Shares of the Franklin, Tenn.-based Tivity Health were up 5.6% to $16.29 in premarket trading Monday.
The transaction is expected to be completed in the fourth quarter.
In December 2018, Nutrisystem agreed to be acquired by Tivity Health for about $1.4 billion. The company also offers the SilverSneakers senior fitness program.
Dallas-based Kainos Capital said in a statement that it has invested more than $2 billion of equity in more than 70 transactions with a total transaction value in excess of $10 billion.
Kainos said it has invested in a number of businesses within the health and wellness space including SlimFast, which it acquired from Unilever in 2014 and sold to Glanbia PLC in 2018.
During Kainos' ownership, Kainos said "SlimFast became the fastest-growing brand in the weight management category at retail for three years in a row."
"Nutrisystem is a valuable partner to its customers, particularly during the Covid pandemic when it is more challenging for many people to access affordable, healthy meals," Andrew Rosen, managing partner of Kainos, said in a statement.
The private capital firm MSD Partners will partner with Kainos Capital in this transaction in the form of a preferred and common equity investment.
During an Aug. 5 conference call, Tivity Health President and CEO Richard Ashworth said "we remain committed to the success of Nutrisystem and are focusing efforts around technology, quality and personalization."