It might be easier to just look at it as a pledge to only eat whole/real foods.
I can't remember who I heard said it, but I recall a man saying, "Only eat what your great grandparents would recognize as food".
The simplest foods would be anything that once grew or anything that was killed. Thus, you've got all fruits and veggies and herbs and meat, fish, poultry and game.
You could probably modify this by adding natural spices or sea salt. Sweeteners like maple syrup and honey are natural but a stevia plant might be better as it isn't processed. You could also use dates as a substitute.
Olive oil is a must, I think. Maybe coconut too, though it's more expensive. Vinegar and lemon juice work well for salad dressing.
Smoothies are super easy to make. I have them about 3x weekly. Spinach as a base, plus some parsley and lemon. An apple or orange or some pineapple chunks to break the monotony and a banana will give it that smooth consistency, as will An avocado (but that avocado taste is stronger).
Honestly, for smoothies, besides spinach, parsley and banana, I'll just add whatever fruit I can find on sale that week at the store.
Eating clean/sugar free isn't hard or complicated. It's our habits and emotional attachments to the foods which make the process so difficult. Being a human contains within it both our potential for both success and sabotage lol.
I keep a stash of Welch's fruit snacks and turkey jerky to gnaw on whenever I get angry when I'd honestly be better served by working that aggression out through exercise and not eating. That said, I'm joining the challenge with you
@African Peasant .