Soylent contains plenty of insoluble fiber so digestion is more or less unchanged.

Fiber in Soylent Powder

Total Fiber: 26.98 g

Insoluble Fiber: 2.6 g

Soluble Fiber: 24.38 g

Fiber in Soylent Drink

Total Fiber: 2.85 g

Insoluble Fiber: 2.15 g

Soluble Fiber: 0.7 g

Fiber in Soylent Bar

Total Fiber: 5 g

Insoluble Fiber: 2 g

Soluble Fiber: 3 g

Fiber in Coffiest

Total Fiber: 2.85

Insoluble Fiber: 2.06

Soluble Fiber: 0.79