What causes a famine? It isn’t a lack of food. Nor does lack of food cause the kind of food insecurity, just short of a famine, that Britain is facing. In analyses of specific famines, the economist and philosopher Amartya Sen showed that social organisation and a lack of access to food for socially deprived people were the real causes of starvation. As 2023 ends, Britain may not be facing a famine, as people are in north-eastern Nigeria, South Sudan, Yemen or Somalia, but that is a low bar. The UK’s current levels of food insecurity will damage physical and mental health and increase health inequalities for years to come. The Food Foundation tracks moderate or severe food insecurity in the UK, which is defined as how many people in the past month had smaller meals or skipped meals; had been hungry but not eaten; or had not eaten for a whole day – each because of lack of access or inability to afford food. In June 2023, the latest tracker, 9 million adults in the UK, 17% of households, experienced moderate or severe food insecurity (a massive rise from 7.3% in June 2021). Nearly a quarter of households with children experienced food insecurity. How will this widespread food poverty affect people’s health? Recent research has shown an alarming increase in admissions to hospital resulting from deficient intakes of micronutrients. And whereas lack of money (among individuals or groups) may lead to starvation in countries threatened by famine, moderate or severe food insecurity in Britain is associated with obesity. There is now fairly general agreement that a Mediterranean-style diet – rich in fruit and vegetables, olive oil, seeds and nuts, with modest intake of fish, meat and dairy – is good for health. But as is now well recognised, energy-dense food, high in fat, sugar (and salt), is cheaper. The inevitable result is that inequalities in childhood obesity are increasing. Obesity is linked to cancer, diabetes, high blood pressure, heart disease and arthritis. Crucially, food insecurity is also linked to more general economic insecurity. There is an important debate going on between those in government who think the way to combat obesity is information about healthy eating, and those who want more activist approaches such as restricting promotions of cheap calorie-dense foods, and advertising aimed at children. But fundamentally, people aren’t eating healthily, in part, because they cannot afford healthy food. Unicef’s latest “report card”, which examined changes in relative child poverty between 2012 and 2021, found that the UK was the worst performer among 39 high-income countries. Our rates of relative child poverty had increased by nearly 20%. The government likes to claim that it has reduced absolute child poverty. It should be careful in making such claims. A recent report from the Joseph Rowntree Foundation defined destitution as doing without two or more of: housing, light, heat, food, appropriate clothing or toiletries. In 2022, 1 million children in the UK were in a state of destitution – 2.9 times the level five years earlier. Among adults, 2.8 million were in destitution because of inability to afford these six basics. Such destitution will damage physical health, not only because of food insecurity, but because poor quality housing and cold homes are also potent contributors. Such insecurity will also damage the mental health of adults and children. The Unicef report shows clearly that the more time children spend in poverty, the more likely they are to experience depression as teenagers, as well as having increased risk of obesity. Returning to Amartya Sen’s diagnosis of famines, the UK has the resources to provide all six of the basics that would eradicate destitution. We don’t do it. It means that large proportions of the population lack the basic necessities of life, and experience the profound insecurity this leaves in its wake. It is hard to see this as anything other than a fundamental, catastrophic failure. Michael Marmot is professor of epidemiology at University College London, director of the UCL Institute of Health Equity, and past president of the World Medical Association