A barbell is an interesting analogy for investing where the investor puts their money in two distinct and different investment types or strategies. Often this is a division of high and low risk investments common for dividing long and short-term investments. For example putting long-term investments in stocks and holding cash for monthly expenses. This division shows up in separating stock investments between taxed and tax-free accounts, in which certain investments make sense in one account or the other.
An interesting question is whether it might make sense to invest some money in more mid-tier investments to both cover expenses and generate more return.
Barbell Life Strategy: http://bitsbusiness.com/life/barbell-for-life/