At its extreme though, clean eating can be highly restrictive. No gluten, no dairy, no sugar, no coffee, no meat - the rules are many and varied.
Search #cleaneating on Instagram and you'll find 18 million posts, shots of everything from normal-looking dinners to chia-seed puddings.
There are also many, many shots of extreme physiques: women with tiny waists and bubble butts, chiselled men with impossibly buff torsos.
The people appear perfect in their gorgeous activewear and photogenic yoga poses.
They convey a message that you too can be this attractive and happy if you're prepared to "do the work" and have the necessary dietary control. And it's this message that can prove seductive and ultimately harmful to vulnerable people.
Orthorexia describes an obsession with healthy eating. It's not an official eating disorder but health professionals often recognise it as a type of disordered eating behaviour.
It's when a desire to eat healthily tips over into a desire to control the diet to the extent that it interferes with living a normal life. It is most common in young women - who are also heavy users of social media.
It's a sneaky one because it can be masked, as Nigella pointed out, by the appearance of simply "being healthy".
Think about that term "clean eating", though.
The implication is that any other way of eating is unclean, and therefore wrong, that anything we eat that doesn't fit the clean criteria is "dirty" and will need to be atoned for. This is not a healthy way to live.
At this time of year, it is worth remembering that food isn't clean or dirty. It's just food.
It's about nourishment but it's also about pleasure. What we eat (or don't) should never affect how we feel about ourselves, that's giving food too much power.
So smile and enjoy those Christmas foods and let them make you feel nothing but joyful.