Obesity is genes, bad habits or predispositions?

When is obesity diagnosed: is BMI or body composition analysis more important?

The most popular and simplest tool for diagnosing obesity is the Body Mass Index (BMI) . This formula divides body weight (in kg) by height (in meters) squared. A healthy weight range is between 18.5 and 24.9 kg/m²; overweight is 25-29.9 kg/m², and obesity is diagnosed at a score of 30 kg/m². Because the BMI formula does not distinguish body composition, it is generally used primarily for screening purposes.

People who do strength training and have significant muscle mass may get a result indicating they are overweight or obese, which does not actually reflect reality. Therefore, another tool for assessing obesity is waist circumference measurement. This area was chosen for measurement due to the observed correlation between waist circumference and an increased risk of heart disease, metabolic disorders, cancer, and premature death. A healthy result for women should be below 80 cm, and for men below 94 cm.

Meanwhile, as research has progressed, it has turned out that both BMI and waist circumference are still not always fully reliable indicators. There are people with the TOFI phenotype (thin outside, fat inside), who have a normal BMI but possess excessive body fat and too little muscle mass.

To measure body fat content, it is necessary to perform a body composition analysis, i.e., bioelectrical impedance. Such a measurement can be performed in a dietitian's office and increasingly often at the gym. To ensure that the body composition analysis result is reliable, it is best to perform it in the morning after using the restroom and to avoid alcohol, exercise, and smoking on the day before the test.

Why is obesity a disease?

For years, adipose tissue was considered merely an energy storage site for the body. However, numerous studies have proven that it secretes a range of substances that influence the functioning of organs and tissues. It is now recognized as an endocrine organ because it releases many proteins that exhibit effects typically attributed to hormones. A certain amount of body fat is essential for processes such as puberty and maintaining fertility, but an excess leads to pathological states. Fat cells located in the abdominal area—specifically visceral fat surrounding the organs—are particularly dangerous.

Adipose tissue plays a significant role in metabolic processes:

• It secretes many substances that not only influence the regulation of hunger and satiety (leptin, visfatin, resistin) but also exacerbate inflammation (interleukin-6).
• it affects the metabolism of steroid hormones (aromatase, dehydrogenase).
• Fat cells possess numerous receptors for substances such as insulin, glucagon, TSH, and angiotensin, which can hinder their proper functioning in the desired areas of the body.

Although these names sound complicated, they illustrate what a complex, multi-functional "organ" adipose tissue truly is. Its excess leads to insulin resistance, impaired glucose tolerance, and ultimately, type 2 diabetes.

Furthermore, it influences the development of hypertension, cholesterol disorders, chronic systemic inflammation, and an increased risk of blood clots. Unfortunately, each of these disorders triggers further complications and contributes to the development of metabolic syndrome. Advanced obesity usually requires pharmacotherapy to break the cycle of self-reinforcing disorders.

Genetic factors of obesity

To date, no single gene directly responsible for obesity has been identified. Mutations in individual genes or entire gene clusters can have an impact, potentially leading to metabolic, absorption, or appetite disorders.

Obesity can also be a component of rare, genetically determined syndromes. Their pathogenesis is not fully understood, but it often results from damage to more than one gene. In addition to pathological obesity caused by factors such as hyperphagia and a basal metabolic rate reduced by nearly 15%, these syndromes are also accompanied by other developmental defects (intellectual disabilities, organ disorders).

• Polygenic obesity

The most common form of obesity is polygenic. This type of obesity is the result of gene-environment interactions. Susceptibility to obesity is determined by genes, but the quantity and quality of one's diet and physical activity determine whether excess body weight will occur. Depending on the genotype, the tendency toward obesity increases to varying degrees. However, a strong correlation between obesity and a lack of physical activity is evident. Introducing regular exercise and controlling dietary fat intake is the best way to fight excess weight and protect against the risk of obesity.

• Genetic testing

An increasing number of nutrition clinics are offering genetic testing to personalize dietary recommendations. Awareness of carrying specific gene polymorphisms that increase the risk of metabolic disorders can be utilized when implementing interventions. It should be remembered that such tests do not account for all genes, and focusing on a selective group may carry certain risks.

The influence of gut microbiota on obesity

The human microbiota is incredibly diverse. Different species of microflora, characteristic of specific areas, inhabit different parts of the digestive tract. This diversity is essential because these bacteria have varying metabolic activities that influence human physiology. They facilitate the breakdown of undigested fiber, can produce essential vitamins, and regulate host immunity. When imbalanced, certain bacteria increase calorie absorption, promote fat storage, and affect appetite. Conversely, a healthy microbiome supports proper metabolic processes and regulates appropriate calorie intake during meals.

