BMI is one of many ways to assess weight. If a person has concerns about their weight or health they should discuss them with their physician.
* Disease risk Relative to Normal Weight and Waist Circumference for type 2 diabetes, hypertension, and CVD.
References (2/27/2019):
1 https://www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmi_dis.htm
2 http://www.ox.ac.uk/news/2009-03-18-moderate-obesity-takes-years-life-expectancy
3 https://onlinelibrary.wiley.com/doi/full/10.1038/oby.2004.243