First 1,000 days shape lifelong obesity risk, explains Qatar Foundation experts

Doha, Qatar: Obesity is increasingly viewed as a complex disease that cannot be attributed to a single cause. Instead, it arises from the interplay of...

Doha, Qatar: Obesity is increasingly viewed as a complex disease that cannot be attributed to a single cause. Instead, it arises from the interplay of genetic, environmental, and lifestyle factors. While genetics are estimated to account for roughly 40 percent of the risk, much of this influence remains unexplained. This gap – known as the “missing heritability” problem – reflects the fact that identified genes account for only a fraction inherited obesity risk.

“While genes are a major factor in obesity, they are not the only one,” explains Dr. Souhaila Al Khodor, Director of the Reproductive and Perinatal Health Division and Principal Investigator, Laboratory of Microbiome and Biomarkers Discovery at Sidra Medicine, a member of Qatar Foundation. “There is polygenic obesity, which results from changes in hundreds of genes; monogenic obesity, caused by a single rare mutation; and a third type, syndromic obesity, which occurs as part of broader genetic disorders.”

So, what explains the gap between expected genetic influence and actual outcomes?

“The explanation may lie in the role of epigenetic modifications and in how genes interact with environment exposures during the first 1,000 days of life – from pregnancy through a child’s second birthday. This critical window can permanently influence how the body regulates energy balance and fat storage, shaping long-term susceptibility to weight gain.”

Dr. Al Khodor emphasizes that the gut microbiome – the trillions of microorganisms in the intestines – plays a central role in nutrient absorption and blood glucose regulation, both critical to obesity. The composition of these microbial communities influences how efficiently energy is extracted from food, how appetite and satiety are regulated, and how inflammatory pathways and insulin resistance develop.