The Western diet is characterised by high intakes of refined carbohydrates including sugar, omega 6 fats, saturated fats and processed meats. In addition to this it contains low amounts of micronutrients, fibre and omega 3 oils. Extensive research has invested these components individually to find associations with diseases, and many such associations have been reported in the scientific literature. However, associations between individual food components and a particular condition are problematic because of the risk of confounding variables. For example, in the western diet, foods containing high amounts of sugar also have high amounts of saturated fatty acids. When scientists investigate the associations between saturated fat and disease they immediately come across the problem of not being able to separate the effects of the saturated fat from those of the sugar. Such confounding variables are common in cohort studies and this is why most nutrients in the Western diet can be found to be associated with cancer (here).
This makes an analysis of the Western diet difficult if cohort studies are used to find association with disease at the individual nutrient levels. A way around this is to use whole foods, rather than individuals food components, because this removes some of the risk of confounding variables affecting the association1. For example, cakes often contain high amounts of sugar and saturated fatty acids. Studying the association between intakes of cakes and disease would therefore be potentially less problematic than with the individual ingredients because using whole cakes makes the presence of the saturated fat irrelevant. Now the whole cake, with all its ingredients is the variable of interest, and other ingredients cannot confound the results because they are included in the analysis. However, the problem with this is that cakes might not cause disease, but those who eat cakes might eat another unidentified food that does. Therefore the risk of drawing erroneous conclusions is lessened but is not diminished when assessing whole food components.
The solution to these problems is to analyse the subjects diet as a whole. Analysis of the Western diet as a lifestyle habit removes most of the risk of confounding the results with unknown variables because these are now so few they can be controlled for adequately using statistical tests. Science has been reluctant to investigate whole diets because much of the nutritional literature is infected with methodology from pharmacological research where individuals chemicals are tested in isolation for their specific pharmacological effects. However, more recently the reluctance to investigate lifestyle as a whole or synergistic effects between nutrients and foods has receded as more is understood about the importance of interaction between nutrients. As a result of this shift in paradigm, the Western diet has come under close scrutiny and a number of studies have investigated the association between adherence to the Western diet and disease risk. Such studies have shown that the Western diet is a poor health choice and the likely cause of Western disease.
Comparisons of the Western Diet with more prudent diet comprised of higher intakes of fish, seafood, eggs, vegetables and non-hydrogenated sources of fat have shown that obesity is much more likely in those following the Western diet2. In fact those most closely following the Western diet, consuming high intakes of refined grains, red meat, chips (french fries), processed meats and soft drinks have higher body mass indexes, greater waist girths, higher waist to hip ratios and larger fat masses that those consuming fewer of these foods. This strongly implicates the Western diet in the aetiology of Western diseases because obesity and its associated conditions is a risk factor for diabetes, cardiovascular disease and cancer. The confounding variables are however not completely eliminated because cultural factors can influence diet choice. However, when the Western diet is considered with its associated lifestyle, it becomes more obvious that lifestyle changes and not avoidance of particular foods is the treatment for modern Western disease.
