The speed of weight loss is not a factor in creating loose skin.
First, let's take a look at the anatomy of your skin and the surrounding area. Two layers of tissue reside underneath your skin: adipose (or fat) followed by muscle tissue directly beneath. Both fat and muscle push up against the adjacent layer of skin, keeping it relatively taut before you lose weight.
The issue of loose skin begins long before any weight loss occurs. Instead, it starts when a large amount of weight is gained. When you gain weight, your skin's surface area increases to accommodate the new fat tissue - which is why "stretch marks" sometimes occur.
While your fat cells shrink when that weight is lost, you still retain the same surface area. The new void under the larger surface area creates a layer of skin that may "hang," because there is less tissue underneath taking up space. This is what's known as loose or "sagging" skin.
The amount of loose skin that remains varies by individual. In fact, not everyone's skin sags afterwards, and it depends on several factors: total weight gained and lost, age, total muscle mass, and genetics among them.
Your best guard against loose skin is build up muscle mass to replace that void and exercise adds so many additional benefits beyond your skin. Level 2 is all about engaging your body for exercise with your gut microbiome reset as well as your body running off concentrated, nutrient-dense foods ready to fuel and maximize your workouts!