Diets: Fat

Lord Krebs Excerpts

Thursday 31st October 2024 Grand Committee

[Lord Krebs (CB)]

My Lords, I declare my interests as recorded in the register, in particular my work with the World Cancer Research Fund and the fact that I am a scientific adviser to Marks & Spencer. Like the noble Lord, Lord Brooke of Alverthorpe, I was a member of the Select Committee which reported last week on diet and obesity. I congratulate the noble Lord, Lord McColl of Dulwich, on securing this debate and his introduction to it.

The idea that eating a diet with plenty of fat suppresses appetite is not new. About 50 years ago, Dr Richard Mackarness published a book entitled Eat Fat and Grow Slim. However, like so many other dietary fashions, this one ran into the sands of evidence. I will mention just one study: a double-blind randomised control trial published in the journal Nutrients in 2018. The participants—older, healthy males—were offered one of three calorie-controlled drink supplements containing different amounts of fat, protein and carbohydrate, or a control drink containing virtually no calories. The results showed that adding fat to the supplements raised levels of the gut hormone cholecystokinin, to which the noble Lord, Lord McColl, referred, but did not suppress energy intake from a subsequent buffet meal with ad libitum food. The evidence does not support the idea that eating more fat suppresses appetite.

The National Diet and Nutrition Survey shows that the population-average intake of fat is close to the recommended guideline of 35% of daily energy intake. However, the intake of saturated fat is above the guideline of 11% of daily energy intake. Saturated fat, in particular animal fat rather than fat from dairy produce, is associated with an increased risk of cardiovascular disease and stroke. Therefore, dietary advice is, correctly, to consume less saturated fat, but not because of its contribution to obesity.

Turning to obesity, I will make three points. First, the best way to tackle the obesity crisis is to prevent people putting on excess weight in the first place. This is most effectively achieved, as the noble Lord, Lord McColl, said, by reducing calorie intake rather than by trying to burn it off with exercise—if you try to burn off the calories from one energy drink, you will find out how tough it is.

Secondly, the dramatic rise in obesity during the past 30 years has been driven largely by the increased availability of cheap, highly palatable, calorie-dense food, known colloquially as “junk food”. The report of the Food, Diet and Obesity Committee published last week recommends a raft of policies to deal with this challenge. The overarching theme is that there should be a switch from the 700 or so failed policies based on individual choice to policies based on regulation of the junk food industry and the junk food environment. Does the Minister agree with that general proposition?

Thirdly, it might be tempting to see effective weight-loss drugs such as Wegovy and Ozempic as a “get out of jail free” card. They will have an important role, but they are not the answer to treating the millions of obese people in this country and a much larger number around the world. At the moment they are very expensive, although it is possible, with many drugs in development, that the price will come down. More importantly, they require a lifelong commitment: it is not just about taking the drug for a few weeks; it is about taking it for ever. Recent data from the United States, where one in eight people has tried a weight-loss drug, show that two out of every three obese people give up taking the drug within a year and then regain the weight they have lost.

The Government have said they want to shift from treatment to prevention as one of the three pillars of reforming the NHS. Can the Minister explain to us in broad terms how she envisages this shift from treatment to prevention being applied to diet and obesity, the second-biggest avoidable risk of ill health? In this context, I want to cite one example and ask the Minister to comment on it. My local sports centre, owned by Oxford City Council and which I visit regularly, has an entrance packed with junk food—sugary drinks, ice creams, doughnuts, the lot. Does the Minister think that that is an appropriate way for a local council to run a fitness centre?