Much of the rise of obesity is precisely a consequence of free-market economics. For example, fast food has become cheaper, in part because of mechanisation and in part because the workers producing it are paid less and less.

At the same time, the economic forces that propelled 1960s women away from the kitchen and into jobs also propelled families towards processed foodstuffs, eating out, and snacking.

Epigenetics is the study of heritable changes in gene expression that occur without a change in the DNA sequence. Research suggests that epigenetics play a major role in determining a person’s predisposition to obesity.

However, epigenetics is a relatively new field. More research is needed to better understand the underlying mechanisms through which genetic and epigenetic factors interact to determine metabolic characteristics.

Epidemiology is the study of how often diseases occur in different groups of people and why. Since body fat can be measured in several different ways, statistics around the epidemiology of obesity vary between sources.

BMI is the most useful population-level measurement of obesity as it is the same for both sexes and for all ages of adults. However, it should be considered a rough guide because it may not correspond to the same degree of fatness in different individuals.

Media in the 21st century is highly interactive. Users of new media are active producers of content and information, whether sending an email or using internet collaboration tools.

How people interact with media is changing – changing fastest within the younger generation who adopt new technologies and practices quicker. New media will play a huge role to tackle childhood obesity, along with more traditional media to influence their parents.

There are pronounced socioeconomic inequalities in the prevalence of obesity. There is an urgent need to address the factors that contribute to the emergence of these inequalities in early life, as recent research suggests that obesity may represent a major pathway through which social inequality becomes biologically embedded.

There is also a concomitant need to identify evidence-based initiatives that can be used to reduce socioeconomic inequalities in obesity.

Correlation between two events or variables simply indicates that a relationship exists, whereas causation is more specific and says that one event actually causes the other. For example, a lack of exercise is often associated with being overweight, but it is very difficult to prove that a lack of exercise actually causes someone to be overweight.

The causes and consequences of obesity are often difficult to determine. Addressing this is important, as the prevention and treatment of any disease requires that interventions focus on causal risk factors.

Everywhere you go, humans are engaged in conversation. Our minds are built for narratives – especially narratives about other humans. Narratives are contagious: they spread from one person to another. Some narratives disappear quickly, some last a long time.

So far, the prevailing obesity narrative is that this is a condition largely caused by people’s lifestyle choices (primarily pertaining to eating too much and not moving enough), and that obesity can be prevented and reversed by getting people to make better choices. However, emerging evidence suggests that obesity is instead a complex, multifaceted heterogeneous disorder.

People have a cognitive bias to assume that an individual’s actions depend on what ‘kind’ of person that individual is, rather than on the social and environmental forces that influence them. Obesity is a salient appearance characteristic, which can easily trigger attribution bias.

For example, obesity is often characterised as nothing more than greed and a lack of willpower. The truth is far more complex, and the role of genetics is the subject of a great deal of contemporary research into the problem.

Humans like to be (and appear) consistent with what we have already done. Once we have made a choice or taken a stand, we will encounter personal and interpersonal pressures to behave consistently with that commitment. Those pressures will cause us to respond in ways that justify our earlier decision.

Brands can do a lot to help tackle obesity. For example, colour-coded nutritional information on packaging makes it easier for consumers to tell how a particular foodstuff contributes to their overall nutritional intake.

Point of purchase strategies, when people make poor and impulsive decisions about what and how much to buy and consume, are difficult to recognise and resist. People lack insight into how marketing practices interfere with their ability to routinely eat a healthy, balanced diet and it is difficult for public health entities to protect consumers.

Distribution channels refer to the networks used to get a product from the manufacturer or creator to the end user. Knowledge of supply chain dynamics helps us recognise what opportunities children have to purchase healthy and unhealthy snacks.

This knowledge is important so we know where content might be displayed and how we can craft messages which trigger the right behaviour at the right time.