I have been conducting my own scientific study with a participant of one, and probably using very questionable research methods.
This is primarily for me, so I can go back and look at it. However, it would be interesting to find out if other people have had similar results.
Here’s what I have figured out (in the second person but it does apply to me).
You can eat whatever you want and control your blood sugar while on the pump. You also gain weight when you do that, and it doesn’t take much to push the envelope on controlling your blood sugar. You have to constantly track your corrections and blood sugar because eventually your TDD (Total Daily Dosage) of insulin will go, causing your carb ratios and/or basal rates to go up.
If you drop carbs you will drop insulin usage. Dropping carbs can often stabilize blood sugar, at least it does for me.
If you exercise, you will drop insulin usage. Strength seems to drop basal rates for me over a long term. I have stopped strength training occasionally and see my basal rates rise.
Cardio exercise only affects blood sugar temporarily. However, doing it every day, drops blood sugar and insulin usage every day.
Too much fat and too much protein does affect blood sugar levels and does affect weight loss. Just not as much.
When I am able to drop insulin usage down to a certain amount, I tend to lose weight. If my insulin usage is higher than a certain amount, I tend to gain weight. Weight gain tends to be faster than weight loss.
When I do drop insulin dosage, I tend to be able to decrease carb to insulin ratios. It tends to take several weeks to stabilize the insulin dosage, and I tend to go low then. It’s important to test more often, sometimes hourly to prevent the low.
By the way, you can’t play these games as easily with injections. In particular, you can’t fix the basal rate as easily — nor can you fix lows as easily. When I get the starts of a low (I try hard not to go low enough to be truly low), I turn on the temporary basal AND do two lifesavers. With shots, you have to wait until the next day, decrease the dosage and then correct all day.