Hi Ann. Yes..sole source is best. I did Atkins for about a year and a half before Cambridge. Like many, I lost about 15 lbs and was stuck there. I ended up with gout and had to stop. Then I found Cambridge again! While I believe in the low carb lifestyle, I do not follow Atkins or any specific plan. I avoid all grain and sugars including fruit and high carb veg. I now encourage my clients to stick with healthy non-seed oil fats like olive or avocado oil, butter, or animal fats with healthy protein for any added food. No snacking. Just your Cambridge and one small meal if needed.