Christopher Gardner, the author of Food Sense and director of nutrition studies at Stanford, says we have overcomplicated the question of what to eat

Finally, some good news: eating well is more straightforward than you think. “There’s a lot of good science out there, and it mostly agrees,” says Stanford University’s director of nutrition studies and professor of medicine Christopher Gardner from his office in Palo Alto – beaming, bronzed and the picture of health.

In the age of social media and wellness grift, we’ve overcomplicated the question of what to eat, he says.

Ultra-processed foods are displacing traditional diets, warns Prof Kent Buse. Plus letters from Hugo Harper, Dr Pawan Randev and Patricia Hampton

Your editorial on cancers in under-50s (8 October) rightly names food among the culprits. But the confrontation it calls for should be aimed less at obesity than at what produces it. Obesity is the intermediary; the exposure is a food system engineered for profit.

The Lancet’s series on ultra-processed foods showed these products displacing traditional diets worldwide and driving chronic disease, and documented more than 200 interconnected lobby groups through which the industry organises its influence to block regulation.