Why Knowing What Is Healthy Is Not Enough

Most people do not need a psychologist to tell them that exercise is beneficial, that sleep matters or that eating nutritious food is generally preferable to living on takeaways.

Knowing what is healthy and repeatedly doing it are different problems.

This becomes particularly obvious among busy professionals. Someone may successfully manage a demanding job, meet deadlines, look after a family and make complex decisions every day, while repeatedly struggling to exercise consistently or change the way they eat.

That can create a surprisingly painful conclusion:

“I know exactly what I need to do. Why can’t I just do it?”

The answer is usually more complicated than a lack of discipline.

The gap between intention and behaviour

Psychologists sometimes describe this as the intention-behaviour gap.

People can sincerely intend to exercise and still fail to carry out that intention. A systematic review and meta-analysis involving almost 30,000 people found that nearly half of people classified as intending to be physically active did not successfully translate that intention into sufficient activity.

That matters because many attempts at lifestyle change concentrate almost entirely on motivation.

People tell themselves they need to want it more, become more disciplined or find a sufficiently compelling goal.

Motivation matters, but intention is only one part of the process.

The harder question is:

What happens when the moment to act actually arrives?

Imagine somebody intending to exercise after work.

At 8am the plan seems entirely realistic.

By 6pm they have dealt with meetings, travelled home, answered emails and made dozens of decisions. The sofa provides immediate relief. Exercise involves getting changed, leaving the house and tolerating effort before producing any reward.

Skipping exercise makes them feel better immediately.

That immediate relief matters.

Behaviour is partly shaped by its consequences. If avoiding something repeatedly reduces discomfort, avoidance can become increasingly easy to repeat.

Why apparently sensible plans fail

There are many reasons a health plan can break down.

For one person the central difficulty may be exhaustion and excessive workload.

For another it may be perfectionism:

“If I cannot do the full workout there is no point doing anything.”

Someone else may eat differently when stressed because food provides rapid comfort or reward.

Another person may become anxious in a gym because they expect other people to judge their body.

Someone recovering from injury may have been medically cleared to exercise but remain frightened by pain or bodily sensations.

Others repeatedly design programmes that work beautifully during an ideal week but collapse as soon as somebody becomes ill, work gets busy or they go away for a weekend.

The behaviour may look similar from the outside.

The psychological mechanisms can be completely different.

That is why simply telling everybody to “be more disciplined” is rarely an adequate formulation.

Health is also more than body weight

Weight can matter for health, particularly when excess abdominal adiposity contributes to cardiometabolic risk. NICE recommends considering waist-to-height ratio alongside BMI in many adults and advises trying to keep waist circumference below half of height.

But weight is not the only meaningful outcome.

Physical activity has health benefits even in the absence of weight loss, and dietary improvements can improve health without necessarily producing large changes on the scales.

Cardiorespiratory fitness and muscular strength are also strongly associated with health outcomes. Large observational syntheses consistently find lower mortality and morbidity among people with greater fitness and strength, although these associations should not be confused with proof that any single fitness measure determines longevity.

A psychologically sustainable health strategy therefore does not necessarily mean chasing the lowest possible body weight.

The relevant question is broader:

What behaviours would improve this person’s health and quality of life, and what prevents those behaviours from becoming sustainable?

Small change does not mean small ambition

“Start small” is common behaviour-change advice.

It can also be misunderstood.

Someone who is very inactive may ultimately need a substantial increase in physical activity. Someone with significant excess adiposity may eventually need meaningful changes to energy intake. A ten-minute walk is therefore not necessarily the final objective.

But it may be an excellent starting behaviour.

There is an important difference between:

a small first step and a small ultimate goal.

Behaviour-change research supports strategies including graded tasks, goal setting, planning, self-monitoring, behavioural rehearsal and problem solving.

The aim is to establish behaviour that can actually be performed, repeat it, learn from it and progressively develop it.

This is very different from designing the perfect programme and hoping motivation remains high enough to sustain it.

What does psychology contribute?

A psychologist is not there to replace a personal trainer, physiotherapist, dietitian or doctor.

Those professionals answer important questions about what exercise, rehabilitation, nutrition or medical treatment may be appropriate.

Psychology addresses another question:

Why is the person finding it difficult to carry out appropriate health behaviours consistently?

That may involve examining:

• avoidance

• perfectionism

• anxiety

• emotional regulation

• self-efficacy

• rigid rules

• competing rewards

• environmental cues

• habits

• previous experiences of failure

• responses to lapses and setbacks

The aim is not to pathologise ordinary difficulty.

Many people struggling with their health behaviours do not have a psychiatric disorder.

But ordinary behaviour is still governed by psychological processes.

Understanding those processes can help people develop routines that depend less on perfect circumstances or constant motivation.

The real test of a health plan

A useful health plan should not only work on the motivated Monday when everything goes according to plan.

It needs to survive:

a difficult Wednesday,

a stressful Friday,

a holiday,

a poor night’s sleep,

a missed workout,

a restaurant meal,

a deadline,

and the occasional period when motivation simply is not there.

Sustainable change is not the absence of disruption.

It is developing a way of responding to disruption that allows useful behaviour to resume without requiring another complete restart.

That may ultimately be the difference between repeatedly trying to become healthier and gradually building a healthier life.

About the author

Hugo Nel is a Consultant Clinical Psychologist, HCPC Registered Practitioner Psychologist and BPS Chartered Psychologist with over 25 years of clinical experience. He has a BA degree in Sports Science and provides evidence-based online psychological therapy for adults across the UK.