Rethinking obesity: A call for a more accurate diagnosis, prevention approach

Obesity is a medical condition marked by an excessive accumulation of body fat that negatively impacts overall health. For decades, the Body Mass Index (BMI) has been the primary tool for diagnosing obesity, and a BMI of 30 or higher is generally considered indicative of obesity. However, experts are now advocating for a major rethink of how obesity is defined and diagnosed, challenging the long-standing reliance on BMI as the sole marker.

In a report published in The Lancet Diabetes & Endocrinology, researchers argue that BMI, a simple measure that compares an individual’s weight to their height, does not adequately understand a person’s health, particularly when assessing obesity.

The report proposes a new approach that divides obesity into two distinct stages: preclinical obesity and clinical obesity. Preclinical obesity is when a person has excess body fat, but their organs and bodily functions remain unaffected. In contrast, clinical obesity occurs when excess fat begins to harm vital organs, leading to chronic diseases and complications.

Obesity rates are soaring globally. In 2022, one in eight people globally were living with obesity. The prevalence of adult obesity has more than doubled since 1990, while adolescent obesity has quadrupled. According to the World Health Organization, 2.5 billion adults (aged 18 and older) were overweight in 2022, with 890 million of them living with obesity.

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• Health
• Obesity
• Rethinking obesity: A call for a more accurate diagnosis
• prevention approach

The data reveals that 43% of adults were overweight, and 16% were classified as obese. Additionally, 37 million children under the age of 5 were overweight, and over 390 million children and adolescents aged 5 to 19 years were overweight, including 160 million with obesity. The rising numbers of obesity are largely attributed to sedentary lifestyles and poor dietary habits.

and linked to life-threatening conditions such as heart disease, diabetes, and cancer, BMI fails to account for differences in body composition, such as the ratio of muscle to fat. As a result, an individual with a high BMI may be classified as obese despite having more muscle mass than fat, while someone with a normal BMI might still harbour unhealthy levels of body fat, putting them at risk of obesity-related diseases.

The study emphasizes that adiposity—the amount and distribution of body fat—is a more accurate indicator of obesity-related health risks. Adiposity provides valuable insight into how fat is distributed throughout the body and its impact on organ function. The researchers propose the use of additional diagnostic tools, such as waist circumference (which serves as a proxy for fat distribution) or advanced body scans using low-level X-rays to directly measure fat mass. These methods would offer a more precise and detailed understanding of an individual’s health than BMI alone.

Francesco Rubino, a bariatric surgeon at King’s College London and one of the study’s lead researchers, highlighted the limitations of BMI. Although BMI is widely used for diagnosing obesity due to its simplicity and ease, it fails to assess health risks at the individual level. For instance, an athlete with substantial muscle mass might be classified as obese due to a high BMI, even though they may have a low body fat percentage and no health risks associated with obesity. Conversely, someone with a normal BMI might have high levels of fat, significantly increasing their risk of conditions like heart disease. This misclassification can lead to unnecessary treatments for some and failure to identify others who are at greater risk.

The report also stresses the importance of a more personalized approach to diagnosing obesity, taking into account variables such as age, gender, and ethnicity. Different populations may experience health risks at lower BMI thresholds, making it essential to tailor diagnosis and treatment.

For example, women, particularly those from certain ethnic backgrounds, may face obesity-related health complications at lower BMI levels than men or individuals from other ethnic groups. Louise Baur, a paediatrician at the University of Sydney and one of the co-authors of the study, pointed out that a one-size-fits-all approach to obesity diagnosis is insufficient. Personalized assessments are critical to identifying individuals at risk, even if they fall within the "normal" BMI range.

While BMI remains a useful tool for large-scale studies and population-level research, the report advocates for its use as a screening tool rather than a definitive measure of an individual’s health. Additional metrics, such as waist-to-hip ratio or waist-to-height ratio, should be incorporated alongside BMI to assess adiposity more accurately. For individuals with a BMI above 40, typically indicating a high level of body fat, these additional methods may not be necessary. However, for individuals with lower BMIs, further tests should be conducted to confirm whether excess body fat is present and assess its potential impact on their health.

The study introduces the clear distinction between preclinical and clinical obesity. In the preclinical stage, individuals have excess fat but do not yet exhibit signs of organ damage or dysfunction. These individuals may still have normal organ function and may not experience immediate health problems. However, they are at increased risk of progressing to clinical obesity, where excess fat begins to damage organs and lead to conditions like heart disease, strokes, and kidney failure. Clinical obesity is characterized by dysfunction in organs and tissues, resulting in severe and potentially life-threatening health complications.

The report emphasizes the importance of early intervention for individuals with preclinical obesity to prevent the progression to clinical obesity. For those already in the clinical stage, timely treatment—whether through lifestyle changes, medication, or surgery—is crucial to prevent further organ damage and improve overall health outcomes. Health counselling and monitoring for those with preclinical obesity can help reduce the risk of more severe health complications.

Policymakers must ensure equitable access to evidence-based treatments for those with clinical obesity, recognizing the condition as a chronic illness requiring appropriate care and resources.

Obesity is a significant public health concern in Kenya, with its prevalence varying across different demographics and regions. According to the 2014 Kenya Demographic and Health Survey, 20.5% of women were classified as overweight, and 9.1% as obese.

A study published in the journal Preventing Chronic Disease in 2018 found that approximately one-third (32.8%) of Kenyan women were either overweight or obese.

Additionally, research published in Frontiers in Public Health in 2020 reported that 31.13% of the Kenyan adult population was overweight or obese.

The World Health Organization (WHO) emphasizes that obesity and related noncommunicable diseases (NCDs) are largely preventable and manageable through a series of preventive interventions throughout life. The foundation of these efforts begins before conception and continues through early childhood. Ensuring appropriate weight gain during pregnancy is crucial, followed by promoting exclusive breastfeeding for the first six months and continuing breastfeeding for up to 24 months or more.

For children, encouraging healthy behaviours is vital. This includes promoting balanced eating habits, physical activity, limited screen time, and good sleep. It's also important to limit the consumption of sugary drinks and energy-dense foods while encouraging healthier food choices.

A healthy lifestyle, including a well-rounded diet, regular physical activity, quality sleep, and the avoidance of tobacco and alcohol, is essential. Additionally, reducing the intake of fats and sugars while increasing the consumption of fruits, vegetables, legumes, whole grains, and nuts plays a key role in preventing obesity. Finally, regular physical activity is encouraged for maintaining a healthy weight throughout life.