suggest underweight might confer greater health risks in older people (Diehr et al. 1998, 2008).

Some medicines such as corticosteroids, antipsychotics, birth control medicines, insulin, sulphonylureas, and thiazolidinediones (TZDs) also contribute to weight gain, see Chapter 5. There is increasing evidence that ethnicity, difficult social environments, social isolation, being teased about weight, low self-esteem and low global self-worth contribute to obesity in children (Goodman & Whitaker 2002; Eisenberg et al. 2003). Contributing environmental factors include excess television viewing, insufficient physical activity, which might be influenced by living in unsafe areas, and high consumption of fast foods (Burdett & Whitaker 2005).

The prevalence of overweight and obesity are increasing globally but there are differences among populations and among ethnic groups within populations. Rates of overweight and obesity are also increasing in children and adolescents. A child with one overweight parent has a 40% chance of becoming overweight and the risk increases to 80% when both parents are overweight. Significantly, obesity makes it difficult for health professionals to perform some preventative health care interventions such as Papinocolou smears and mammograms and overweight women are more likely to have false-positive results than non-obese women (Elmore et al. 2004).

People with central or abdominal obesity are at increased risk of obesity-related diseases such as metabolic syndrome, Type 2 diabetes, dyslipidaemia, fatty liver, and therefore are at significant risk of cardiovascular disease. Obesity is a risk factor for shortened life expectancy in younger but not older people (Heiat et al. 2001) and the importance of overweight and obesity as predictors of health status decline in people >65 years. In fact, some research indicates being overweight is associated with better quality of life and health status in this age group (Stevens 2000).

Weight circumference is significantly correlated with triglycerides, CRP, cholesterol and glucose but not HbA_1c in healthy women (Behan & Mbizo 2007). Likewise, the INTERHEART Study Group (2005) demonstrated that waist circumference is strongly related to myocardial infarction but the level of risk is still debated. Physical fitness may reduce the inflammation associated with abdominal obesity and lower cardiovascular risk (Zoeller 2007).

Various cardiovascular risk scores have been developed based on parameters such as age, gender, total cholesterol, LDL, systolic blood pressure, being treated for hypertension and smoking, for example, The Framingham Risk Score (Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (2002) and the Systemic Coronary Risk Evaluation (SCORE) (Third Joint Taskforce of European and Other Societies on Cardiovascular Disease Prevention in Clinical Practice (2003). However, a 12-year US study of people in their 60s suggests obese people live as long as people of normal weight and are less likely to develop diabetes or lipid abnormalities if they are fit. However, at BMI >30 people experience difficulty performing usual activities of daily living and develop other obesity-related disorders such as musculoskeletal disease that cause pain and have lower muscle strength and reduced cardiovascular fitness (ABC Health and Well Being 2007). Thus, the focus of weight management must also include reducing disability.

Other obesity-related diseases include osteoarthritis, rheumatoid arthritis, and other musculoskeletal diseases, some forms of cancer, for example, breast, oesophagus, colorectal, endometrial and renal cell, sleep apnoea and daytime sleepiness, gout, urinary stress incontinence, surgical complications, and maternal obesity has been associated with a higher incidence of birth defects.

There is a complex association between nutrition and stress and overweight/obesity. Stress affects eating behaviour: most people eat more and gain weight; 30% reduce weight (Stone et al. 1994) but the reasons for the increased intake are unclear. Likewise, Fiegal et al. 2002) found people are concerned about life stress and 50% eat more calorie dense food when they are stressed, and undertake less activity. A suggested mechanism for the effect of stress on weight is that cortisol levels are increased during stress, which stimulates appetite: managing stress reduces stress-related intake. In addition, chronic low level stress reduces insulin sensitivity and contributes to abdominal obesity and metabolic syndrome.

Significantly, 45% of women and 23% of men think they are overweight and 20% of underweight women think they are overweight and are dieting to lose weight (Better Health Channel, January 2008). People use a range of self-initiated strategies to lose weight, which are often successful initially, but regain half to two thirds of the weight lost in the first 12 months and nearly all within 5 years. In contrast, the NHANES 1999–2002 showed 58% of people who lost >5% of their bodyweight maintained the weight loss for up to 5 years. Factors associated with weight gain included:

• Mexican-American peoples.
  
• Significant weight loss.
  
