Obesity: Evidence informing policy

Overview

Weight gain is underpinned by a complex range of social, economic, educational and environmental factors.^1-4 Evidence suggests that strategies targeting individual behaviours relating to diet, energy intake and physical activity without changing the many determinants of these behaviours are unlikely to achieve significant or sustained outcomes.^1-4

A comprehensive, multi-sectorial approach to preventing obesity at the population level in Australia is needed, which includes reshaping the food environment to promote healthy dietary behaviours and supporting participation in regular physical activity.

Multiple levels of action are needed to support people living with overweight and obesity to overcome the barriers to quality care that they face, including a population-wide, evidence-based approach, community-based weight management strategies, specialist services, and the introduction of medicines and services where clinically indicated.⁵

Overarching this is the importance of reducing stigma and the increased risk of mental ill health associated with living with overweight and obesity.⁶

The food environment

Food labelling

Food labels contain both factual information and marketing claims. Food labels provide information on mandatory details such as ingredients, nutritional values and allergen warnings while marketing claims are used to promote the product by emphasising particular health benefits or highlighting a unique product feature.⁷ Surveys indicate that more than 30% of people regularly use labels to inform their decision making on their selection of food products, with up to 80% using them when selecting and purchasing a new product. ⁸ However, many consumers misinterpret the information displayed ^{9, 10} and while food labels provide essential factual information to help consumers make informed choices, the inclusion of marketing claims on the front of packaged products often competes with the factual information that is presented on the back of pack and serves to influence purchasing decisions. ⁷

Front of pack

Front-of-pack interpretive labelling has been shown to be effective in assisting consumers to identify healthier food options at the point of sale, ^11-14 and help guide their selection processes and in doing so may improve health outcomes. Systems with an interpretive element to indicate the healthiness of a product generally perform better in assisting consumers to identify healthier foods.^15-17

Front-of-pack labelling has been shown to be effective for all population subgroups, with people from both low and high socioeconomic status groups more likely to pay attention to front-of-pack labelling as opposed to the Nutrition Information Panel. ¹⁸

There is evidence that front-of-pack food labelling provides an incentive for food manufacturers to increase the availability of healthier products through product reformulation, including reducing sugar, fat and/or salt and increasing fibre in their products. For example, the adoption of the Choices logo in the Netherlands¹⁹, mandatory trans-fat labelling in South Korea, Canada, and the US^20-22, and the Pick the Tick logo in New Zealand²³, led to reformulations that improved the nutrient profile of products in these markets. Current evidence ^{24, 25} has confirmed that while uptake is slow, the implementation of the Health Star Rating system is driving food manufactures to make positive changes to reformulate their products to ensure a more favourable Health Star Rating.

Other influential methods the food industry and companies use on labels are nutrition content and health claims. Nutrition content claims highlight the presence or absence of a nutrient, such as ‘high fibre’ or ‘low fat’. ²⁷ Products carrying these do not need to meet minimum nutrient standards, and therefore food companies use nutrition content claims to highlight positive aspects of products that have negative attributes, such as marketing a high-sugar product as low-fat.²⁸ This is a problem as consumers perceive foods carrying claims as healthier than foods without claims, regardless of their nutrition composition,^{29, 30} and claims drive purchases.³¹ Research in Australia has found that up to 79% of products carrying nutrition content claims in some food categories are not healthy enough to make a health claim.³²

Health claims highlight a food-health benefit, such as ‘contains calcium for strong bones’ or ‘high in fibre for healthy gut bacteria’.²⁷ Products carrying claims must meet the minimum nutrient standards set out in the Nutrient Profiling Scoring Criteria around healthiness.

