Monday May 23 2016
Can you stop worrying about counting calories?
"Low-fat diet bad for your health and cutting back on meat, dairy and eggs a disastrous mistake," the Daily Mirror reports.
That is the main message of a controversial report attacking official UK guidelines on diet and weight loss.
The report suggests it doesn't matter how much saturated fat we eat, and doesn't recommend counting calories.
Critics have pointed out there were no agreed criteria about what evidence would be considered in the report, leaving it open to accusations of cherry-picking.
This means the report's authors may have promoted evidence supporting their argument while ignoring evidence they saw as unhelpful.
Dr Mike Knapton, associate medical director at the British Heart Foundation (BHF), said: "This report is full of ideas and opinion.
"However, it does not offer the robust and comprehensive review of evidence that would be required for the BHF, as the UK's largest heart research charity, to take it seriously."
Who produced the report?
The report was published by the Public Health Collaboration, a not-for-profit organisation described as being dedicated to informing the public and implementing healthy decisions.
The report is said to follow decades of work and experience that founding and advisory board members have gathered through working with thousands of patients to improve their health.
The listed advisory board members are named health professionals, including dietitians, GPs, a cardiologist, a diabetes specialist and a psychiatrist. They also list a number of patrons.
It is unclear where Public Health Collaboration's funding comes from. Nor is it clear who wrote the report.
No author or authors are named, and it does not appear to have been peer-reviewed by independent experts.
The aim of the report is said to be to raise concerns about the government's current recommendations about healthy eating and weight loss, and also provide new evidence-based solutions to help people obtain healthy lifestyles and improve public health.
What does the report say?
The report states the current prevalence of obesity in the UK is 25%, costing the economy £47 billion a year.
It summarises the recommendations of the current Eatwell Guide for healthy eating, saying it has three main concerns with this guidance:
- the avoidance of foods because of their saturated fat content
- the dietary reference value of no more than 35% total fat
- the quality and quantity of carbohydrates
The researchers say current recommendations given on NHS Choices are to opt for low-fat dairy options, as high saturated fat can increase the risk of heart disease.
They highlight a large US cohort study from 2010 that concluded saturated fat intake was not associated with risk of cardiovascular disease.
They quote several other observational studies that supported the notion that high-fat dairy was not linked to obesity or cardiovascular and diabetes risk.
The researchers say: "In retrospect, there was never any strong evidence to recommend reducing total and saturated fat consumption, and in the 30 years since, the deteriorating health of the UK population suggests such advice may have been a dire mistake, however well intentioned."
They consider that if people had been opting for foods in the natural form, rather than manufactured low-fat foods, we wouldn't have the obesity problem we do today.
The Public Health Collaboration concludes the UK should stop recommending the avoidance of high saturated fat foods and focus on consuming food in its natural form – however much saturated fat it contains.
No more than 35% total fat
The authors question recommendations that too much fat in your diet raises the risk of heart disease and makes you overweight, saying this is not backed by scientific evidence.
They reference a trial published this year, which found people on low-carb diets experienced more weight loss than people on low-fat diets, and say how recent US dietary guidelines have removed their previous 30% total fat limit and no longer place any restriction on fat.
They conclude the UK should remove the recommendation to eat no more than 35% total calorie intake from fat and instead focus on the health benefits of eating food in its natural form – regardless of fat content.
Quality and quantity of carbohydrates
As the authors say, good blood glucose control is important to maintain health and reduce the risk of developing diabetes or pre-diabetes conditions.
However, they say eating lots of foods that raise blood glucose and promote the release of insulin are factors likely to increase this risk – and high carbohydrates do just that.
They discuss the glycaemic index (GI) of different foods, and say the UK's Eatwell Guide "illogically" recommends high-GI foods, advising people to "base meals on potatoes, bread, rice, pasta or other starchy carbohydrates".
They suggest that such recommendations are behind the increase in rates of type 2 diabetes and obesity.
The Public Health Collaboration concludes people should avoid foods that have a high carbohydrate density, and instead focus on food and drink that has a carb density of less than 25%. Such foods are usually in their natural form.
"Real food" lifestyle
The Collaboration sets out a new form of the Eatwell Guide called "The Real Food Lifestyle", which has a 50:50 split of fats and proteins against carbohydrates, but all food and drinks on the wheel are in their natural form.
They emphasise carbs with a density less than 25% and a minimum of 1g protein per 1kg bodyweight per day.
They also emphasise eating "real" foods that will fill you and avoiding processed "fake foods", which won't.
For example, they recommend natural oils and butter, including coconut oil, ghee, lard and cold-pressed olive oil – the "fake" ones are rapeseed, sunflower and corn oil – and no juices or processed sugar products.
If you were being critical you could argue that the division between “real food” and “fake food” is scientifically meaningless.
What evidence is this based on?
The report is presented in the form of a narrative, where individual pieces of evidence are cited as coming from particular studies. A list of references is then provided at the end.
However, the report does not provide any information about how the authors identified and selected the research reviewed.
As such, it is not possible to say this was a systematic review, and we cannot know for sure this is a balanced report that has reviewed all evidence relevant to diet and nutrition.
The standard warnings about cherry-picking – evidence that is inconvenient may be ignored – apply.
Also, without reviewing the individual studies referenced, it is not possible to appraise the quality and strength of this evidence. However, many are observational.
There is potential for various sources of confounding and bias to influence associations between self-reported diet and health outcomes, such as inaccurate recall on food questionnaires or the potential influence of other unmeasured health and lifestyle factors.
It can be difficult to know to what extent a particular outcome can be directly attributed to a particular food – or the absence of it.
The report further says it "clearly and concisely provides an insight into the decades of work and experience that our founding members and advisory board have accumulated from working with thousands of patients".
But it's not known what sort of experience or data from patients has contributed to informing this.
We also don't know, for example, whether the recommendations on fat and carbohydrate intake would be applicable to all stages in life, or whether there might be different advice for children.
The report makes much of the fact that in spite of UK dietary guidelines, the number of people with obesity and type 2 diabetes has grown in recent decades. However, this does not prove that the guidelines are to blame.
What response has there been to the report?
The report has attracted quite considerable criticism.
Some professionals, such as the professor of diet and population health at the University of Oxford, note the lack of systematic review methods and accuse the report of potentially cherry-picking studies to support its viewpoint.
Other studies presenting contradictory findings do not seem to have been included, they say.
As a scientist from the University of Reading says: "As with any public health measure, it is important that any recommendations are based on solid evidence and take the wider implications of implementation into account. That doesn't seem to be the case in this instance."
Professor Tom Sanders, emeritus professor of nutrition and dietetics at King's College London, says statements such as "fat doesn't make you fat", "saturated fat doesn't cause heart disease", and "avoid 'low fat' " are potentially harmful and could mislead the public.
Other opinion is more mixed, with one professor saying the report has "good, bad and ugly elements in it". There are views that snacking and added sugar are to be avoided, but ideas that we should eat limitless fat and cut out sugar altogether are criticised.
BBC news quotes Dr Alison Tedstone, Public Health England's chief nutritionist, who says: "In the face of all the evidence, calling for people to eat more fat, cut out carbs and ignore calories is irresponsible."
She says thousands of scientific studies have been considered when making current UK health and nutrition recommendations.
"It's a risk to the nation's health when potentially influential voices suggest people should eat a high-fat diet, especially saturated fat," she says.
"Too much saturated fat in the diet increases the risk of raised cholesterol, a route to heart disease and possible death."