• Fewer years since reaching their maximum weight.
  
• Long time spent watching TV including children.
  
• Attempting to control weight.
  
• Sedentary lifestyle.
  
• Frequent attempts to diet were associated with increased risk of developing an eating disorder.

Ethnic differences could partly explain the different findings. In addition, people who are supported are more likely to stay motivated than those who ‘go it alone.’ Selfperception and body image influence quality of life and mood and there is a pervasive association between perception of being overweight and depression and disordered body image.

Measuring obesity is difficult. A number of methods are used. Each has advantages and disadvantages.

Crude weight

Weighing people is the simplest way to estimate obesity using height/weight standards. It does not take into account muscular builds at different heights or that lean body mass weighs more than fat tissue. Mild obesity = 20– 40% overweight; moderate obesity = 41–100%, and severe obesity = twice the actual weight for height.

Body Mass Index

The Body Mass Index (BMI), sometimes referred to as Quetelet’s Index, is a simple method of assessing obesity but, like crude weight, it does not take into account muscular builds at different heights. However, despite the limitations BMI >30 generally indicates excess adipose tissue. BMI should be interpreted according to growth charts in children. BMI is calculated using the following formula: Weight in kilograms divided by height in metres squared.

Waist-hip ratio

The waist-hip ratio (WHR) is measured with the person standing and specifically measure abdominal obesity. The waist is defined as the largest abdominal circumference midway between the costal margin and the iliac crest. A WHR >90 in men and >80 in women is generally regarded as an accurate predictor of obesity-related disorders, independently of the BMI. WHR can be affected by postprandial status, time of day, and depth of inspiration to an unknown degree. It includes both intra-abdominal fat (the area of interest) and subcutaneous fat, but it is not clear how to adjust the WHR for subcutaneous fat. There are also differences among ethnic groups that need to be considered. It is useful to record the WHR on a regular basis.

Other ways of measuring body fat include:

• Dual energy X-ray absorptiometry (DEXA), which is often used in research and to determine risk of osteoporosis. Lean body mass, skin fold thickness, densitometry hydrostatic weighing and bioelectrial impedence analysis are other ways to measure obesity.

Strategies used to measure food consumption:

A number of tools are used to estimate food intake over various time periods. These include:

• Food records: the individual keeps a detailed record of their intake for varying periods from 3 to 7 days. Maintaining a food record can be burdensome and requires the person to be literate. In addition, actually recording intake often influences the person to consider what they eat and change their usual eating pattern.
  
• Food frequency questionnaires (FFQ) to retrospectively estimate usual dietary intake over time, usually 6–12 months. Information is collected about specific types of food and the quantities and frequency with which they are consumed. Short (60 foods) and long (100 foods) FFQs are used. FFQs must be culturally relevant and a number of culturally relevant forms exist. Modified FFQs identify dietary fat, fibre, fruit, and vegetable intake.
  
• Dietary recall, often over 24-hours to estimate current intake. Accuracy is influenced by the individual’s ability to recall the type and quantity of food consumed. Most people underestimate their intake.
  
• Visual estimation, where trained observers monitor an individual’s food choices, classifies foods using a rating scale and estimates serving sizes. This is intimidating and may influence the individual’s food selection. Nurses can undertake this type of monitoring process.
  
• Plate waste methodology, which has been used extensively in studies of food intake in school children but is not practical in clinical practice.
  
• Screening tools such as;
  
  
  
  • Malnutrition Universal Screening Tool (MUST) for adults (Malnutrition Advisory Group (MAG) 2000).
    
  • Nutritional Risk Screening (NRS-2002) for hospital settings.
    
  • Mini Nutritional Assessment (MNA^©) for the elderly (Vellas et al. 1999).
    
  • The Healthy Eating Index (HEI) and Modified HEI for children and adolescents (Feskanich et al. 2004).
    
  • Biomarkers to identify specific food components in body fluids or tissue, which independently reflect intake of the particular food.