Food manufacturers can base health claims on either a pre-approved general level health claim or a new claim by conducting a systematic review and notifying Food Standards Australia New Zealand. However, this process has limited effectiveness, with monitoring and enforcement relying on external complaints to generate action on dubious claims that lack evidence.^{33, 34}

Eating food high in added sugars, including sugars and syrups added to food or beverages during preparation and ultra-processed foods, increases overall energy intake while reducing opportunities to eat more nutritious foods, and can lead to weight gain. The Australian Dietary Guidelines advise Australians to limit their intake of foods and drinks containing added sugars. The World Health Organization recommends that free sugars for adults and children should be at most 10% of their daily energy intake.²⁶ However, World Health Organization recommends that a further reduction to below 5% per day would provide additional health benefits. The Food Regulation Standing Committee is considering amending the Australia New Zealand Food Standards Code to include ‘added sugars’ in the nutrition information panel (NIP). This addition will raise awareness about the presence of added sugars in foods.

Food marketing to children

Children in Australia are exposed to a high number of advertisements for unhealthy food on television and through non-broadcast media. Research estimates that the average Australian aged between 5 to 8 years old who watch approximately 80 minutes of television each day is exposed to a minimum of 827 unhealthy food and beverage advertisements, equivalent to four hours, on television each year. ³⁵ Substantial exposure also occurs through digital marketing ^36-42 and packaging promotions.^{36, 38, 43, 44}

These exposures to unhealthy food marketing result in increased consumption of energy dense food by children.^45-47 Reducing children’s exposure to unhealthy food marketing has been identified as one of the most cost-effective strategies to prevent obesity, in part because it has the potential to reach a large population of children, and therefore, is a key area for action.^48-50 Food marketing to children generates positive beliefs about the advertised products, and influences food preferences, purchasing requests and consumption, as well as dietary habits and health status.^51-55  Evidence shows that children do not understand the persuasive intent of food marketing; that food marketing influences children’s food preferences and generates positive beliefs about the foods advertised.⁵³ Further, the high level of unhealthy food advertising may limit the effectiveness of social marketing campaigns promoting healthy foods and lifestyles.⁵⁶

Current food marketing regulations are limited, and only apply to specific children’s programming on television.⁵⁷ The highest numbers of children watch prime time commercial television between 5:30pm and 9:30pm when the regulations do not apply.⁵⁸ Advertising industry codes are in place, but their effectiveness is limited as they are typically voluntary, permissive, and poorly monitored and enforced.^59-63 The Federal Government is currently undertaking a feasibility study on options to limit unhealthy food marketing to children and is supported by the National Preventive Health Strategy 2021-2030, National Obesity Strategy 2022-2032 and the National Diabetes Strategy 2021-2030 which include the common policy goal of restricting unhealthy food marketing to children.

A large proportion of primary school-aged children have their own mobile device (67%) and 1 in 6 have a social media account, amounting an average screen time of 31.5 hours per week. ⁶⁴ With the advancement of digital-based marketing, brands have been able to target and engage users with personalised messaging and infiltrate online communities with brand content. Research shows that children who report higher web-based engagement with food brands and content, particularly in the form of online videos, were more likely to consume unhealthy food and beverages. ⁴⁷

Food reformulation

Many processed foods are high in salt, sugar, fat and energy, making them low in overall nutritional quality. Improving the nutritional quality of the food supply through mandatory product reformulation has enormous potential for improving population nutrition and health.³ Reducing portion sizes of processed foods, which have increased substantially in recent years, also has the potential to decrease energy intake as evidence indicates that people tend to consume more kilojoules when they are presented with larger portions of food and beverages.³

Access and food environment interventions

Access to affordable and nutritious foods is notably more difficult in rural and/or disadvantaged communities.⁶⁵ In remote communities the food supply has been found to be unstable due to factors such as poor infrastructure, and the high costs associated of living and operating stores in remote areas. ⁶⁶ For example, many remote community stores cannot purchase foods at a volume where they could negotiate better wholesale prices, due to the difficult trading environment. ⁶⁶

Food environment interventions can improve dietary quality at the population level by ensuring access to affordable, high-quality food. ⁶⁷ Research has identified product placement and price promotions as influencing factors in food purchasing behaviours. Food retailers can influence consumption patterns through the way they choose to organise, display and promote products. ⁶⁸ Price promotions are more prevalent on unhealthy food products than on healthy foods and beverages. Therefore, food retail designs should promote healthy food environments by prioritising the placement and promotion of healthy foods over unhealthy items. ⁶⁹

In addition to modifying the food environment, enhancing the promotion of existing guidelines which support positive lifestyle change such as the Australian Dietary Guidelines,⁷⁰ Australia’s Physical Activity and Sedentary Behaviour Guidelines,⁷¹ and the 24-Hour Movement Guidelines ⁷¹ is imperative to mitigating risk of cancer and chronic diseases.

