People who cook minimally processed meals at home lose more weight than if they eat ready-made, ultra-processed meals – even if these foods are healthy, a new UK study has found.

Food experts have long pointed to ultra-processed foods as a key driver of the obesity crisis, which affects about one in eight people worldwide.

These foods are often high in saturated fats, sugar, and salt, for example crisps, frozen dinners, and processed meats. But they also include staples like wholemeal sliced bread and baked beans, meaning ultra-processed foods are not always unhealthy.

That’s prompted much debate over whether it’s the ingredients or the processing itself that really matters when it comes to our health.

The latest study, published in the journal Nature Medicine, indicates that minimally processed diets are better for weight loss – but that diets rich in ultra-processed foods can still be healthy as long as they meet nutritional guidelines.