So, how can you take care of a healthy gut microbiome? You need to nourish it properly with fiber-rich products. It is worth enriching your daily diet with oats, barley, peas, beans, apples, citrus fruits, psyllium husk, and inulin. Scientific studies show that including 10 g of inulin in your daily diet contributes to weight loss and a reduction in body fat compared to a placebo group.

Another group of substances that influence the proper composition of the gut microbiome is polyphenols. These are found in plant-based products and are primarily known for their antioxidant and anti-inflammatory properties. Together with the gut microbiota, they form an interdependent duo. The richest sources of these ingredients are: berries, cocoa, green and black tea, legumes, pomegranate, flaxseed, and cereal products.

The mechanisms and relationships described show how complex the human body is and what an impact a balanced diet has on every aspect of it. When we eat a healthy and varied diet, we simultaneously support our gut microbiome, which in turn influences satiety, regulates glucose, and reduces the urge to snack, making it easier for us to make health-conscious food choices.

Diseases that contribute to obesity

In addition to genetic predispositions to obesity, there are medical conditions that can directly or indirectly make it difficult to maintain a healthy body weight. Secondary obesity occurs in certain endocrine and genetic disorders, as well as in diseases of the hypothalamus and pituitary gland. Weight issues are observed in people struggling with hypothyroidism, which can result from pituitary damage, Hashimoto's disease, or thyroid removal.

Another group of diseases involves the hypothalamus (an area in the brain), which is responsible for hormone secretion, circadian rhythms, and feelings of hunger and satiety. Disorders in this area can be associated with excessive appetite and a lack of satiety. Examples of such diseases include Prader-Willi syndrome and Bardet-Biedl syndrome. Problems with hyperphagia can also occur following damage to the hypothalamus caused by radiotherapy or surgical intervention.

It is not only medical conditions but also pharmacological treatments that can affect satiety or increase appetite. Among the medications that increase the risk of excessive fat accumulation are: neuroleptics, antidepressants, and antiepileptic drugs, sedatives, steroid hormones, beta-blockers, as well as antidiabetic drugs—insulin and certain sulfonylurea derivatives. This does not mean that you should stop taking these medications, as they are prescribed as primary treatments for certain diseases. When using the aforementioned pharmacotherapy, you should pay closer attention to physical activity and your food choices.

Environment and obesity

The most common form of obesity among children, adolescents, and adults is simple obesity, which results from a positive energy balance. There is a belief that if a mother is obese, the child will definitely be too! Although the probability is high (80% if both parents are obese, and 40% if only one parent is obese), obesity is not primarily caused by genes, but by the dietary patterns and lifestyle habits that are passed down.

Of course, there is a hypothesis regarding the innate predisposition to obesity—the "thrifty gene" theory, which stems from the body's adaptation to storing energy for periods when food access is limited. Such a metabolism was necessary in prehistoric times when one had to hunt game or gather wild fruits and plant shoots, and meals were infrequent. However, it is currently difficult to determine how many of these primitive genes are active in our genotypes, and this information should be treated more as a curiosity.

We should focus on what we can actually influenceThe very first days in the womb are critical for a child's metabolic health. Research shows that a mother's excessive body weight and poor nutrition during pregnancy promote the development of childhood obesity, insulin resistance, and hypertension. Both excessively high and low birth weights carry significant metabolic risks. Importantly, it is not just the quantity but also the type of food consumed by the mother that influences the child's later taste preferences. Flavors from food pass into the amniotic fluid, where the child becomes accustomed to them and remembers them as pleasant and safe experiences.

Later, during childhood, they are more likely to reach for these foods. As you can see, the formation of eating habits begins from the very first days of life. Children replicate the eating behaviors they observe in those closest to them. At this stage, it is important not to teach children to regulate their emotions with food.

In addition to excessive calorie intake, physical activity plays a huge role in the development of obesity. There are many solutions, such as elevators, escalators, and electric scooters, that reduce our energy expenditure.

Summary

Regardless of the cause of obesity, excess body fat is devastating to our health. Treatment should be started as soon as possible, before the damage becomes irreversible. Treating obesity requires an interdisciplinary approach and multi-directional action. Often, in addition to pharmacotherapy and a balanced diet, support from a psychologist or psychiatrist is necessary. If you are struggling with being overweight and are heading toward obesity, try to stop this process as soon as possible. The most effective method for preventing obesity is a diet based on sound nutritional principles combined with regular physical activity. If a weight-loss diet proves ineffective, the first step should be to verify its caloric content, pay attention to snacking and beverages, and examine your physical activity levels. Next, it is worth performing basic medical tests and nourishing your gut microbiota. Only at the very end should you look for causes in your genes, as the mutations described above are quite rare.

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