Obesity associated with worse outcomes in younger people hospitalised with COVID-19 in the US
A study from researchers at Johns Hopkins who noted higher rates of obesity in younger patients in the US compared to previous reports from China and Italy has reported reduced mortality with use of anti-coagulation treatment (AC).
The current study included 265 people (58% male) in intensive care units at five hospitals in New York, Florida, Pennsylvania, Cincinnati and Washington and limited results were published in a letter to the Lancet. 
The median BMI was 29·3 kg/m2, with only 25% of individuals having a BMI of less than 26 kg/m2, and 25% exceeding a BMI of 34·7 kg/m2.
In multivariate linear regression analysis, there was a significant association between body-mass index (BMI) and age in patients with COVID-19 in which younger individuals admitted to hospital were more likely to be obese (r2 = 0.051, p=0.0002).
The researchers also noted that obesity can restrict ventilation by impeding diaphragm excursion, impairs immune responses to viral infection, is pro-inflammatory, and induces diabetes and oxidant stress to adversely affect cardiovascular function. [2, 3]
The evidence supporting additional risk from obesity and high BMI in people diagnosed with COVID-19 (currently at around ten studies) are also summarised in a useful short report by the International Severe Acute Respiratory and Emerging infection Consortium (ISARIC). 
- Kass DA et al. Obesity could shift severe COVID-19 disease to younger ages. Lancet. doi: 10.1016/S0140-6736(20)31024-2. (4 May 2020).
- Honce R et al. Impact of obesity on influenza A virus pathogenesis, immune response, and evolution. Front Immunol. 2019; 101071. (10 May 2019).
- Afshin A et al. Health effects of overweight and obesity in 195 countries over 25 years. N Engl J Med. 2017; 377: 13-27. (16 July 2017).
ISARIC Rapid Review team. Obesity: An independent risk factor for COVID-19 severity? (9 April 2020).