Obesity and undernourishment kill millions of people every year. But when it comes to food and health, one big risk is often overlooked. Roughly 4m people die annually from toxic fumes produced while cooking, around the same number as those who die from obesity. In much of the world, families still use solid fuels (such as wood or charcoal) instead of cleaner methods (gas or electricity) to prepare their meals. It is the third-biggest cause of early mortality for women and children, after heart disease and strokes.

Unsurprisingly, people in poor countries suffer the most. North Koreans face the highest mortality rates from indoor air pollution. Since 2010 China, India and Indonesia have each halved the number of their citizens who lack access to clean cooking, but progress in Africa has been undermined by its rapid population growth. As countries grapple with how best to ensure their populations are properly fed, it’s important to remember that the challenges extend far beyond the waistline.