Over the last few decades we have learnt a great deal about the relationship between genetics, obesity susceptibility and weight loss. In the early years of my career, with the knowledge that I had then, I mistakenly believed that results from a small number of gene variants could determine what diet plan was best suited to an individual, without a practitioner’s input and assessment.
The first company to offer this service was Interleukin Genetics Inc. in the USA, this was in the early 2000’s, but many companies followed suit, including companies I have been involved with in the past. Below is an example of a report from 2009 from Interleukin Genetics from a family member of mine. The recommendations for both the diet and the exercise have been based on only 5 gene variants. We have come a long way!
Through my PhD research and the development of the Advanced Translational Nutrigenomics course, I have had the opportunityto immerse myself in the genetics of weight management and obesity, and it is bar far one of my most favored areas in the nutrigenomics space.In thecourses, I talk about understanding the factors that contribute to weight gain and weight loss resistance. A number of researchers have provided a structure for factors that contribute to weight gain. One of the best papers is by Martínez (Martínez, J. A., & Milagro, F. I. (2015). Genetics of weight loss: A basis for personalized obesity management. Trends in Food Science & Technology, 42(2), 97-115.).Unfortunately, this paper is not open access. Considering Martinez and a number of other researchers, I have developed what I regard as the most important metabolic pathwaysinvolved inweight regulation:
• Cell Regulation
• Metabolism and Adipogenesis
• Thermogenic Processes
• Cytokines, Adipokines and Proteins
• Food Intake, Satiety & Hunger
These processes highlight the complex nature of obesity and weight gain. They also identify pathways that we can work with to understand what gene variants may contribute to the optimal function or dysfunction of the pathway. This provides valuable insight into possible biochemical and metabolic disruption.
The other key principle we teach is that genetics, especially with low penetrance gene variants, should never (and I mean never) be regarded in isolation, and must always exist in the context of who the individual is. This includes diet, weight and medical history, presenting symptoms and dysfunction, epigenetic influences such as diet, lifestyle, exercise, stress, toxin exposure, and importantly, psychosocial influences.
Seen this way, a genetic test by itself cannot and should not determine a single macronutrient-based diet plan. This undermines the complexity of the individual, both genetically and epigenetically, the influence of the gene variants on metabolic processes, and the significant value an expert nutrigenomics practitioner offers their patient in being able to integrate genetic results into their clinic journey and practice.