Being overweight changes how we perceive our health in middle age

Hanne is 58 years old and still goes to work every day, but her body no longer cooperates as it once did. She quickly becomes short of breath on the stairs, her knees hurt and she increasingly turns down invitations after work. She knows that her weight has crossed the threshold into obesity, but what troubles her most is the feeling that her health has slipped from “good” to “less good”. She does not feel seriously ill – but she does not feel well either.

These kinds of self-rating are central to a new study in Denmark that examines the relationship between weight, waist circumference and self-rated health among people aged 50–65 years. The study was conducted within the Better Health in Late Life cohort at the Department of Clinical Epidemiology and the Centre for Population Medicine at Aarhus University Hospital and Aarhus University, with Henrik Toft Sørensen as senior author. He is a clinical professor and head of the Department of Clinical Epidemiology, and the results have been published in the International Journal of Obesity.

The main finding is that the proportion of people who described their health as “less good” or “poor” increased with weight. A smaller share of normal-weight people reported poor health.

Among people who were overweight, the proportion was higher; among those with obesity, higher still. And among those with severe (class II) obesity, around four in ten rated their health at the poor end of the scale – even though the cohort as a whole belongs to a relatively resourceful segment of the population. In other words, the correlation also applied among people who generally do well socially and health-wise, and not only among people already severely disadvantaged.

This means that many middle-aged people are already experiencing a loss of health that has not yet necessarily been registered as illness.

Henrik Toft Sørensen explains that self-rated health is often debated because measuring it objectively can be difficult. But that is precisely why researchers frequently use it: a single question can capture many dimensions of health at once – from pain and fatigue to mental well-being and physical functioning. For the individual, it very concretely assesses how everyday life actually works.

“When so many people with severe obesity rate their health lower, it suggests that weight is rarely a stand-alone issue but is often accompanied by other burdens such as cardiovascular disease, type 2 diabetes and depression,” says Henrik Toft Sørensen.

He stresses that the findings cannot be reduced to a single factor but instead reflect a more complex health situation among the heaviest participants.

Severe obesity is widespread in middle age

The road to the new study began several years before the first analyses. The research group in Aarhus wanted to build a large cohort of people in the later stages of working life in order to shed light on factors that cannot be seen in registers alone – including lifestyle, physical activity, smoking, mental well-being and social and economic conditions. There was already interest in diabetes and obesity, but the researchers lacked people’s own voices.

In this context, they chose self-rated health as one of the first focus areas, because a single question can reveal a great deal. Experience from other countries has shown that responses to the question “How would you rate your overall health?” reflect both known diagnoses and less visible problems such as pain, fatigue, reduced function and mental strain – factors that do not always end up as a clear code in a register.

Together with Statistics Denmark, the researchers drew a sample of people aged 50–65 years, who were invited via e-Boks, a digital postbox, to take part in a comprehensive questionnaire. About one third agreed, corresponding to just under 88,000 people.

When the researchers began to examine the weight distribution in the material, they were surprised. Of the participants, 5,407 had a body-mass index (BMI) above 35 – that is, severe obesity. This proportion is probably a conservative minimum estimate, since the participants were generally healthier and better educated than the population as a whole. In the general population, in which more people are disadvantaged socially and health-wise, the share with severe obesity is likely to be even higher.

“We did not expect so many to be in the heaviest category, since we already found lower mortality and higher levels of education in the group. This suggests that severe obesity is very widespread – and probably even more widespread than we found here,” says Henrik Toft Sørensen.

The data are held by Statistics Denmark and can be linked to health registers under strict data-security rules. This enables researchers to follow which diseases participants develop and which contacts they have with the health services over time without requiring them to complete new questionnaires.

A clear pattern across weight classes

The researchers used participants’ self-reported height and weight to calculate BMI and divided them into normal weight, overweight and two obesity classes. Responses to the question “How would you rate your general health?” were grouped into two categories: good versus less good or poor health. On this basis, the researchers calculated the proportion with poor self-rated health in each BMI class and the ratios between the groups.

After adjustment for age, sex and education, the prevalence of poor self-rated health among the individuals with severe obesity was several times higher than among those of normal weight.

