Advice against eating fat was wrong. It is time the experts admitted it

    31 May 2016

    Last week the newspapers had a field day — it was the battle of the diet guidelines. A breakaway group of health professionals calling themselves the Public Health Collaboration (PHC) had dared to pick apart and criticise the government’s Eat Well guidelines and produced their own alternative healthy eating guidelines. The medical and governmental establishment — mainly responding to the sensationalist press headlines — retaliated and created their own headlines. Who were these usurpers? Was it not responsible to say to the poor old public: ‘Calories don’t matter and eat as much fat as you want!’ What qualifications did they have and what shadowy agenda and backers? Why didn’t they have more references for their claims? There were personal attacks and claims of foul play by groups who claimed they had not been consulted.

    The headlines generated their own story. Few people probably read the PHC new guidelines or the full Eat Well report from the government they were trying to replace. It became a battle of fat vs sugar. Both sides picked on the dodgy science of the other, there was no compromise and there were no winners except the media. The establishment, although critical of the low-carb approach of the newcomers, believed that attack was the best form of defence and didn’t bother to scientifically defend their clearly out of date guidelines — which recommend, for example, that we avoid saturated fats (which means dairy, nuts and olive oil) and that we eat more starchy carbs (rice and pasta).

    The low-fat guidelines have been largely inherited from the US. Early studies from the 1970s were based upon correlations between death in different countries and the types of food eaten, and these studies were taken as gospel truth by government diet experts around the world. Recently all of these early studies have been re-analysed and found to be fundamentally biased as well as misleading.

    About one per cent of the population have a genetic mutation which means they can’t effectively process fats in their diet and do well to avoid high-fat foods; for the rest of us, however, low-fat diets offer no proven long-term benefits and new evidence in fact shows they may actually be harmful.

    For many years fat was the perfect enemy for governments providing a simple public health message and the food industry was happy to go along with it since it benefited financially from low-fat alternatives with added chemicals and cheap protein from soy. But most ‘real’ food is made up of a wide variety of different fats and, if not consumed excessively, may actually be good for us.

    The real test of whether fats are good or bad doesn’t come from studies on lab mice or blood samples from humans over a few weeks, or even very large observational population studies. The real test comes from large clinical trials following people for years. There are sadly very few of them, but the Spanish government funded the biggest study of its kind called the PREDIMED study based on 7,000 men and women aged 60 at risk of heart disease. They were randomly allocated to one of two diets: a medically approved low-fat diet without dairy or fatty meats or a high-fat Mediterranean diet with lots of cheese, yoghurt, nuts and extra virgin olive oil. The study was stopped early after five years because one diet group was dying more and had a third more diabetes, heart attacks, strokes and breast cancer — you guessed it: the low-fat group.

    This study, published in the New England Journal of Medicine in 2013, has been largely ignored in the UK and in the most recent debate. Despite the adverse health effects of restricting fat at the expense of carbs, it seems there is no stopping the lucrative low-fat food industry. Belief in the benefits of the varied high-fat Mediterranean diet is slowly growing among the informed public, if not yet embraced by the medical profession.

    So why do government and NHS experts persist in repeating false dogma about fat and skipping meals and the power of calorie-controlled diets long after their sell-by date? Well, they probably feel that if they back down and admit their mistakes they lose credibility and won’t be believed again.

    What about the rebel PHC guidelines? There is certainly plenty of sensible advice in the document and good reasons for them to attack the conventional wisdom on saturated fats — which needs re-writing urgently. However, the authors appear to have become entrenched in their own anti-carb views and make the same mistakes, going a step too far and now basing their new guidelines on fragile short-term evidence of the ‘low-carb diet’ and of healthy extra fats as well as putting emphasis on the dodgy glycaemic index of foods which has never (like saturated fat intake) been convincingly linked to poor health long term.

    The battle for the nutritional high ground is too important to be left to evangelical groups defending their positions and measuring how many grams we are allowed. We forget that there are many areas nearly everyone agrees on — avoid processed food, reduced refined carbs, eat more fresh fruit and veg.

    As for me, I don’t think we should try and eliminate any real food items to the detriment of our health. We should now accept that most of the advice and guidelines we get are based on flimsy science that deserves to be constructively challenged. The government should issue its guidelines with a warning that the evidence is shaky until big trials prove their worth. Meanwhile, I will continue to enjoy eating both fat and carbs — as long as they are part of a varied, high-fibre, Mediterranean-style diet — with plenty of high-fat unpasteurised cheese and extra virgin olive oil.

    Tim Spector is professor of genetic epidemiology at King’s College London, honorary consultant physician at Guy’s and St Thomas’s Foundation Hospitals and author of The Diet Myth: The Real Science Behind What We Eat