Rapid weight gain may be due to lifestyle changes such as quitting smoking. However, it may also indicate an underlying medical condition, such as kidney disease, insomnia, and cirrhosis. Many people ...

Adam Hayes, Ph.D., CFA, is a financial writer with 15+ years Wall Street experience as a derivatives trader. Besides his extensive derivative trading expertise, Adam is an expert in economics and ...

Psychology Today's online self-tests are intended for informational purposes only and are not diagnostic tools. Psychology Today does not capture or store personally identifiable information, and your ...

Julia Kagan is a financial/consumer journalist and former senior editor, personal finance, of Investopedia. The ability-to-pay principle underpins tax systems by requiring individuals to contribute ...