In partnership with mattress.ng Does body weight affect a mattress? Your body weight does determine how much pressure you place on a mattress which in turn impacts the comfort you get from the mattress. If you weigh 59kg to 104kg, you're a good candidate for a mattress with a medium soft to medium firm. The bed will feel firm enough to support your shoulders, lower back,and hips,but soft enough to cushion and conform to your body. If you weigh more than 104kg, you may want to consider a medium f