“Eating fat will make you fat!”, seems obvious doesn’t it? This dietary mantra is deeply and securely enshrined in our 21st century minds, and it seems so self-explanatory that it would be pointless to challenge it. Current dietary guidelines recommend basing each meal around complex carbohydrates such as potatoes, bread and pasta whilst limiting intake of saturated fats where possible. I am sure all will be familiar with the ‘eatwell plate’, endorsed by Public Health UK, which illustrates how our diets should be portioned out by macronutrient content. This approach is common amongst other leading bodies including the World Health Organisation, who recommend that dietary fat should not account for more than 30% of energy intake, with saturated fat comprising less than 10% of total calories consumed. Despite the overwhelming success of this widespread campaign to reduce fat consumption and focus on eating ‘healthy wholegrains’, rates of obesity and metabolic diseases, such as type 2 diabetes mellitus (T2DM), are surging out of control world-wide and cardiovascular disease remains the world’s number one cause of death aside from communicable diseases. Clearly, something has gone very wrong.

The current dogma on macronutrients (fats, proteins and carbohydrates) began in the 1950s, largely through the research of leading nutritional physiologist Ancel Keys. His famous ‘Seven Countries Study’ was the first multinational nutritional epidemiological study to be carried out and remains one of the most cited articles in the field. He demonstrated a positive correlation between dietary fat intake, particularly saturated fat, and heart disease. As one of the most influential nutritional researchers of his time, Keys’ conclusions that saturated fat and serum cholesterol levels were the principal drivers of the Western world’s cardiovascular disease epidemic carried weight and with the support of the American Heart Association they strongly dictated dietary patterns for decades to come.

Recently however, a number of dissenting voices have found an audience. Influential publications like “The Big Fat Surprise” by Nina Teicholz, and “The Case Against Sugar” and “Why We Get Fat” by Gary Taubes have popularised what has become known as the ‘Low Carb High Fat’ diet. Last year, the failed prosecution of eminent South African scientist Professor Tim Noakes for promoting the same message by the Health Professionals Council of South Africa (HPCSA) became another landmark event. Of course, this message is far from novel, and even those who haven’t tried it will be familiar with the now notorious ‘Atkins diet’. Based on similar principles this approach was mainly adopted as a rapid weight loss tool in the 1970s, but was discredited and lost traction in the face of vehement opposition by Dean Ornish and other proponents of plant-based diets. In somewhat of a come-back, there are now dozens of iterations of the ‘low-carb’ (sic) means of eating, and the ‘paleo’ and ‘ketogenic’ diets in particular continue to gain popularity.

How then might one even begin to unpick the plethora of scientific evidence in order to make an informed decision on which camp to join; and trust me there are camps! (Anyone arguing for a “balanced diet” at this stage has totally missed the point). We all must take a point of view here, not least because as individuals we will continue to make dietary choices for ourselves on a daily basis, but as scientists it is our duty to pursue the truth as biology dictates it, and understand what will serve our own health, the health of our families, and the health of our patients best.

This article was written by John Hung and edited by James Hitchen.