“We are essentially seeing a staircase, in which each step up the BMI classes is followed by poorer self-rated health. This underlines that not only the very heaviest people experience their health as impaired. The curve starts to bend much earlier,” says Henrik Toft Sørensen.

The researchers also found a clear pattern in which both higher BMI and larger waist circumference are associated with poorer self-rated health. The correlation already begins at BMI levels that have traditionally been regarded as unproblematic, suggesting that people’s self-rated health is affected earlier in the weight trajectory than is often assumed.

When one question brings together many aspects of health

This overall pattern raises the question of what actually lies behind the lower self-rated health: whether it is weight itself or whether BMI and waist circumference instead reflect a broader strain on the body.

However, the figures alone cannot determine what drives what. Weight, waist circumference and self-rated health were measured at the same time, meaning that the study cannot show whether weight leads to poorer self-rated health or whether poorer self-rated health can also contribute to weight gain.

It therefore remains unclear whether high body weight in itself impairs health or whether pre-existing health problems affect both the body and how people rate their health.

As Henrik Toft Sørensen sees it, severe obesity often occurs alongside other diseases. Many people in the highest BMI group have cardiovascular disease, type 2 diabetes or osteoarthritis. In addition, the researchers found higher rates of depression and other mental disorders, and many participants report pain, sleep problems or shortness of breath – problems that do not always result in a single, clear diagnosis but are very noticeable in everyday life.

“If you are in pain, become short of breath easily and also struggle with mental health problems, you are less likely to say that your health is really good, regardless of whether you have one specific diagnosis or several. It is precisely this overall burden that we believe self-rated health captures better than any single measurement,” he says.

When weight becomes one burden among many

The analyses also show that BMI does not carry the same significance in all groups. Among people whose health is already strongly affected by depression, high stress levels or serious somatic illness, the difference in self-rated health between those with normal weight and those with obesity is smaller than in the overall data. When illness becomes a dominant factor, weight becomes one burden among many – and not necessarily the most important one.

Beyond health conditions, Henrik Toft Sørensen also points to social and mental mechanisms. Overweight and obesity are often associated with stigma and with the experience of falling short of the ideal, both in private life and at work.

“We cannot see bullying, hostile looks or social isolation in the registers, but we know that many people with overweight experience this in their everyday lives. It is reasonable to assume that such experiences influence both how people rate their own health and how easy or difficult it is to change the circumstances that place them under strain,” he says.

He stresses that the figures should not be read as a judgement of the individual. They describe patterns at the population level. Even among those with severe obesity, many rate their health as good or very good but only a few say that their health is “excellent”.

“Some people with overweight are doing really well, and remembering that is important. But when we look at the group as a whole, the risk of experiencing poor health is clearly elevated, and we should take that seriously in both prevention and treatment,” says Henrik Toft Sørensen.

From snapshot to early warning signal

The current study provides a sharp snapshot of how weight and self-rated health are linked among Danes aged 50–65 years. It shows that high body weight and large waist circumference in this age group are often accompanied by a perception of poorer health – even within a relatively affluent segment of the population. In addition, the findings suggest that this perception may contain information that is not yet visible in diagnoses or registers.

The research group is therefore continuing to investigate whether people who describe their health as “less good” at that age actually face a higher risk of later illness, hospitalisation and premature death – even when their other risk profiles are taken into account.

A central hypothesis is that self-rated health can function as an overall marker of health deficits that have not yet been fully captured by diagnoses. In other words, it may act as an early summary of problems that have not yet been named in medical records.

“Our hope is that self-rated health can be used as an early warning signal. If it turns out that a single question predicts later illness better than we thought, we will have a very simple tool for identifying the groups to which we need to pay particular attention,” says Henrik Toft Sørensen.

For Henrik Toft Sørensen, the results point to one overarching message:

“Preventing severe obesity needs to happen much earlier than the fifties and sixties. At the age we are looking at here, it is probably too late for many people to fully reverse the trend. But we can learn something about the patterns that lead to a life in which people experience their health as less good – and use that knowledge much earlier in life,” he says.