Hey Karen. It's the Spudfit challenge by Andrew Taylor. He did one year of potatoes only and lost like 200 lbs (?) He's kept it off and transitioned into coaching and helping others. I am basically going to do 23 days of potatoes only since I will be leaving on the 23rd with my husband for a week in Hawaii. I did a 21 day potato only challenge back in November of 2020 to get off my Covid chub. I lost 35 lbs over the course of about 3 months. I have kept 20 lbs of it off since that time. Check out the link for the spudfit challenge here if you are intersted: https://spudfit.com/