Did you only drink the shake or also take the supplements? Sometimes the supplements or their fillers can make one feel sick.

Or you could be intolerant of whey; I am. Milk thistle & B-vitamins also make me feel sick.

Spreading things out can reduce the feeling of sickness and help you determine what is causing the problem.

It was only the shake, my husband had one and he was fine. I added Leucine as it said in the recipe. I so want to make this diet work but can't face a whole day of sicky bloatedness. Not sure what to do next - maybe try low carb without the shakes?

Did you try whole egg protein powder instead of the whey?
Some people develop an allergic reaction to dairy of all kinds.

I do all right with smaller amounts of whey. Between that post and now--one summer I did sort of a modified version with frozen "pudding"--whipped three or four eggs with a couple of scoops of whey protein, then froze it, had this two or three times a day for a few months. In the beginning was frying it up as a pancake (sweet enough to eat without any topping). I eventually got tired of the pudding, but I tolerated it well.

Reading back through the thread--I said the six-week cure was the jump off point for the next fifteen pounds of weight loss. Well, it sort of was. But it didn't last. Bit of water under the bridge since then. I've lost with higher protein lower fat a number of times--but eventually rebounded. My longest successful maintenance at the mid-150s pound weight range is the last several years, including now. I found emphasizing fat, keeping to a fairly ketogenic ratio, helped. Starting a fairly active full time job also helped--I don't think it's just the calories burned, but the structure it gives to my days makes it easier to stay on plan (I was always low carb before that, for over a decade, I mean it makes it easier to stick to more specific protein/fat goals as opposed to eating whatever low carb foods I want).

One year after losing down to 154 pounds, I found I had a tendency to binge--on things like honey, or maple syrup right out of the bottle. Or if I bought a jar of peanut butter, I'd eat a tablespoon one day, another the next--but eventually I'd eat most of the jar in a sitting. Or a pound or more of nuts. I got curious about what the 4:1 diet for epilepsy was like--I tried it and found it stopped the binges in their tracks. My current diet isn't quite so stringent, but I do go towards a higher fat ratio.

You can get lots of answers from the Protein Power thread called Middle Aged Middle that ended in 2016. If you have the time, read through all 54 pages - I did and it was an eye opener.