Obesity and cancer third most important risk factor for cancer in the United States, just behind tobacco and diet (see Figure). Obesity is the source of about 15% of all preventable cancers. In 2018, Chinese researchers performed a systematic review and comprehensive quantitative meta‐analysis of cohort studies reporting body mass index (BMI) and the risk of 23 cancer types, providing epidemiological evidence supporting the association between BMI and cancer risk. The strongest positive association between BMI and cancer risk was found among patients in North America. The mechanisms by which obesity may increase the risk of cancer are not well understood, but it
Degrees of freedom (physics and chemistry) capacity. This is because these degrees of freedom are "frozen" because the spacing between the energy eigenvalues exceeds the energy corresponding to ambient temperatures (). In the following table such degrees of freedom are disregarded because of their low effect on total energy. Then only the translational and rotational degrees of freedom contribute, in equal amounts, to the heat capacity ratio. This is why = for monatomic gases and = for diatomic gases at room temperature. However, at very high temperatures, on the order of the vibrational temperature (Θ), vibrational motion cannot be neglected. Vibrational temperatures are between 10 K