Obesity: How high is my risk and how is it diagnosed?

1. What increases the risk of obesity?
2. What is the role of genetics?
3. What is the significance of one’s own lifestyle?
4. What is the influence of external living conditions?
5. How do stress and depression affect body weight?
6. How is obesity diagnosed?
7. When are children and adolescents considered obese?

Genetic predisposition has a major influence on a person’s individual risk of developing obesity in the course of his or her life. Various studies suggest that genes contribute to the development of obesity by 30 to 70 percent. For example, genes influence how much food a person eats and how it is metabolized. Observational studies of twins growing up separately or adopted children show that the body weight of children is more likely to be determined by their genetic predisposition than by the environment in which they grow up.

Obesity results from a complex interplay of genetic predisposition and environmental factors. However, a genetic predisposition does not necessarily lead to obesity. Body weight can be significantly influenced by the lifestyle that a person chooses.

In recent decades, the number of people with obesity has risen sharply in industrialized nations. Researchers think this can mainly be attributed to modern lifestyle habits. In a changing world of work, sedentary and less physically strenuous activities are increasingly being performed. Digitalization and the use of smartphones and streaming services also encourage sedentary behavior in leisure time – both among adults and children.

At the same time, the supply of industrially produced, highly processed foods has multiplied over the last 50 years. These products are often low in fiber but high in sugar and fat. Soft drinks with a high sugar content, fast food and snacks are available everywhere and can be consumed quickly.

Studies show that obesity is more widespread in population groups with a low level of education and low social status. On the one hand, this is due to economic factors: Foods such as fruit, vegetables and wholegrain products, which contribute to a healthy diet, are often more expensive and more difficult to access for people on a low income. Highly processed, energy-dense products such as snacks and fast food, in contrast, are often inexpensive and available everywhere. In addition, health literacy and therefore knowledge about a healthy lifestyle is lower in social classes with a lower level of education. As a result, less attention is usually paid to healthy eating.

The living environment also influences people’s motional behavior. Especially in cities, socially disadvantaged areas often have fewer green spaces, bikeways, playgrounds or sports clubs. In addition, there may be factors such as increased stress due to noise load, air pollution or social isolation.

Measurement of body composition

Various methods are available for determining body composition. In bioelectrical impedance analysis (BIA), a weak electric current is passed through the body using electrodes. Based on the electrical resistance that can be measured, conclusions can be drawn about the water or fat content of the body. Muscles contain more water than body fat and thus increase electrical conductivity.

Body composition tests should be used if muscle wasting, which may be associated with obesity, is suspected. If muscle mass is reduced, experts speak of sarcopenic obesity.

During weight loss, bone density may decrease – especially in older people. If this is suspected, a bone density measurement is therefore recommended to accompany treatment. As a standard, this measurement is carried out using dual energy x-rayabsorptiometry (DXA).

Determining the state of health

In addition to determining the body weight, the BMI and the waist circumference, the attending physician should also carefully examine the patient’s general state of health before starting obesity treatment. The following aspects should be determined and taken into account in the subsequent treatment plan:

• Existing concomitant and secondary diseases:
  Does the patient already have concomitant and secondary illnesses such as cardiovascular disease, diabetes, joint problems, cognitive impairments (e.g., dementia) or psychological stress?
• Existing risk factors for cardiovascular and metabolic diseases:
  Determination of blood pressure, blood sugar and blood lipid levels.
• Previous nutrition and exercise behavior:
  When, how often, how much and for what reason does the patient eat? How is the patient’s physical activity and physical fitness?
• Presence of an eating disorder:
  Does the patient have a binge eating disorder (BES) or night eating syndrome?
• Clarification of medical causes:
  Medical clarification when hormone-related metabolic disorders are suspected, for example hypothyroidism or Cushing’s syndrome, which may be the cause of obesity.

During obesity treatment, the relative weight loss (RWL) should be determined regularly in addition to body weight and BMI. A weight reduction of at least 5 percent of the initial weight should be aimed at because it may already have a positive effect on health, for example on blood lipid levels and existing diabetes.

An unhealthy lifestyle – a high-calorie diet and too little exercise – can lead to overweight and obesity even in children and adolescents. If obesity is already present in childhood, the risk of other diseases also increases. In addition, overweight and obese children are more at risk of being bullied at school and suffering from depression.

As with adults, the body mass index (BMI) is also used as a unit of measurement to define overweight and obesity in children and adolescents. However, due to growth, age and gender play a decisive role in the assessment of the BMI. Against this background, age- and gender-specific reference values, known as BMI percentiles, are used to estimate body weight in relation to height for children and adolescents. The calculation of these percentiles for the BMI was based on the height and body weight data of more than 34,000 girls and boys aged 0 to 18 from different regions of Germany.

Taking age and gender into account, overweight in children and adolescents is defined as a BMI that exceeds the 90th percentile. This means that 90 in 100 children of the same sex and age have a lower BMI. If the BMI exceeds the 97th percentile, children and adolescents are considered obese.

Find more information on obesity in children and adolescents on the “Preventing Obesity” information portal of the Federal Institute of Public Health (Link in German).

The clever.gesund portal from Helmholtz Munich, which is sponsored by the AOK Bayern health insurance fund, is aimed directly at young people and provides information about a healthy lifestyle (Link in German).