If I gave you an expandable bag to carry, and added one ounce to it every day, within a couple years you’d be carrying around a 100+ pound bag. Certainly not with ease, but you’d be able to carry it.
That’s what happens when you gain weight over time. You are able to carry it because the gaining so gradual.
The effects can be terrible – insulin resistance, diabetes, skin tags, skin problems, rashes, allergies, bad knees, thin hair, sore back, heavy breasts, thighs chafing, pins and needles in swollen feet, rolls around your belly falling over your waistband – but – you’d still be able to carry it.