Economic interventions

Economic interventions, such as taxation, grants and subsidies can provide incentives and disincentives to help modify health behaviours to improve diet.¹

A systematic review has shown that taxes and subsidies are likely to be effective in improving food consumption patterns contributing to obesity.⁷² Soft drink taxes and healthy food subsidies have been shown to be effective in promoting changes in dietary habits.⁷³ Estimates have indicated that a 10% tax on unhealthy food and beverages would result in a 6% reduction in consumption of these products.⁷⁴

An Australian study examined the cost-effectiveness of combining taxes on unhealthy foods and subsidies on healthy foods. The combination of the taxes and subsidies could avoid the loss of as many as 470,000 disability-adjusted life years in the Australian population, at a net cost-saving of AU$3.4 billion to the health sector. ⁷⁵The largest gains in health were achieved by a sugar tax. A fruit and vegetable subsidy is cost-effective when added to a package of taxes.^{75, 76}

Fresh and frozen fruit and vegetables and some other basic food items are not subject to the goods and services tax (GST) in Australia, and this has been identified as an area where Australia is meeting global best practice benchmarks. It is important that this exemption is maintained. There are opportunities for government to further subsidise healthy food options, increasing their affordability, particularly in remote communities where fresh produce can cost up to 30% more than in urban areas.⁷⁷ Cancer Council welcomes the announcement from government on their decision to lock the cost of 30 essential items in select remote stores, to ensure they are in line with the prices seen in metro stores. ⁷⁸Incorporating subsidies into the design of food taxes could support those on low incomes to combat the impact of a tax on unhealthy foods and may result in higher consumption of healthier foods, such as fruit and vegetables. ⁷⁶

Public education

Evidence increasingly shows that well designed and executed social marketing campaigns on health issues that are sustained over time can be effective in changing health knowledge, beliefs, attitudes and behaviours across large populations.^{56, 79, 80} While the bulk of current evidence relates to tobacco control, social marketing interventions have also been shown to be effective in increasing physical activity and improving nutrition.^{56, 81-84}

Social marketing interventions are more effective when they are one component of a comprehensive approach targeting population health behaviours. The outcomes of these interventions are also generally better when supported by complementary policies and programs and competing marketing messages are restricted. ⁸⁵ For example, the The LiveLighter® public education campaign to address overweight and obesity includes mass media, advocacy initiatives and education and support tools.

Treatment and management options

Nutrition

Measures to improve dietary behaviours alone or in combination with other lifestyle interventions are commonly used for the management and treatment of overweight and obesity.⁸⁶ There are a range of dietary strategies that promote a healthy way of eating and can assist with achieving and sustaining a reduction in total energy intake.⁸⁷

Given the complexity in treating and managing overweight and obesity as a multifactorial and chronic condition, adherence to any diet-based intervention is to be delivered with the support and advice of medical and allied health professionals.⁸⁸ Ongoing follow up is required to evaluate patient outcomes and to further adapt individualised goals and interventions as the treatment progresses. ⁸⁸

It is important to acknowledge that the ability in which individuals can engage in healthy eating behaviours is influenced by a complex range of factors which encompass societal and individual levels. Empowering all Australians to pursue healthy diets warrants addressing these multifactorial determinants.⁸⁹ Specifically, the underlying structural drivers such as the food environment and conditions of daily living as well as the many intrapersonal factors which contribute to inequities in healthy eating. ⁸⁹

Physical activity interventions

Short-term aerobic exercise of at least a moderate intensity has been found to provide significant improvements in whole-body fat mass, regardless of changes to overall body weight.^{90, 91} Aerobic exercise, as well as aerobic exercise which has been combined with strength training is found to reduce the BMI z-score in children and adolescents who have overweight or obesity.

