The regulation change will implement a minimum seat+driver weight of 80 kilograms, or approximately 176 pounds, to compete according to a report from Motorsport.
On its own, the car will need to weigh at least 660kg, a 6kg increase from current standards. The decision was discussed at the last F1 Strategy Group meeting which presented officials with an exact figure. Following further conversation by the Formula 1 Technical Working Group, a finalized proposal will be offered and agreed upon before the ruling goes into effect for 2019.
Driver weight became a concern during F1's V-8 era where teams pushed the limits and encouraged their drivers to lose what some considered an unhealthy amount of heft. The most recent publicized example of this took place between Force India and Sergio Perez when the team asked him to lose weight ahead of the 2017 season, albeit a measly four pounds.
The allowed car/driver weight was bumped to 728kg last season to allow for larger wheels and tires and, after this season, it will yet again step up to 734kg. The additional ~15kg of the now-mandatory Halo cockpit safety device have also been considered.
“It's been a common topic over many years, actually, it's not a fresh point,” Williams technical chief Paddy Lowe told Motorsport. “If you go back, many years, actually, the driver weight was not in the car weight at all. And then it became added somewhere in the mid-90s to the total weight.
"But it's still left, as some perceive—including many of the drivers—a problem around their management of weight, sometimes that can affect them personally in quite a big way."
Officials decided that these new regulations are feasible for the upper limit of modern F1 drivers. The main concern lied with younger competitors who consistently pushed for lower weight, giving them a break in terms of the already-heavy physical demand.