Recently, I had the delightful opportunity to chat with Dr. Robert Lustig at a conference where he delivered the main address. We had previously collaborated on a panel at UCLA in 2022. If you're interested, you can watch his presentation starting at 34:15 here. Dr. Lustig is a renowned expert on metabolism, so I took the chance to discuss my recent post on the lipid energy model with him. He shared a research paper he contributed to, promising it would clear up any confusion. The post below is a summary of that paper, which you can read here. This research brings together four main theories into a single OBS/Redox model of obesity.

The Four Models of Obesity Explained Simply

Energy Balance Model (EBM)

Ludwig, D.S., Apovian, C.M., Aronne, L.J. *et al.* Competing paradigms of obesity pathogenesis: energy balance versus carbohydrate-insulin models. *Eur J Clin Nutr* 76, 1209–1221 (2022). https://doi.org/10.1038/s41430-022-01179-2

Traditionally, this model suggests that gaining weight is mainly about the balance of calories eaten versus calories burned—the old "calories in, calories out" idea. It highlights overeating and lack of exercise as the primary reasons for weight gain. Recent insights, however, show that despite eating less and moving more, obesity rates continue to rise, which this model struggles to explain.

Carbohydrate-Insulin Model (CIM)

This model focuses on how diets rich in processed carbohydrates (like bread and pasta) lead to increased insulin levels, which then promote fat storage and weight gain. These foods cause the body to initially store fat, making you feel hungrier and eat more, which can lead to obesity and related health issues over time.

Reduction-Oxidation (REDOX) Model

https://www.sciencedirect.com/science/article/pii/S2213231721000355?via%3Dihub

Less known, this theory suggests that too much food intake can increase levels of reactive oxygen species (a type of unstable molecule that can react with other molecules in cells), leading to inflammation and fat storage. This model is supported by evidence that obesity is linked to chronic inflammation and oxidative stress.

Obesogens Model (OBS)

Mahapatra, A., Gupta, P., Suman, A., & Kumar Singh, R. (2021). Environmental Obesogens and Human Health. IntechOpen. doi: 10.5772/intechopen.96730

This newer model proposes that certain chemicals found in processed foods, packaging, and pollutants, known as obesogens, disrupt our hormonal balance and encourage our bodies to store fat. These chemicals can even affect how our bodies respond to diet and exercise from a very young age.

A Unified Approach: OBS/REDOX Model

Heindel, J.J., Lustig, R.H., Howard, S. *et al.* Obesogens: a unifying theory for the global rise in obesity. *Int J Obes* 48, 449–460 (2024). https://doi.org/10.1038/s41366-024-01460-3

Building on the insights from these four models, Dr. Lustig and his team introduced the OBS/REDOX model. This innovative approach suggests that chemicals in our environment not only mess with our hormone signals but also increase reactive oxygen species, disrupting the natural ways our bodies manage energy, which leads to weight gain.

In simple terms, the OBS/REDOX model suggests that new chemicals in our environment (emerging in the last 50-70 years) are partly to blame for the ongoing rise in obesity rates. These chemicals interfere with our hormone systems and promote changes that lead to increased fat storage and metabolic issues, including increased inflammation and changes in how our bodies handle fats and sugars.

Conclusion

The OBS/REDOX model integrates all these ideas into one comprehensive explanation, showing how these small chemical factors and hormonal interactions contribute to obesity. This unified model provides a broader understanding of how various factors come together to affect our body weight. More research is needed, but this model offers a promising framework for understanding the complex processes behind obesity.

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A Unifying Theory Explaining the Obesity Epidemic