Obesity is a global pandemic; prevalence has tripled since 1975 and today an estimated 650 million people are living with obesity[1]. Individuals living with obesity tend to suffer from poorer health outcomes, impacting their ability to work, quality of life, and placing a greater burden on their personal finances, the workforce and the economy]. Obesity is a complex public health issue, and it is vital we refrain from adopting a blanket approach to address it, especially as some groups are impacted more than others[2]. We know that obesity is significantly more prevalent for individuals from socioeconomically disadvantaged backgrounds or ethnic minority groups. We can think about the different socio-economic factors that impact the cause of overweight and obesity like an onion, with many layers addressing the underlying issue which will allow us to tackle health from various perspectives[3]^,[4].

Let’s peel back these layers to understand the factors which contribute to obesity:

1.Individual: 

Individual factors such as, knowledge, attitudes and behaviours can influence risk of living with obesity, in addition to age, race and gender. It is recognised that there is a deprivation gap in obesity, where the prevalence of children living with obesity is twice as high in deprived areas [5]^,[6]. This can be due to unhealthy food outlets being more accessible and affordable. The challenges faced by individuals, especially those in deprived areas, limits their accessibility and affordability to make healthier options.

2.Interpersonal: 

Individuals' interpersonal networks can influence their behaviour and characteristics regarding weight gain and obesity management. For example, family dynamics, friendships, peer-to-peer relationships, and work groups can play a significant role.  Additionally, peers have positive and negative influences, for example, individuals tend to be more active in the presence of their peers, however, they can also experience pressure to choose more unhealthy foods when socialising.  

3. Institutional: 

The following layer explores the relationship between institutions and how they impact access to foods. When considering education or work settings, availability and accessibility of healthy nutritious and affordable food varies. Whilst there may be nutrition standards, these are not always followed or enforced. Weight bias is experienced in education, healthcare and workplace settings which can lead to stigmatising acts. This discrimination takes place in many forms, for example, students can be victimised by their peers and teachers. This, in turn, may lead to bullying, skipping meals or not progressing to higher education. Individuals subject to weight bias tend to have inferior care from healthcare professionals as well as less pay and fewer promotions from employers[7]^,[8].

4. Community: 

Today’s environment is obesogenic, which refers to the influence of infrastructure, neighbourhoods or conditions on the promotion of obesity. The lack of green spaces affects one's physical activity leading to a sedentary lifestyle. Food aggregators, like Deliveroo, were found to promote buckets of fried chicken to poorer postcodes with higher levels of obesity in comparison to sushi which is promoted in more affluent areas with lower levels of obesity. This exacerbates the limited access to nutritious and affordable foods.

 5. Public Policy: 

The final layer includes Government regulations, brought about to bring positive change in the population. For example, the Soft Drinks Industry Levy was introduced in 2018 and successfully encouraged manufacturers to reformulate their products and reduce the sugar content. The levy led to a 29% reduction in the sugar content of soft drinks within three years and no change to the total volume of soft drinks purchased[9]. Other measures include, the promotion of multi-buy offers (buy one get one free) on foods which are high in saturated fat, sugar and salt (HFSS), restricting the display of HFSS food at end-of-aisle. The former policies are examples that address the unhealthy food environment, with the aim to make healthier options available for everyone. 

To effectively improve population health, it is vital to adopt a whole systems approach referring to each layer of the onion where the onus for our health lies on everyone. Implementing policies which address all five layers will effectively help to tackle the root causes and reduce health inequalities. The impact of multi-level policies will not only have a positive effect on public health but also within physical, socio-cultural and political systems.  

Campaigns addressing obesity tend to focus on the individual, but we must look at all contributing factors. This year’s Sugar Awareness Week (14th-20th November) is raising awareness of the negative health implications of consuming excess sugar and calories. Consuming excessive unhealthy food and drinks which are high in sugar (and calories) is linked to weight gain, dental decay and contributes to obesity. We encourage individuals, families, schools, food/drink companies and the Government to act now for the betterment of our population’s health and to make healthy food access a right for all.