Once smoking was the killer health problem in Scotland. Now comes the news from Cancer Research that around 29% of adults in Scotland are obese whereas 18% of the population continues to smoke. In the early 1980s the figures were markedly different, at around 6% and 40% respectively. That means in just four decades the country has gone from one in 16 of the population being obese to a staggering almost one in three.

Such changes have led to major shifts in disease patterns: rates of heart disease have gone down partly due to less smoking, but the prevalence of other diseases, such as diabetes, has risen significantly in the last four decades. Being overweight or obese increases risks for many conditions including chronic lung diseases, liver disease, high blood pressure, skin disorders, joint problems, sleep apnoea (when breathing is interrupted), pregnancy complications and mental health issues.

More worrying is the link between excess body fatness and many cancers, prompting a new Cancer Research campaign to highlight the issue. According to the charity’s analysis of Scotland’s 2017 health survey, excess weight causes around 190 more cases of bowel cancer than smoking in Scotland each year. The same pattern is true of cancer in the kidneys (around 130 more cases caused by excess weight than by smoking), ovaries (around 40) and liver (around 25).

Body fat and cancer

Overall, smoking remains the number one cause of cancers, but the contribution made by excess body fat is continuing to rise, and will become the most important determining factor of cancer in many high-income countries like the UK in future.

What is equally concerning is that while we are getting better at preventing – or not dying from – heart disease and stroke, we know too little about the molecular links between obesity and multiple cancers to have even begun to develop any clever medicines to interrupt this process. For now, the only way to lessen risk of cancers – and many other conditions linked to obesity – is to help people lose weight sustainably.

Of course, many of the facts above are well documented and will come as little surprise. Neither will the rising cost for the NHS of treating obesity-related illnesses, set to reach nearly £10 bn pounds by 2050. So, the million dollar question: what is the main cause for this obesity epidemic?

Is it that we are on average less active than before? Perhaps, but not by nearly enough to account for the rise in average adult weights. Boris Johnson’s recent assertion that physical activity will be the best way to tackle the epidemic has little evidence to support it.

Is it that people are greedier than they were in the 1970s? Many experts would argue not and I agree. Our biology and genes have not changed in the last 40 years or so, and few, if any, people who are obese wish to be so. Being heavy is mentally and physically challenging, affecting self-esteem and the capacity to be active.

That said, people are eating many more calories than they did in the 1970s, even if food surveys often report the opposite. We know this because heavier people burn more calories, so to remain the same weight they must be taking in more – it’s basic physics. And this leads us to the main question: why? The answer is that we are all are more exposed to an abundance of much cheaper, calorie-dense foods full of fats, refined sugars and salt – all the things that stimulate the palate to want more. And many of us cannot resist.

On the upside

There is some good news here. We know how to help people lose weight sustainably with clear evidence that diets work as long as people stick to them. Commercial weight loss programmes also help many, as do small sustainable changes in diet – for example consuming fewer sugary and alcoholic drinks and confectionery in favour of water, diet drinks and more fruit and vegetables.

Slowly, but surely, there is also a realisation within the medical profession that people who are obese need support not shaming. Those who are obese must be encouraged to try different dietary changes and given more directive advice and encouragement.

It’s no longer enough to say to people they need to lose weight. Most know this already, but don’t know how to do it sustainably, so more information must be given. There are also new weight loss drugs on the horizon that may help people shed around 10% of their body weight or more, but of course, these are not without significant costs.

Finally, the sugar tax suggests governments in the UK and several other countries at last recognise the need to alter the food and drink environment. But on its own it will have minimal effect.

The real question is whether the government is prepared to go further and impose regulations on the food industry that really do bite: by making unhealthy foods more expensive and ensuring that healthier options are tasty and good value. Only in this way will we have a chance to make meaningful inroads to population obesity levels, and improve health and well-being across the country.

The Scottish government was among the first to impose the smoking ban, and there is no reason it could not also lead the battle against obesity. It’s not rocket science, but politically and economically, it is extremely challenging.