In principle, the major causes of global disability and reduced life expectancy have always been preventable. Through research and its translation into public health policy, the 19th and 20th centuries largely overcame the historically dominant preventable causes – infections and malnutrition, with the notable exception of death and disability due to gun ownership and armed conflict.
In current times, the major preventable causes of disability and reduced life expectancy are tobacco and overweight/obesity. Both are consequences of the commercial exploitation of powerful physiological human appetites for nicotine, food and drink, supported by successful marketing that presents smoking and overconsumption as normal or desirable. Smoking has declined in higher-income countries, partly through health awareness and policy, and partly through younger people rejecting their exploitation for profit by tobacco companies. Sadly, investors still support tobacco companies as activity is transferred to low- and middle-income countries, where the full health impacts of smoking have yet to be felt.
In current times, the major preventable causes of disability and reduced life expectancy are tobacco and overweight/obesity.
While most smoking-related disease takes four or five decades to develop, many health consequences of overweight/obesity appear at a younger age, especially among Asians, who make up a quarter of the global population. Accepting wide individual variations, its physical and mental symptoms and disabilities become problematic after the age of 30-40 and potentially devastating cardio-metabolic complications become apparent from the age of 40-50. Among these, type 2 diabetes is by far the most critical. It has become the most common cause of blindness, lower-limb amputation and kidney failure, and a significant contributor to heart failure. Type 2 diabetes reduces life expectancy similarly to some major cancers, but it affects many more people – the overwhelming majority of the 537 million people currently estimated to be living with diabetes across the world. Driven by genes, age and weight gain, up to 50% of all people will develop type 2 diabetes if excess body fat accumulates in vital organs, particularly the liver and the pancreas.
Consistent evidence shows that type 2 diabetes can be prevented by relatively modest intentional weight loss. Once established, the condition can be reversed into remission, for a 1–2-year period at least, with weight loss of about 10 kg that removes abnormal fat from the liver and pancreas, allowing organ functions to recover. Type 2 diabetes is therefore part of the underlying disease-process of obesity.
Most people do not overeat and become overweight on purpose. The disease process emerges when, with relatively low levels of physical activity, appetite no longer matches energy expenditure. When there is an excess of available food without the need for physical activity, the accumulation of body fat is an advantageous evolutionary response to store calories for a future period of food scarcity. Therefore, most human appetites are set a little higher than needed for steady body weight. This physiology has presented a commercial opportunity.
Up to 50% of all people will develop type 2 diabetes if excess body fat accumulates in vital organs, particularly the liver and the pancreas.
Over the past 40 years, the average Body Mass Index (BMI) of adults in western populations has risen from about 24kg/m2 to 28kg/m2, representing an average weight increase of around 8-10kg. To avoid losing this extra weight, increasingly inactive populations must consume about 100-120kcal more every day. Increased food and drink sales to achieve and maintain our higher BMIs have coincided with falling food costs and societal changes towards eating processed foods and drinks in new settings. Snacking and low-cost catering sectors, both utilising sophisticated marketing techniques, have normalised eating as a social activity outside the home. These foods are aggressively marketed for their added-value for sellers, not consumers. They have low nutritional content, and some contain added addictive ingredients, such as caffeine, to increase sales.
Against this background, with a very wealthy and cynical, ‘big food’ industry neglecting the collateral damage to health caused by overconsumption, conventional health education and projects aimed at preventing obesity have essentially failed. No country has seen a decline in the prevalence of obesity, and the upward trend continues in many countries. Well-meaning education-based projects in schools and other settings have generated modest short-lived reductions in average weight gain. However, these interventions may preferentially impact children of normal weight with existing healthy behaviours, rather than those destined to become obese adults. Home, family and social settings are more important than education for determining health behaviours.
It makes sense to tackle obesity among young people, where prevention would have the greatest benefit. However, attempts to influence young people to lead their lives differently usually fail. Young people customarily react against authority and are considered ‘hard-to-reach’ or unresponsive to health education. Yet, herein lies most potent weapon to tackle obesity – the strength and stubbornness of young people to defend causes they find important. This provides a novel 21st century solution to the dual epidemics of overweight/obesity and type 2 diabetes. Young people have always been central in social movements for the common good, with their ability to mobilise collective support for action on causes that concern them. Examples include their leading roles in campaigns for human rights and tackling the global environmental crisis. Assisted greatly by social media, these social movements often arise spontaneously, but require several layers of organisation to be effective (see figure 1).
Young people have the will and power to protect themselves from exploitation. The recent rejections of smoking and, to some extent, alcohol by youth reflect awareness and rejection of exploitation by ‘big industry’. The same principle could generate a social movement against the exploitation of youth by sectors of the food industry which encourage overconsumption, particularly of processed foods, driving people away from traditional dietary habits. Young people are increasingly turning to vegetarianism or veganism on humanitarian and environmental grounds.
Type 2 diabetes can only be prevented by avoiding the accumulation of excess body fat and becoming overweight. Nurturing a global social movement among young people to celebrate, and create demand for low-profit-margin, low energy-density traditional foods that are also animal and environment-friendly (Figure 1), might be more effective and cost-effective than ongoing and often futile attempts to change behaviours by education or persuasion.
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