LONDON — Britain is fat, unacceptably fat — fatter than ever before. There is no escaping this development. Turn on the radio and chances are some new report on obesity will be the subject of debate, with handwringing over the “Americanization” of Britain, and hectoring BBC-style questioning as to what can be done.

A recent report in the Lancet medical journal found that 67 percent of men and 57 percent of women in the United Kingdom are either overweight or obese. This put Britain at the top of the supersized league table among big European countries (the likes of Malta and Iceland outdid it). More than a quarter of children are overweight or obese.

The causes are scarcely different from elsewhere in a fattening world: cheap availability of calorie-dense food (burgers, fries, chips, sodas); “food deserts” in poor areas where healthy fare is hard to find and expensive; sedentary lives spent seated in front of the computer or sprawled on the couch with “Game of Thrones” blaring; too much sugar, fat and fructose; broken or weakened families where children forage in the fridge for prepared meals and snack all day rather than gathering for a family meal; speeded-up societies that breed bored, stressed, impulsive and compulsive behavior, including binge eating and constant eating.

As Tony Goldstone, a consultant endocrinologist at London’s Hammersmith Hospital put it to me: “In the developed world we don’t eat because we are hungry.” We eat because everywhere we look there’s a superabundance of food and we’re hardwired through evolution to keep our body weight up.

The effects, as elsewhere, include a sharp increase in diabetes. Since 1996 the number of people diagnosed with diabetes in Britain has more than doubled to about three million. It is estimated that by 2025 there will be some five million diabetics. Direct and indirect health costs related to spreading obesity range into the billions of dollars.

The new social divide sees the skinny affluent at their Knightsbridge gym raving about their personal trainer and favorite farmers’ market, and the pot-bellied poor guzzling kebabs and fries. The counterintuitive association of poverty and obesity is an indicator of how much the world has changed. Survival is still an instinct but it is no longer an issue. More people today are overweight than malnourished.

Goldstone said he comes away from obesity conferences feeling gloomy. Telling fat people to get thin through dieting is, he suggests, like “telling an asthmatic to breathe more.” Cognitive control cedes to the force of instinct. “Who says that the will can overcome biology when biology trained us to get food when scarce?” Goldstone said. “We evolved to prefer foods high in fat and sugar because they contain the calories we need to reproduce.”

Our urges are out of sync with our environment. The environment has changed. Urges have not. Our instinct is to eat and rest. We have no instinct to stop eating and be active. We eat to survive and then want to rest because we may need energy to flee some wild beast. Once we’ve found our lunch, our instinct is to avoid being someone else’s.

It may not seem like lying on a couch is part of our survival gene but it is. David Haslam, the chairman of Britain’s National Obesity Forum, told me: “It is in our interest to eat and be lazy. Put people in an environment like the current one that promotes eating and laziness and they will oblige.” It’s their genetic inclination.

So I’m gloomy too. I eat more in the hours before I have to write a column. My instinct is then to rest. I cannot because I have to write. My impulse is then to eat again as a way, for a moment, not to write. This only augments the desire to rest. If deadlines did not exist I’d be enormous. Everyone these days plays such mental games, their instincts and environment at war with each other.

This does not mean there is nothing to be done about fat Britain or fat America. Exercise can be encouraged in big and small ways (promoting use of bikes, making sure hotels no longer hide the stairs). Make restaurant chains post calorie information. Improve labeling (Goldstone, a diabetic, told me he often can’t work out from current labels how many carbohydrates a product contains). Oblige supermarkets to move sweets from the checkouts, as Tesco has agreed to do. Get healthy food into schools and poor areas. Haslam told me about an experiment at a Morrisons supermarket where cardboard avatars of a diabetes consultant, a midwife or a doctor pointed to healthy foods. The results were positive. And, for those who can afford it, there’s bariatric surgery.

Nonetheless, the world will get fatter for the foreseeable future because humans in their ingenuity have created a near-perfect environment for the propagation of fatness.