Short term detox diet / new way of eating / vegan whole foods/ one-ingredient diet

My main question: anyone heard of the one ingredient diet? Have you tried it? Going to have to cook meat for husband but will try to get close to one-ingredient

It’s a bit desperate but in the day after Boxing Day I cut sugars out of my diet again and by nightfall I was committing to a vegan sugar free diet, the next day (today) I gave up coffee (tummy acid problems)
Think that covers it for now

Sugar detox underway tired as hell
Calories <2000 each day
Worked out yesterday

Staying on track 3 days in

I’ve heard of limited ingredient diets as a means to identify potential food allergies. You start with just a few ingredients and then start adding back in more ingredients over time.