Can Obesity Cause Asthma: The Medical Link and Risks

Introduction

Asthma and obesity are two of the biggest health issues of our time. They may seem unrelated but the evidence is mounting that there’s a strong connection between the two. This article will look into the complex relationship between obesity and asthma, how excess weight can cause and worsen asthma symptoms.

Asthma is a chronic respiratory condition where the airways become inflamed and narrowed resulting to wheezing, shortness of breath and chest tightness. Obesity is defined as excess body fat, usually measured by Body Mass Index (BMI).

As both conditions rise globally, understanding the connection between them is key to prevention and management strategies.

Obesity and Asthma

Obesity as a Risk Factor

Many studies have proven obesity as a risk factor for developing asthma especially in children and adults. Research shows that obese individuals are 1.5 times more likely to develop asthma compared to those with normal weight.

A study published in the American Journal of Respiratory and Critical Care Medicine found that for every unit increase in BMI, the risk of asthma increases by 7% in men and 9% in women. This is why maintaining a healthy weight is key to preventing asthma.

Mechanisms behind Obesity and Asthma

Several mechanisms have been proposed how obesity contributes to asthma development and exacerbation:

Chronic Inflammation: Obesity is associated with chronic low-grade inflammation all over the body. This systemic inflammation can spread to the airways and trigger or worsen asthma symptoms.
Mechanical Effects: Excess weight especially around the chest and abdomen can physically compress the lungs and diaphragm. This compression can result to reduced lung volume and decreased airway function making breathing difficult.
Hormonal Factors: Adipose tissue produces various hormones and cytokines that can affect airway inflammation and reactivity. For example, leptin, a hormone produced by fat cells, is linked to increased airway inflammation.
Oxidative Stress: Obesity is associated with increased oxidative stress which can damage lung tissues and contribute to airway hyperresponsiveness.
Genetic Factors: Some genetic variations may predispose individuals to both obesity and asthma, meaning shared genetic susceptibility.

Impact on Existing Asthma

For those who already have asthma, obesity can worsen symptoms and complicate management. Obese asthma patients experience:

More frequent and severe asthma attacks
Reduced response to standard asthma medications
Decreased lung function
Lower quality of life
Increased healthcare utilization and costs

Asthma Prevalence and Obesity Rates

Global Asthma Prevalence

Asthma affects over 300 million people worldwide, prevalence varies across regions. According to the Global Asthma Report 2018:

1 in 13 people have asthma globally
Urbanized countries have higher prevalence
Asthma rates are increasing in many low and middle-income countries

Obesity Epidemic

Obesity rates are rising rapidly over the past few decades:

1.9 billion adults worldwide were overweight in 2016, 650 million were obese (WHO data)
In the US, 42% of adults were obese in 2017-2018 (CDC data)
Childhood obesity rates have tripled since the 1970s in many countries

Asthma and Obesity Intersection

Obesity prevalence is higher among those with asthma:

In Australia, 35% of adults with asthma are obese, 28% of those without asthma
A study in the US found 38.8% of adults with asthma are obese, 26.8% of adults without asthma

These numbers show the overlap between the two conditions and why obesity should be addressed in asthma management.

Body Mass Index (BMI) and Asthma

What is BMI

Body Mass Index (BMI) is a widely used measure to classify weight status:

BMI = weight (kg) / height² (m²)
Underweight: BMI < 18.5
Normal weight: BMI 18.5-24.9
Overweight: BMI 25-29.9
Obese: BMI ≥ 30

BMI and Asthma risk

A meta-analysis of 7 studies found overweight and obese adults had 38% and 92% increased risk of asthma incidence respectively compared to normal weight individuals.
In children a systematic review found overweight and obese children had 35% and 50% higher risk of asthma respectively.

Limitations of BMI

While BMI is useful, it has some flaws:

Doesn’t distinguish between muscle mass and fat mass
Doesn’t account for fat distribution
Not accurate for certain populations (e.g. athletes, elderly)

Other Measures

Other measures that can give more information on obesity related asthma risk:

Waist circumference
Waist-to-hip ratio
Body fat percentage
Visceral fat measurements

These can give a more detailed picture of how body composition relates to asthma risk.

Severe Asthma and Obesity: A complicated relationship

What is Severe Asthma

Severe asthma is persistent symptoms and frequent exacerbations despite high dose inhaled corticosteroids and additional controller medications. Affects 5-10% of all asthma patients but accounts for a large proportion of healthcare costs and morbidity.

Obesity as a comorbidity in Severe Asthma

Obesity is a common comorbidity in severe asthma, especially in adults:

Up to 75% of patients with severe asthma are obese
Obesity is associated with more frequent and severe asthma exacerbations
Obese patients with severe asthma require higher doses of medication and have poorer asthma control

Mechanisms of Severe Asthma in Obesity

Several factors contribute to severity of asthma in obese individuals:

Altered Lung Mechanics: Excess weight compresses the chest wall and diaphragm, reducing lung volumes and increasing work of breathing.
Chronic Inflammation: Obesity related systemic inflammation exacerbates airway inflammation in asthma.
Metabolic Dysfunction: Obesity is often associated with metabolic syndrome which can worsen asthma symptoms.
Altered Pharmacokinetics: Obesity affects the distribution and metabolism of asthma medication, reducing their effectiveness.
Sleep-Disordered Breathing: Obesity increases the risk of obstructive sleep apnea which worsens asthma control.