Peer interventions have demonstrated effectiveness in obesity treatment including reduced body weight and waist circumference in typically hard to engage groups, by providing solutions targeted to the needs of a specific group.⁹² Such interventions have proven efficacious in the school setting and workplace setting. ^{93, 94}Commercial group programs and couples-based therapy have also demonstrated positive impacts on obesity management in adults.^{95, 96}

Behavioural therapy

Behavioural treatment strategies aim to assist individuals to overcome barriers and modify behaviours that may be contributing to overweight or obesity.⁹⁷ Incorporating behavioural change strategies into lifestyle interventions can increase an individual’s adherence to interventions programs and sustain long-term changes.⁹⁷ Behavioural treatment is an umbrella term that incorporates a variety of strategies including self-monitoring, stimulus control, motivational interviewing, behavioural contracting and goal setting, among others.^{93, 97}

There is rising interest in e-health interventions to promote self-monitoring and lifestyle intervention adherence for obesity management.⁹⁸ Apps could provide an accessible, cost-effective intervention, utilising a user’s personal preferences and motivations to individualise interventions.⁹⁸ Emerging evidence on the effectiveness of these e-health interventions in promoting health obesity-related behaviours for children and adolescents is promising.⁹⁹

Medicines

There is significant evidence to support pharmaceutical therapies in the treatment and management of obesity, when used in conjunction with lifestyle interventions including appropriate nutrition and physical activity.^100-103 In Australia there are currently six agents which are approved by the Therapeutic Goods Administration (TGA) for those with obesity, or those with overweight in conjunction with at least one weight-related comorbidity.¹⁰⁴ These agents are orlistat, phentermine, naltrexone/bupropion, liraglutide, semaglutide and tirzepatide.¹⁰⁴

These medications have been found to effect clinically significant weight loss in those with obesity, which is generally agreed to be a 5-10% reduction in weight.¹⁰⁵ Cessation of these medications drug typically leads to weight regain and metabolic reversal, though tapering and rigorous lifestyle adherence may slow this process.

For those who are prescribed semaglutide and not able to access it, or for those with contraindications preventing them from using the drug, an alternative must be used, meaning that people must pay out-of-pocket to access medication. These medications are not PBS listed for the treatment of obesity and can cost hundreds of dollars per month, inhibiting many people from accessing the best available treatments.^{102, 104, 106}

Surgery

Bariatric surgery is the most effective approach to weight reduction in obesity treatment and management, with beneficial effects on cardiometabolic biomarkers, appetite-modulating hormones and improved survival.^100-103

In Australia, the most commonly performed bariatric surgeries include laparoscopic sleeve gastrectomy (LSG), laparoscopic Roux-en-Y gastric bypass (LRYGB) and laparoscopic-adjustable gastric banding (LAGB).¹⁰⁰ Both LSG and LRYGB have demonstrated an excess weight loss of over 50% at one-year follow up.¹⁰⁰ Despite large prospective studies reporting long term improvements in mortality, emerging real-world evidence shows that weight regain necessitating revisional bariatric surgery is far greater than initially reported, and may be up to 50% by the fifth-year follow-up.¹⁰⁵ The long-term success of bariatric surgery must be supported by ongoing lifestyle interventions which promote weight loss maintenance and address potential complications following surgery, including nutritional deficiencies and loss of bone mass.^{100, 107}

In the private sector of the Australian healthcare system, bariatric surgery and post-surgical care is subsidised by Medicare, however the rebate is low. More than 90% of bariatric surgeries occur in private hospitals and incur significant out-of-pocket expenses, often resulting in limited access for individuals urgently requiring the surgery.

