Large-scale genome-wide association studies have identified 12 genetic loci that are robustly associated with body mass index (BMI).

However, effect sizes of the risk alleles were very small, ranging between 0.058 and 0.329 for BMI and between 0.094 and 0.866 kg for weight. On average, each additional risk allele was associated with an increase of 0.149 in BMI.

All of the genetic loci combined explained just 0.9 percent of BMI variation. Their predictive value for obesity risk is limited.