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Medical professionals define obesity as a complex and long-lasting disease, influenced by a variety of factors, including genetics, hormones, behaviour, and our surrounding environment.
The image is a model
Most will be familiar with the role physical activity levels, diet, alcohol consumption, and other existing medical conditions can play,2 but at what point does obesity become a disease? And is it plausible for someone with a normal weight to have obesity?
In this article, we look beyond the weighing scale to understand when excess weight becomes a disease.
40-80% of our weight may be determined by genes
Every person is unique, and this uniqueness can be understood and measured by ‘phenotypes’. Unlike its genetic counterpart, 'genotype', a phenotype is a visible trait, such as the colour of your eyes and hair or your height. It even extends to behavioural characteristics like the way you walk or talk. While our genes lay the foundation for these traits, the environment in which we live plays a significant role in shaping them.
Consider identical twins. Genetically, they share the same DNA, yet one may develop obesity while the other does not. This highlights the interplay of genes and the environment.
People living with obesity are not all alike. Our bodies react differently to our environment, leading to different 'obesity phenotypes'. This diversity can be seen across different populations, with certain obesity phenotypes more frequent in specific regions. For example, while abdominal obesity (excess fat focused around the stomach) is prevalent in South Asia, other areas of the world may have different dominant obesity phenotypes. Diversity is also evident between men and women. For example, women are more likely to store peripheral fat around their buttocks, hips, and thighs than men.
Obesity is often associated with metabolic issues, which are problems with the processes in your body that convert the food you eat into energy and other compounds necessary for survival. These issues can include high blood pressure, high blood cholesterol and blood sugar levels, insulin resistance, widespread inflammation, and low levels of “good” fats. However, individuals with obesity may not always have metabolic issues, and individuals with a normal weight may not always have healthy metabolic responses.
Obesity phenotypes can affect how individuals with obesity experience
the disease and significantly influence the onset of other diseases or
conditions associated with obesity. For example, those living with
obesity and unhealthy metabolic responses may be more prone to mental
health issues, such as depression, than those living with obesity but
have healthy metabolic responses.
Studies have shown that many people with certain mental health conditions are living with overweight or obesity. Specifically
25-60% of those with bipolar disorder,
30-70% with schizophrenia, and
20-50% with depression.
As we learn more about obesity, the more we understand that it is a distinctly diverse disease. There is no ‘one-size-fits-all’ approach to obesity; by moving away from the simplistic BMI classification of obesity towards a more individualised approach, treatment approaches and weight management programmes can be better tailored to an individual’s phenotype for greater health outcomes.
In a recent study, treatments guided by phenotype resulted in notably higher weight loss after one year. A staggering 79% of those treated based on their phenotype lost more than 10% of their weight compared to only 34% in a non-phenotype guided group.
Obesity research is constantly evolving, and as our understanding develops, so does our ability to address it effectively. This article is just a snapshot of the vast and complex topic of obesity phenotypes to help you understand your weight in more detail. If you want to learn more about obesity phenotypes, please consult your healthcare provider.
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