When discussing obesity, we often hear that people simply need to exercise more willpower, eat less and make better choices. But this overlooks something rather important: the extraordinary amount of scientific research, behavioural psychology, product engineering and marketing expertise that goes into influencing what we eat, how much we eat and how frequently we want to eat it.
Multinational food corporations such as Nestlé, Kraft Heinz, Coca-Cola, PepsiCo and Mondelez operate in an industry where encouraging repeat purchases and consumption is commercially valuable. These companies have access to sophisticated consumer research, food science, sensory testing and marketing strategies designed to make their products appealing, convenient, recognisable and desirable.
Consider the science behind food formulation. Manufacturers can manipulate combinations of sugar, fat, salt, flavourings, textures and aromas to maximise palatability. Researchers sometimes describe particularly appealing combinations as a food's bliss point. The aim is to create products that consumers enjoy and want to purchase again.
Many ultra-processed foods are also soft, easy to chew, energy-dense and quick to consume. These characteristics can make it easier to eat substantial quantities before the body's fullness signals have had sufficient time to influence eating behaviour.
Then there is the neuroscience. Highly palatable foods can activate brain systems involved in reward, motivation and learning, including dopamine signalling. Dopamine isn't simply a pleasure chemical; it plays an important role in learning which experiences are rewarding and motivating us to repeat them.
Repeated exposure can strengthen associations between particular foods and environmental cues. The sight of a familiar logo, the smell of fast food, an advertisement or even a particular time of day can trigger the desire to eat, sometimes in the absence of physiological hunger.
This is an important distinction: wanting to eat something and needing food for energy are not necessarily the same thing.
The term food addiction remains scientifically debated. Some people experience addiction-like patterns of eating, particularly involving highly palatable foods, but it would be inaccurate to suggest that all ultra-processed foods are inherently addictive in the same way as nicotine or cocaine. Nevertheless, the evidence surrounding reward-driven eating, cravings, conditioned responses and habitual consumption is substantial.
Marketing adds another layer of influence. Food corporations use branding, emotional associations, celebrity endorsements, sponsorships, strategic product placement, promotional pricing, loyalty schemes and increasingly sophisticated digital advertising to shape consumer preferences.
These techniques draw on established principles of behavioural psychology. Familiarity can increase preference. Repeated exposure can influence purchasing decisions. Emotional associations can make products more attractive. Convenience and prominent placement can increase the likelihood that a product is selected.
Importantly, much of this influence operates through automatic cognitive processes rather than deliberate, conscious decision-making.
Intelligence does not make someone immune to psychological influence.
An intelligent, educated person can understand nutrition perfectly well and still experience cravings, respond to advertising, develop habits or find highly palatable foods difficult to moderate. These processes are part of ordinary human cognition and physiology.
Nor is willpower an unlimited resource that operates independently of hunger, stress, fatigue, habits and environmental circumstances. Self-regulation matters, but the conditions in which decisions are made also influence their outcomes.
Now consider the scale of the issue.
According to the Health Survey for England 2024, approximately 66% of adults are overweight or living with obesity, including 30% who are living with obesity. In 1993, the corresponding figures were 53% and 15%.
In other words, the proportion of adults living with obesity has doubled over approximately three decades.
Did the population collectively become less intelligent, less knowledgeable or less capable of exercising self-control? Or should we be examining what has changed in the environment in which people make their decisions?
One major development has been the increasing availability and consumption of ultra-processed foods (UPFs), particularly over the latter half of the twentieth century. Industrial food processing itself is not new, but the variety, accessibility, convenience and marketing of these products have expanded enormously.
The rise in obesity has occurred alongside major changes in our food environment, and numerous observational studies have found associations between higher UPF consumption and obesity. However, correlation alone does not establish that UPFs caused the entire increase in obesity. Changes in physical activity, portion sizes, socioeconomic conditions, sleep and other factors also matter.
What makes the UPF evidence particularly interesting is that we now have experimental research supporting a causal contribution to overeating.
In a controlled study published in Cell Metabolism in 2019, researchers at the US National Institutes of Health compared ultra-processed and minimally processed diets. Participants were allowed to eat as much as they wanted, and the meals offered were matched for several nutritional characteristics.
Remarkably, participants consumed approximately 500 additional calories per day on the ultra-processed diet. They also ate more quickly and gained weight, whereas they lost weight during the minimally processed diet.
This was a small, short-term study, so it cannot tell us that every UPF has the same effect. But it provides compelling experimental evidence that the characteristics of the food environment itself can influence how much people consume.
This brings us back to the argument about personal responsibility.
Of course individuals make decisions about what they eat. Of course energy balance matters. But those decisions are not made in a vacuum. They take place within an environment deliberately structured to attract attention, stimulate desire, encourage purchasing and make consumption exceptionally convenient.
When commercial organisations invest enormous resources into understanding and influencing human behaviour, it seems rather simplistic to dismiss the resulting population-level eating patterns as failures of individual willpower.
If approximately two-thirds of adults are now overweight or living with obesity, perhaps we should be asking fewer questions about what is wrong with individuals and more questions about the environment in which those individuals are expected to exercise self-control.
Understanding how human behaviour is influenced isn't infantilising people. It is recognising that intelligence, knowledge and personal responsibility exist alongside biology, psychology, commercial incentives and environmental pressures.
And if we genuinely want to address obesity at a population level, we need to understand all of them.