Obesity has been on the rise for some 40 years and will continue to create an enormous burden on global health systems if governments around the world do not take decisive, policy-driven action, according to a new series of papers published in The Lancet.
The papers state the case for action on obesity, describing the size and nature of the problem, the key drivers of obesity globally, and the actions needed to reverse the epidemic.
These insights come at a crucial time, ahead of the first ever United Nations High-Level Meeting on Non-Communicable Diseases, where the global rise of obesity will be discussed as the toughest challenge facing United Nations member states.
The growth and drivers of obesity
Obesity is increasing in all countries, but rates vary widely. In Australia, around one in four adult women are obese, compared with only one in 20 in Japan and China, one in ten in the Netherlands, one in three in the United States, and a staggering seven in ten in Tonga.
In high-income countries, the obesity epidemic seems to have begun in the 1970s and 1980s. Prior to this (in the first half of the 20th century), the population was exercising less because of increased mechanisation and motorisation, but people were also eating correspondingly less, and that kept the obesity prevalence low.
The flipping point seems to have occurred in the 1970s when the still very sedentary population started eating more due to the “push effect” of more readily available, cheaper, high-calorie foods.
Obesity is now sweeping through low-income and middle-income countries, impeding their development and leaving many with a double burden of obesity-related chronic disease in some people and undernutrition in others.
The increased supply of cheap, tasty, energy-dense food, improved food distribution and marketing, alongside strong economic forces driving consumption and growth are key drivers of the obesity epidemic.
The built environment also has an impact – it can blunt or heighten the effects of these drivers. In the Netherlands, for instance, a culture of cycling means obesity prevalence is rising slower than in the highly car-use-intensive United States.
Epigenetic factors (environmental factors that affect gene expression) are a key area of current research that may shed light on the high variability in obesity rates between individuals.
It may seem evident that individual choices are a key driver of whether someone becomes overweight, but in making choices people have to negotiate a highly complex environment, and many decisions are subconscious and outside individual awareness.
What’s more, the food industry is becoming ever more effective at promoting products so people are consuming excess energy without even realising it, so called “passive over-consumption”.
One of the papers in the series highlights how, for decades, a high proportion of doctors and dietitians worked to an incorrect assumption that cutting 2100 kilojoules (about 500 calories) of energy intake every day will result in steady weight loss of about half a kilogram a week.
This assumption ignores changes in the body’s metabolism and leads to unrealistic expectations for diet plans so a more realistic and accurate weight loss predictive model is presented.
It indicates that the weight lost from a given change in diet is likely to be much less than commonly thought and that it takes more than three years to see the full effects of a change in diet.
Policies for positive outcomes
While researchers believe support for individuals to counteract obesogenic environments will continue to be important, the priority should be for policies to reverse the obesogenic nature of these environments.
Other papers in the series indicate the obesity problem will not be solved without strong government leadership, investment and policy intervention.
A summary of the evidence shows some government interventions, such as restrictions on the marketing of unhealthy food and drinks to children and taxes on unhealthy foods (such as soft drinks), are likely to be cost-saving – that is, they are likely to save governments money in the long term through reduced health costs.
A more systems-based approach is needed so greater investments should be made in the core, structural support systems for obesity prevention, such as monitoring population weight and nutrition, workforce development, and integrating health outcomes into all public policies.
Food industry policies also have a very important role with the need to move product formulation towards healthier compositions.
But research notes that the continuing lobbying against possible regulation by the powerful food industry, as well as the public’s own reluctance to let go of things they are used to (such as car access, cheap parking, and access to tasty but unhealthy foods), is hampering public health efforts.
The authors of The Lancet series argue that, even though there are many benefits to current government policies that promote economic growth and free trade, they are contributing to the global crises of overconsumption, including both obesity and climate change.
They say a new framework that promotes prosperity in a broadly defined way, including economic, social, health, and environmental aspects is needed.
The United Nations High-Level Meeting on Non-Communicable Diseases in September provides a key opportunity to strengthen international leadership on this issue.
The United Nations is calling for heads of state to make this meeting a priority, and the authors of The Lancet series indicate that this is an opportunity for governments to take the lead in this area.
Beyond the UN meeting, the test will be how well nations match their declarations with funding and policies to support global action.