Obesity and Type 2 diabetes are chronic conditions and long-term management strategies are needed. Usually a combination of strategies is most effective especially when they are developed in consultation with the individual. In the first instance, energy-dense food intake such as simple carbohydrates and saturated and trans fats should be reduced, exercise increased, and possibly more sleep (Lamberg 2006). Exercise needs to be enough to increase total energy expenditure to 160–180% of the resting metabolic rate (Erlichman et al. 2002). Increasing exercise with or without a weight loss diet induces a modest weight loss. People with diabetes should have a thorough physical assessment before undertaking exercise and weight loss programs that need to be individualised for best effect. Along with diet, exercise prescriptions (Elfhag et al. 2005) and wearing a pedometer (Richardson et al. 2008) can help the individual achieve weight loss.

Counselling and behavioural strategies that encompass support, exercise and dietary counselling are effective and in Australia are supported through some health benefit funds. For example, commercial diet oriented weight loss programmes such as Step into Life, Mass Attack Weight Loss Program, Lite n’ Easy, ClubOptiSlim. Some of these programs deliver nutritionally balanced portion controlled low fat meals to the individual’s home.

Prepared low-energy meals or meal replacements that replace some or all of the individual’s diet can be useful as an initial weight loss strategy or to avoid refeeding syndrome after severe calorie restriction or bariatric surgery. However, they can be expensive in the long term.

Self-help programmes often combine lifestyle change, computer-assisted interventions, packaged programmes such as Internet correspondence courses, and take home weight loss kits. Self-help programmes are difficult to measure but Latner (2001) claimed 45% of people using such programmes lose weight and keep it off. Knowledgeable clinicians can support individuals likely to benefit from a self-help approach (Tan et al. 2006).

Significantly, public health programmes that involve health providers, legislators, the food industry, and health insurers are needed and must include children and adolescents. Weigh loss strategies may need include strategies to keep people physically active in the longer term and recent research suggests it could be important to minimise exercise variation because maintaining exercise at a consistent level moderates age-related weight gain in proportion to the amount of exercise performed (Williams 2008). Even fit people tend to gain weight with increasing age, thus the amount of exercise may need to be increased to reduce age-related weight gain (Williams 2008). Significantly, stopping exercise leads to weight gain.

Dietary management: diabetes

Diet is the mainstay and first line of treatment of Type 2 diabetes to control blood glucose and manage cardiovascular and other health risks. The aim is to achieve a healthy weight range for the individual. The aim is to achieve an appropriate weight within the healthy weight range for the individual, but focusing on weight might mean the under nutrition is not considered, which as indicated, might confer more health risks than overweight especially in older people.

Expert dietary advice is essential but the changing role of the nurse and the focus on the preventative aspects of healthcare mean that nurses have a responsibility to develop a knowledge of nutrition and its role in preventing disability and disease. A number of basic screening tools can be used to identify dietary intake and nutritional characteristics and can be incorporated into usual nursing assessment and patient care plans and enable useful information to be communicated to the dietitian.

The general dietary principles apply to the whole population as well as all people with diabetes. Precise advice depends on the individual’s age, gender, lifestyle, eating habits, cultural preferences and nutritional requirements. It is important that realistic targets are negotiated with the patient, particularly if weight control is necessary. The goal is to achieve gradual progressive weight loss to reduce weight by 5–10%, which is usually achievable and improves the health profile (Pi-Sunyer 2006).

The effect of medications, fasting for procedures, and gastrointestinal disturbances such as diarrhoea and vomiting, on food absorption and consequently blood glucose levels is an important consideration especially during illness.

Optimal nutritional care is best achieved by collaboration among nurses, other health professionals and the dietitian to decide the most appropriate management regimen. Nurses have the greatest continuous contact with the patient in hospital; consequently they have an invaluable role in nutritional management by:

Example questions to ask when taking a diet history. The questions should be asked sensitively as part of a nutritional assessment.

This information provides the basis from which nursing staff can quickly and effectively refer patients to the dietitian who can support nursing staff by:

• Setting dietary management goals for the individual consistent with their health status, lifestyle and healthcare goals.
  
• Identifying possible nutritional problems. Estimating caloric intake is difficult because people generally underestimate their caloric intake by as much as 50% despite trying to keep accurate food records (Fabricatore 2004) but 3-day food records can be helpful to health professionals and the person with diabetes.
  
• Identifying causes of possible nutritional problems and suggesting strategies to overcome them.
  
• Counselling and educating the patient about how to reduce the risks associated with these problems.
  
• Supporting nursing and medical staff on an ongoing basis to ensure most effective nutritional management is achieved and maintained (Dunning & Hoy 1994).