"...sin entered into the world and death by sin..."

Romans 5:12

Ask Noah as he looks out of the ark, "Does sin bring bitterness?" and he will point out at the surface of the waters and show you the thousands of carcasses and bodies floating atop the flood.

Ask Abraham "does sin bring destruction?", and he will point to the smoke rising from the ruins of Sodom and the pillar of salt that was a woman.

Ask Moses and he will tell you of Korah, Dathan and Abram who the earth swallowed up in that great chasm on the earth.

Don't blame cancer or fat or other things. They are but God's instrument. At the end it is sin that brings true the verse "It is appointed unto man, once to die..."