Over the past decade, nutrition and public health experts have focused on the energy-balance equation - calories-in, calories-out - to explain and address the obesity problem. They have advised the public to reduce their intake and to choose lower calorie foods. They have also called for calorie labelling on the front of food packaging and on restaurant menus, hoping this will change customers’ food choices and encourage the food industry to reduce the number of calories in their products.

However, many food companies no longer fear the calorie-counting message, just as they learned to adapt to the low-fat dietary advice of the 1980s and 1990s. The idea that “a calorie is a calorie” - that all calories are the same - suggests that a calorie of sugar is the same as a calorie of carrots and that the quality of the foods supplying these uniform calories is irrelevant went it comes to weight gain or loss. This plays into the hands of highly processed foods and beverages producers, as it suggests that their products are no different to and no worse than any others, other than the number of calories they contain.

Worldwide, many companies have pledged to reduce the calories in their food products. This can be a positive step, if it means that they will reduce the amount of refined and reconstituted ingredients (such as sugar, refined and modified vegetable oils, modified starches, and extracted and reconstituted meat products) that make up the bulk of many fast and highly-processed foods. Beverage companies, for instance, can now easily manufacture low-calorie and no-calorie sodas using artificial or other highly processed sweeteners to replace sucrose or high fructose corn syrup.

“Big food” corporations have also begun to see the benefits of calorie labelling, rather than feel threatened by it. This may be because many consumers don’t understand calorie counts or find them meaningful, and are unlikely to alter their dietary choices based on them.

This is not to argue against the introduction of labelling. Calorie counts could be used by calorie-conscious consumers to identify the presence of so-called “hidden calories”, in the form of excessive amounts of added vegetable oils, sugar, soy, highly-refined flours, and fatty meat. In this sense, the calorie count may be a crude measure of the quantity of food being consumed.

But here is the kicker: the emphasis on calories allows food companies to take the focus of consumers away from the ingredients, processing methods, and the overall quality of their foods.

Food corporations have also embraced the energy-balance equation. This equation gives equal weight to calories-in (food consumption) and calories-out (physical activity). It, thereby, allows the food industry to attribute half of the blame for weight-gain to individuals’ inactivity, without truly addressing how highly-processed ingredients affect our health or metabolism in other ways.

These ways of understanding food and the body are examples of what I call nutritionism. This ideology of nutritionism is defined by a reductive focus on and interpretation of nutrients within nutrition science, dietary guidelines, and food labelling and marketing. Whether focusing on fats or calories, this approach to food and nutrients has been easily exploited by the food industry, and has made consumers more susceptible to such nutritional marketing strategies.

An alternative to this nutrient-focused approach is to regulate food and beverage products and labelling based on production and processing quality. The composition, proportion, and quality of foods and ingredients should be made more clearly visible on food labels, rather than just drawing attention to the quantity of calories or nutrients.

It is also important for the public to become more food quality literate, rather than just nutritionally literate, if they are to resist the marketing messages of food and drink companies.

The writer is a lecturer in the Melbourne School of Land and Environment at the University of Melbourne, and the author of Nutritionism: The Science and Politics of Dietary Advice. This article has been reprinted from The Guardian.