"[there exists] ... the widely held belief that Black people are given to excess and have poor impulse control concerning both sex and food, a myth that continues to inform anti-Black and anti-fat attitudes and policies. In this way, and many others, purity culture and diet culture are indeed siblings. They are the offspring of colonialism and capitalism, and shame is integral to them both. Diet culture attaches morality to food as a way to police the way people eat and to bring bodies under colonial and capitalist control. Purity culture attaches morality to sex to do the same. Beneath it is the assumption that sex will inevitably occur and that everyone desires it. In fact, that assumption is an essential part of purity culture -- the idea that we are all 'sinners' continually battling sexual urges, and resisting those urges until we are bound in heterosexual marriage 'ordained by God' is what makes us pure. It doesn't seek to hinder people from ever having sex at all; it seeks to control the conditions under which people do have sex."
~"Refusing Compulsory Sexuality: A Black Asexual Lens on Our Sex-Obsessed Culture" by Sherronda J. Brown (emphasis is mine for easier reading + highlighting points)