Does Fast Food Make You Fat Or Is It In Your Genes?

People say that when it comes to your weight, you are what you eat. However, according to researchers at UCLA, you’re not just what you eat but also who you came from. A study has shown that your wellness and body-fat responses in relation in fast food are determined largely by your genes, several of which control these responses.


The study is innovative as it is the first to use mice to closely model what would likely happen in human populations. This is because researchers detailed metabolic responses to a high-fat, high-sugar diet in a large and diverse mouse population under defined environmental conditions, and found that your degree of obesity is only modestly accounted for by the amount of food you consume.


According to first author Dr. Brian Parks, a postdoctoral researcher at the David Geffen School of Medicine at UCLA, ‘Our research demonstrates that body-fat responses to high-fat, high-sugar diets have a very strong genetic component, and we have identified several genetic factors potentially regulating these responses’. He emphasised that the team ‘found that obesity has similar genetic signatures in mice and humans, indicating the mice are a highly relevant model system to study obesity. Overall, our work has broad implications concerning the genetic nature of obesity and weight gain’ as prior to this research obesity has largely been connected to environmental factors such as diet and lifestyle.


For the study, which lasted 2 years, researchers placed mice on a normal diet for 8 weeks, and then switched them to a high-fat, high-sugar diet for 8 weeks, measuring obesity traits, fat tissue, global gene expression and intestinal flora, which are normal intestinal bacteria. Parks said ‘We measured the change in fat dynamically, at five different points following a high-fat, high-sugar feeding, providing strong evidence for a genetically controlled body-fat set-point’ as the team identified 11 genome-wide ‘regions’ associated with obesity and fat gain due to high-fat, high-sugar intake, several of which overlap with genes identified in human studies.


Principal investigator Dr. Jake Lusis, a professor of medicine and human genetics and of microbiology, immunology and molecular genetics at the Geffen School of Medicine added ‘We observed high heritability of about 80% for body-fat percentage across the study timeline’ as well as ‘highly heritable’ changes in body-fat percentage after high-fat and high-sugar consumption, ‘suggesting that dietary responses are strongly controlled by genetics.’


Parks concluded that future studies will ‘focus on specific, identified genetic factors and their role in dietary interactions and obesity’ as well as ‘the development of metabolic syndrome and diabetes after high-fat, high-sugar feeding’.

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