Barriers to Care

System level barriers

Overweight and obesity are significantly impacted by a range of determinants including social, environmental and commercial determinants of health.⁸⁹ This diversity of factors that can create inequities are often overlooked in the development of care pathways and clinical guidelines for the treatment and management of overweight and obesity.⁶ Children, older people, Aboriginal and Torres Strait Islander peoples, people with disability and people living in rural and remo

te areas are the most impacted by the inadequate supports available for the management of overweight and obesity.^{6, 108, 109} Additional complexity in recommended care is realised when people must access numerous services across the primary, secondary and tertiary care sectors without appropriate care coordination.⁶ To reduce the complexity, specialised obesity management services have been found to be beneficial to the individual and in reducing the burden on acute healthcare services. ¹¹⁰

Service level barriers

In addition to these system-level barriers to optimal treatment and management, there are service-level barriers, whereby healthcare professionals report not feeling confident in delivering treatment and management interventions.¹¹¹ While many are motivated to incorporate this as a standard part of their role, limited training in raising the topic of weight with patients, as well as a lack of appropriate referral pathways are cited as common barriers.^{111, 112} This is further perpetuated by outdated guidelines which do not consider the current evidence on emerging interventions, technologies and treatments.^{111, 112} To facilitate improved care for people with overweight and obesity, focus must be placed on creating living guidelines, which take into consideration the rapid advances that are made in treatment and management options as well as adequate training and capacity for GPs and Aboriginal Community Controlled Health Organisations.⁶

Aboriginal and Torres Strait Islander peoples and other Indigenous peoples experience higher rates of obesity and related comorbidities; although these groups have a significantly lower rate of intervention when compared to non-Indigenous people.^113-117 This inequity is multifactorial, including geographic challenges associated with accessing appropriate care, systemic racism in Western healthcare systems and cultural concerns which have not been appropriately considered or addressed.¹¹⁸

Stigma

Weight stigma has a significant impact on people’s health behaviours and affects access to health services.^{119, 120} This stigma can arise from many different sources including interpersonal interactions, media outlets, educational materials, and perceived social norms.^120-125 Negative comments, and derogatory language have been described as the most common forms of weight discrimination.^{121, 122} Further, individuals who have overweight and obesity have expressed perceptions of societal attitudes of laziness and assumed personal responsibility.^{121, 122}

The pervasive nature of weight stigma, when perpetrated by healthcare professionals, impacts the adequacy of care that people with overweight and obesity receive, and contributes to a profound reluctance to seek ongoing care.¹²⁴ Individuals have described feeling misunderstood when interacting with primary health care providers, and expressed concerns that there is a lack of knowledge on how best to manage or treat overweight and obesity.¹²¹

Mental health

Overweight and obesity are associated with depression, anxiety, lower self-esteem and poor body image.^126-129 In turn, these symptoms can have a negative impact on weight loss outcomes.¹²⁸ Evidence demonstrates that participation in obesity treatment, either under the supervision of health care professionals or a structured program, can reduce depression and anxiety symptoms and improve body image and quality of life,^{127, 130, 131} and these effects may be a direct result of the weight loss participants have experienced. Further, dietary interventions have been found to have a positive effect on depressive symptoms, ^{132, 133} and some dietary interventions may prevent depression.¹³² However, perceived weight stigma has been significantly associated with diminished mental health, with a stronger association demonstrated with increasing BMI.

Determinants of health, including culture and location, play an important role in mental health and obesity management.¹³⁴ Aboriginal and Torres Strait Islander peoples are more likely to experience both overweight and obesity and mental ill health compared to non-Indigenous people.¹³⁵ People residing in rural and remote areas are more likely to experience severe obesity and poorer mental health than people residing in metropolitan areas.¹³⁴ For children and adults, interventions with a physical activity component have been demonstrated to be particularly beneficial for improving psychological symptoms.^{136 137}

The identification of depression, anxiety and eating disorders through simple screening questions and subsequent referral to appropriate mental health support should be performed by medical and allied health professionals as these conditions are common co-occurrences among people with obesity engaging in intentional weight loss. ¹³⁸