I came to a similar conclusion about limited diet causing weight loss. I moved to a small remote town in Europe a few months ago and lost my excess weight with no effort, after having lived in large North American cities all my life. I shop mostly at a local mini grocery store that has limited stock, so my diet tends to be boring and my appetite small. As soon as I stock up from a supermarket with a variety of yummy unusual foods, I start gaining weight.
I don't limit myself to 7 ingredients though. Rather, I eat the same thing for lunch everyday, and rotate through a handful of simple recipes for dinner. This also keeps my IBS-like symptoms under control, but I don't know if my GI is happy due to the ingredients themselves, the lower volume of food, or the fact that it isn't exposed to novel foods as often. Or a combination.
I had severe fibromyalgia/chronic fatigue syndrome for a couple of years, as diagnosed by two independent rheumatologists. It was so bad I couldn't sleep at night and I couldn't get out of bed during the day. Around that time, a few pilot studies came out of Spain with excellent results from CoQ10 supplementation. I had had little success with the regular prescriptions, so I decided to give CoQ10 a try. I felt much better after a week. Eventually I also started supplementing with other stuff known to be used by mitochondria, and 6 months later, I was back to my old self.
I spoke to my rheumatologist about how well I was feeling since taking the supplements. This guys was supposed to be one of the experts on fibromyalgia. He just laughed at me and said that these supplements were nonsense. I tried showing him the pilot studies but he wasn't interested AT ALL.
I continue to wonder what I could have done differently to make this doctor give me the benefit of the doubt and hear me out. In case something like that ever happens again.