I began my academic career in psychology – a subject I still love. It introduced me to behaviour change models and theories that have proved invaluable. Working in the fitness industry quickly taught me that knowledge and experience only go so far; meaningful progress rarely happens unless people change their lifestyle, habits, and behaviours – and sustain those changes. The countless broken New Year’s resolutions, abandoned diets, and unused gym memberships make that painfully clear.
I was often puzzled by clients who started enthusiastically but struggled to get going, or quickly fell off track and slipped back into old patterns. In my younger years, I remember thinking – naively and with some frustration – that those wanting to lose weight simply needed to “eat less and exercise more.” If only it were that simple. I was equally baffled by how many people continued behaviours they knew were harmful, even while fully aware of the risks.
Over the next few newsletters, I’ll explore key models and theories of health behaviour change – alongside a few lesser known ones. In this article, I’ll begin with perhaps the most widely recognised framework: the Health Belief Model.
Social cognition models
Many foundational theories of health behaviour are rooted in value-expectancy principles. At their core is a simple idea: behaviour is shaped by the subjective value a person places on an outcome and their expectation that a specific action will achieve it. In other words, these models treat the mind as an information processing system – one that evaluates inputs such as perceived threats, anticipated benefits, and personal beliefs, weighs them up, and then produces outputs such as intentions or concrete actions.
The Health Belief Model
The Health Belief Model is arguably the most influential framework in health behaviour research. Developed in the 1950s by social psychologists Hochbaum, Rosenstock, and Kegels at the U.S. Public Health Service, it began as a practical attempt to understand why people were not taking up free tuberculosis screening despite its availability and clear benefits.
The Health Belief Model explains the factors that influence whether individuals adopt – or avoid – health promoting behaviours. According to the model, the likelihood that someone will engage in a healthy action (e.g., becoming more physically active) is driven by two key appraisals:
1. Perceived threat of a health problem.
2. Outcome expectations – the perceived pros and cons of taking action.
Key components
Demographics and background factors: Characteristics such as age, gender, ethnicity, and socioeconomic status shape how people interpret health information and perceive risk. These factors influence the beliefs individuals form about illness and preventive behaviours.
Perceived threat: Two elements contribute to perceived threat:
1. Perceived susceptibility: How likely someone believes they are to develop a particular problem. For example, a person who understands that a sedentary lifestyle raises their risk of type 2 diabetes may feel more vulnerable – and more motivated to change.
2. Perceived severity: How serious they believe the consequences would be. For example, an older adult whose spouse and close friend have developed coronary heart disease due to inactivity is likely to feel a greater personal threat than a teenager surrounded by healthy peers.
Outcome expectations: These include:
1. Perceived benefits: Belief in the efficacy of the recommended action.
Example: “If I stop smoking, I’ll save money, improve my skin and hair, and protect my lungs.”
2. Perceived barriers (or costs): Obstacles – financial, practical, social, or psychological.
Example: “Joining a gym will cost £30 a month and mean giving up a few nights out with friends.”
People weigh benefits against barriers to decide whether action feels worthwhile. If the perceived benefits (better health, more energy, reduced risk) outweigh the barriers, action is more likely.
Combining threat and expectations: Perceived threat – combined with the balance of benefits versus barriers – shapes the overall likelihood of adopting preventive behaviours. For example, if someone feels at risk due to inactivity and believes the benefits of exercise outweigh the challenges, they are more likely to start. If they feel little risk or see the barriers as too high, change is unlikely.
Cues to action: Even when perceived threat and outcome expectations favour change, people often need a cue to action – a prompt that triggers behaviour. Cues can be:
• Life events (e.g., a friend’s illness).
• Environmental cues (e.g., public health campaigns).
• Behavioural prompts (e.g., a message from a gym after missed sessions)
Such prompts increase the likelihood of taking preventive action.
Strengths, limitations, and critique
Strengths: The Health Belief Model has strong intuitive appeal. Raising risk awareness and highlighting benefits can increase uptake of healthy behaviours. It offers a useful foundation for understanding the cognitive factors people consider when deciding whether to change.
Limitations:
• Rationality and habit: The Health Belief Model assumes people act as rational decision makers who weigh pros and cons. In reality, many health behaviours (smoking, overeating, tooth brushing) are habitual or emotionally driven, not re evaluated each time.
• Limited predictive power: The Health Belief Model often explains only a modest portion of variance in behaviour. It’s not always clear how its components interact, or which matter most in real world decisions. While demographics are acknowledged, the model offers little guidance on how they translate into perceptions and actions.
• Emotional, social, and cultural influences: Decisions are shaped by fear, denial, social norms, peer influence, and culture – factors the Health Belief Model addresses only partially. Even people with severe symptoms (e.g., experiencing a heart attack) may delay seeking treatment – not through lack of information, but because they can’t imagine it’s happening to them.
• Self efficacy (later addition): The original model omitted self efficacy – confidence in one’s ability to act – a key predictor of behaviour. Its later inclusion aligned the Health Belief Model more closely with Social Cognitive Theory, which recognises personal agency and social context.
• Designing interventions: While the Health Belief Model helps explain how people think about health threats, evidence that it’s effective as a standalone framework for designing or evaluating interventions is limited. Its cognitive focus can oversimplify the real world mix of emotion, habit, social context, and structural constraints.
In summary, real change comes from sustained habits, not just knowledge. The Health Belief Model suggests we take action when we feel at risk (through perceived susceptibility and severity) and believe the benefits outweigh the barriers – shaped by our background and nudged by cues like reminders or life events. It is a useful lens for understanding why people might change, but it has limits: it assumes rational decision making, has modest predictive power, and originally overlooked self efficacy and the influence of emotions, habits, and social context. The upshot: use the model to clarify motivations, then pair it with habit design, environmental tweaks, social support, and confidence building to help people actually follow through.