Treatment Challenges

Managing severe asthma in obese patients is tough:

Reduced response to inhaled corticosteroids
Increased risk of side effects from systemic corticosteroids
Difficulty in performing lung function tests
Complicating factors such as gastroesophageal reflux disease (GERD) and obstructive sleep apnea

Managing Obesity to improve Asthma Outcomes

Weight Loss Benefits

Weight loss has been shown to improve asthma outcomes in obese patients:

5-10% weight loss can improve asthma control and quality of life
Weight loss can reduce asthma medication
Bariatric surgery in severely obese patients has been shown to improve asthma symptoms and lung function

Dietary Interventions

Effective dietary strategies for weight loss in asthma patients:

Calorie Restriction: A moderate calorie deficit of 500-750 kcal/day is recommended for sustainable weight loss.
Mediterranean Diet: Rich in fruits, vegetables, whole grains and healthy fats. Has been shown to improve asthma control.
Low-Glycemic Index Diet: May reduce inflammation and improve asthma symptoms.
High Fiber Intake: High fiber diets have been linked to better lung function and reduced inflammation.

Exercise

Exercise is key to weight management and also improves asthma control:

150 minutes of moderate-intensity aerobic exercise per week
2-3 times strength training per week
Start slow and gradually increase intensity to avoid exercise induced asthma symptoms
Consider swimming which is well tolerated by asthma patients

Behavioral Interventions

Weight management often requires addressing behavioral factors:

Cognitive-behavioral therapy to address emotional eating and develop healthy habits
Stress management techniques like mindfulness and meditation to support weight loss
Setting realistic goals and tracking progress to improve motivation and adherence

Bariatric Surgery

For severely obese patients with uncontrolled asthma, bariatric surgery may be an option:

Studies have shown significant improvement in asthma control and medication use after bariatric surgery
The choice of surgery should be made in consultation with a multidisciplinary team, taking into account the patient’s overall health and asthma status

Reducing the Risks: Prevention and Management

Early Intervention

Preventing obesity in childhood is key to reducing asthma risk:

Healthy eating habits from an early age
Regular exercise in children and adolescents
Address environmental factors that contribute to obesity, such as access to healthy food and safe spaces for exercise

Integrated Care Approach

Obesity related asthma requires a holistic, multidisciplinary approach:

Pulmonologists, allergists, dietitians and obesity specialists working together
Monitoring of both weight and asthma symptoms
Personalised treatment plans that address both conditions at the same time

Patient Education

Educating the patient is key to management:

Educate the patient about the link between obesity and asthma
Guide the patient on healthy lifestyle choices
Teach inhaler technique and medication adherence

Environmental Modifications

Addressing environmental factors can reduce asthma triggers:

Smoking cessation programs
Indoor air quality improvement
Allergen and pollutant reduction

Future Research

More research is needed to understand and address obesity related asthma:

Investigate the molecular mechanisms between obesity and asthma
Develop targeted therapies for obesity associated asthma phenotypes
Long term outcomes of weight loss interventions on asthma control

Conclusion

The relationship between obesity and asthma is complex and multifaceted. As both conditions rise globally, understanding this connection is crucial for prevention and management strategies.

By addressing obesity through lifestyle changes, dietary interventions and when necessary medical or surgical treatments we can reduce the burden of asthma and improve outcomes for millions worldwide. A holistic, patient centred approach that addresses weight management and asthma control is key to optimal health outcomes.

Keep up to date with the latest evidence and apply it to your practice. We can reduce the burden of both obesity and asthma. Better lives for all.

Resource Links

Global Initiative for Asthma (GINA)
https://ginasthma.org/
This is an international organization that provides up-to-date information on asthma management and prevention. They offer guidelines, reports, and resources for both healthcare professionals and patients.
World Health Organization (WHO) – Obesity and Overweight
https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight
This WHO fact sheet provides global statistics and information about obesity, its health consequences, and prevention strategies.
Centers for Disease Control and Prevention (CDC) – Asthma
https://www.cdc.gov/asthma/
The CDC offers comprehensive information about asthma, including data and statistics, management strategies, and resources for healthcare providers and patients.
American Lung Association – Asthma and Obesity
https://www.lung.org/lung-health-diseases/lung-disease-lookup/asthma/asthma-symptoms-causes-risk-factors/obesity-and-asthma
This page specifically addresses the relationship between obesity and asthma, providing insights into how obesity affects asthma and management strategies.
National Heart, Lung, and Blood Institute (NHLBI) – Asthma
https://www.nhlbi.nih.gov/health-topics/asthma
The NHLBI offers detailed information about asthma, including its causes, risk factors, diagnosis, and treatment options.
The Obesity Society
https://www.obesity.org/
This organization is dedicated to advancing the science-based understanding of the causes, consequences, prevention, and treatment of obesity. They provide resources, research updates, and professional education related to obesity.