How Obesity, Sedentary Behaviour and Inflammation Create a Harmful Cycle

Obesity is a chronic, multifactorial disease that involves far more than carrying excess weight. Physical inactivity, inflammation, insulin resistance, declining fitness and reduced muscle mass can be interconnected, creating a cycle that is difficult to break.

This does not mean obesity results solely from a lack of exercise. Genetics, diet, sleep, hormonal, emotional, social and environmental factors all contribute to the process. Even so, becoming more physically active and spending less time in sedentary behaviour are important measures for restoring metabolic and functional health.

Here are some of the ways obesity can create a cycle that harms health.

1. Sedentary behaviour can trigger a cycle of declining fitness

Spending long periods sitting down and making limited use of the muscles reduces the stimulation needed to sustain strength, fitness and metabolic efficiency. Over time, the body may become less able to cope with activities that once felt straightforward, creating an extra obstacle for those wanting to begin exercising.

Moreover, sedentary behaviour and doing no exercise at all are not necessarily the same thing. A person may walk for a few minutes during the day yet remain seated for many hours. Reducing sedentary time must therefore also form part of the strategy.

“Sedentary behaviour contributes to the obesity and inflammation cycle because it reduces energy expenditure as well as the muscle’s ability to take up glucose and use fat as an energy source. Over time, this promotes insulin resistance, loss of fitness and fat accumulation, especially around the abdomen,” explains Dr Guilherme Moury Fernandes, a sports and exercise physician.

2. Visceral fat may drive an inflammatory process

Adipose tissue is not merely an energy store. When there is excess fat, particularly around the abdomen, this tissue can undergo metabolic changes and contribute to the release of inflammatory mediators. The process is linked to changes that extend beyond what the scales show.

Chronic low-grade inflammation can affect several tissues and contribute to metabolic, muscular and joint problems. According to Dr Fernando Jorge, an orthopaedic specialist working in regenerative medicine and interventional treatments, its effects can also be felt in the musculoskeletal system.

“Obesity promotes a state of chronic low-grade inflammation. Adipose tissue releases adipokines and pro-inflammatory cytokines, which may accelerate cartilage degradation, worsen osteoarthritis, promote tendinopathies and contribute to persistent pain. Reducing excess body fat helps lower these inflammatory mediators,” he says.

3. Inflammation is also linked to metabolic changes

Inflammation caused by excess fat does not occur in isolation. It may be associated with insulin resistance and other metabolic changes that make it harder for the body to function properly. The result can be a combination of tiredness, reduced physical capacity and difficulty maintaining an active routine.

Dr Sara Abrão, a gastroenterologist and endoscopist, highlights that visceral adipose tissue has metabolic functions that can affect different systems in the body. “Visceral adipose tissue is not simply an energy deposit. It produces inflammatory substances and may promote insulin resistance, hormonal changes and stimulation of cell multiplication. This is why excess weight is linked to different tumours of the digestive system.”

The relationship between obesity and cancer is multifactorial and does not mean that excess weight determines whether a tumour will develop. Family history, genetics, age, diet, alcohol consumption, smoking and other factors also influence an individual’s risk.

4. Loss of strength can make exercise even harder

When someone with obesity goes for long periods without suitable training, strength and fitness may decline. Joint pain, metabolic changes, poor sleep and associated illnesses can worsen the situation.

Dr Guilherme Moury Fernandes notes that carrying a heavier body also requires greater effort to perform everyday movements. As a result, an activity that is simple for one person may be far more challenging for another, increasing the tendency towards inactivity.

“There is also what is known as sarcopenic obesity, characterised by the combination of excess fat with reduced muscle mass or, more importantly, reduced muscle function. The most significant sign is not simply muscle appearance, but loss of strength, mobility and independence,” he explains.

Assessing functional capacity may therefore be more relevant than considering weight alone. Difficulty climbing stairs, getting up from a chair, walking short distances or carrying objects are signs that deserve attention.

Exercise can help break the cycle, but it must be gradual

Returning to physical activity does not have to begin with intense workouts. For sedentary people or those with physical limitations, lower-impact activities such as walking, cycling, swimming or adapted exercises can provide starting points, provided they are compatible with the person’s clinical condition.

Strength training also plays an important role because it helps preserve or increase muscle mass and strength. The aim should not simply be to cause weight loss, but to improve functional capacity and health markers.

“Resistance exercise, such as weight training, brings a fundamental benefit: preserving or increasing muscle mass, strength and quality. This matters because muscle is one of the main organs responsible for blood glucose control and maintaining functional independence,” says Dr Guilherme Moury Fernandes.

In the specialist’s view, progress must respect each person’s condition. Someone who is very unfit may begin with just a few minutes of activity, then gradually increase its duration, frequency and, later, intensity. “Weight loss should not be the only measure used to assess the outcome of exercise. Improvements in blood pressure, blood glucose, fitness, strength and waist circumference already represent a meaningful health gain.”

The obesity cycle can be interrupted

The relationship between obesity, sedentary behaviour and inflammation can operate as a vicious cycle: lack of movement encourages loss of fitness and metabolic changes; excess fat may contribute to an inflammatory state; pain and reduced physical capacity can make exercise more difficult; and lower activity, in turn, sustains the cycle. Treatment should therefore not be limited to the scales. Restoring strength, mobility, fitness and metabolic health is part of a broader approach to obesity.

The process does not need to start with major changes either. Spending less time seated, progressively moving more throughout the day and beginning an exercise programme suited to the individual’s condition can already be important steps. Where cardiovascular disease, diabetes, uncontrolled high blood pressure, sleep apnoea, significant pain or symptoms such as shortness of breath, chest pain, dizziness or fainting are present, medical assessment should come before progressing exercise.

By Sarah Carvalho