How big should my calorie deficit be?

A 500 cal per day deficit is the standard starting point, producing about 0.5 kg (1 lb) of fat loss per week. Larger deficits (750-1000 cal per day) produce faster loss but increase muscle loss, hunger, and the risk of quitting. Smaller deficits (250-300 cal per day) are easier to sustain but slower.

How long does it take to lose 20 pounds?

At a 500 cal per day deficit, plan for about 20 weeks (roughly 5 months). The first 1-2 weeks will show faster loss on the scale due to water, then settle into 0.5 kg per week of actual fat loss.

Can I lose weight without a calorie deficit?

Fat loss requires a sustained calorie deficit. You can improve body composition (gain muscle, lose fat at the same weight) without scale loss, but to lose actual pounds of fat, you need to burn more than you consume over time.