Managing and Preventing Obesity

Behavioural Factors and Dietary Interventions

Timothy Gill

• Publisher: Woodhead Publishing
• Year: 2014
• ISBN:
  9781782420996
• Topic: Technology & Engineering
• Subtopic: Food Science
• Index: Technology & Engineering

Obesity is an increasing problem on a global scale, and strategies for its prevention involve experts from many disciplines including nutritionists, physicians, policy-makers and public health professionals. This book covers the latest advances in obesity development, management and prevention with specific focus on dietary interventions. Part one covers the development of obesity and key drivers for its continuation and increase. Part two looks at the role of specific dietary components in obesity management, and part three discusses the role of behavioural factors such as eating patterns in managing and preventing obesity. Part four focuses on structured dietary interventions for obesity treatment, and part five looks at public interventions and consumer issues.

• Reviews how different foods and diets can affect obesity management
• Examines various ways of preventing and treating obesity
• Explores how governments and industries are preventing and treating obesity

Part One

General issues

1

Trends in understanding patterns of obesity and health outcomes

W.P.T. James¹; R. Jackson-Leach^{2 1} London School of Hygiene and Tropical Medicine and World Obesity Federation, London, UK
² World Obesity Federation, London, UK

1.1 Introduction

Although obesity has been described in literature and depicted in paintings for many centuries it is very clear that excessive weight gain in adulthood on a population level is of recent origin and really became of medical and public health concern only in the late 1970s. At that stage the crude definitions of overweight and obesity set out as the body mass index (BMI) were derived from mortality data taken from the pre-Second World War U.S.A.-based Metropolitan Life insurance statistics. BMIs of 25 and 30 are still taken for the clinical and epidemiological classification cutoffs of overweight and obesity in adults despite suggestions to the contrary from Flegal (Flegal et al., 2007, 2013). Her analyses are based, however, on relatively short term US studies which were known since the 1970s as not being a suitable basis for demonstrating the incremental effect of modest increases in BMI; they also fail to take account adequately of several other major issues including the effect of smoking and unintentional weight loss associated with pre-existing disease. A series of integrated cohort studies involving well over a million subjects with long follow up periods from across the globe has confirmed the value of BMI 25 as a reasonable limit in terms of all-cause mortality and ischaemic heart disease mortality rates (Batty et al., 2006; Prospective Studies Collaboration 2009; Adams et al., 2006) with only death rates from haemorrhagic strokes suggesting that a higher BMI, e.g. of 30, might be more reasonable (Asia Pacific Cohort Studies Collaboration, 2004). Indeed the 57 prospective studies analyses with nearly a million subjects found that in both sexes mortality was lowest at about 22.5–25 kg/m and each 5 kg/m² higher BMI was associated with about a 30% higher overall mortality. As usual the first three years of follow up had to be discarded because those who were already ill had lower BMIs and early deaths so without this adjustment the curves were J shaped. These data have recently been amplified with data from 97 cohort studies demonstrating clearly that overweight (BMI 25–29.9) as well as obesity is a predictor of both coronary artery disease and stroke in Caucasians and Asians, with only 50% of the excess risk being attributable to changes in the classic risk factors of blood pressure, cholesterol and glucose (Lu et al., 2014).

It is clear that BMI is only a crude predictor because the presence of co-morbidities such as hypertension and diabetes are far more powerfully predictive of an early death than BMI alone, probably because they reflect ongoing processes of cellular and organ damage (Padwal et al., 2011). The Asian criteria of a lower BMI of 23 were not based on mortality data at all but on the accepted greater morbidity of many Asian groups as weight increases, albeit that in Caucasians it has also been known for decades that the co-morbidities of diabetes, hypertension, coronary heart disease and some cancers increase progressively from a BMI of about 20. Nevertheless, internationally adult overweight and obesity continue to be considered in terms of the World Health Organization (WHO) accepted BMIs of 25 and 30.

1.2 The importance of abdominal obesity

It has been known for decades that the distribution of body fat is associated with different levels of co-morbidity and a specific emphasis on fat accumulation in the abdomen was made by Vague in the early post second world war years (Vague 1956). Since then global studies have confirmed the greater sensitivity of measures of waist circumference or waist/ hip ratios in predicting cardiovascular events (Yusuf et al., 2005). Waist/height ratios (W/HtR) have also been advocated (Ashwell et al., 2012) and found to be applicable in children as well as adults with some suggestion that it might be superior to waist or waist/hip ratios alone. Other systematic analyses emphasise the value of adding waist measures to BMI in evaluating the risk of disease or mortality (Carmienke et al., 2013) and in Asian subjects the use of both waist and W/HtR has been proposed for predicting risk (Wakabayashi 2013). There seems general agreement that waist measurement is a better measure than BMI and the simplicity of the waist measure is easy for both the public and professionals to understand and certainly overcomes the need to measure the hip circumference, which in some societies is a culturally problematic measure to make except with female physicians taking considerable care. The original Scottish SIGN guideline and the subsequent WHO choices of waist circumference measurements (WHO 2000) were made simply on the basis that the waist measures chosen would correspond with the BMI cut-offs for overweight and obesity, i.e. 25 and 30. Then the International Diabetes Federation proposed other levels of waist measurement for different ethnic groups but based on very different and non-standardized criteria (Zimmet et al., 2005).

Waist values do not automatically increase in line with BMI increases: strong genetic factors influence fat distribution but smoking and alcohol consumption also amplify the propensity to abdominal obesity. Early nutritional and other handicaps, often inferred from evidence of low birth weights, are also associated with later abdominal obesity when even modest weight i...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright page
• List of contributors
• Woodhead Publishing Series in Food Science, Technology and Nutrition
• Preface
• Introduction: an overview of the key drivers of obesity and their influence on diet
• Part One: General issues
• Part Two: The role of different dietary components in obesity management
• Part Three: The role of eating patterns and other behavioural factors in obesity management
• Part Four: Structured dietary interventions in the treatment of obesity
• Part Five: Government and industry interventions in the prevention of obesity
• Index