When you transition from a diet with carbohydrates of any kind that come from plants, it is best to start with a simple meal plan. You will be going through a lot of changes. Your gut bacteria that lived off of carbohydrates will die off. Other bacteria will thrive. This may occasionally cause bloating as the bacteria ferment in the intestines.
Don’t be alarmed. It will gradually lessen and disappear completely. If you have not eaten animal fat of any kind for a long time, your gallbladder, which is a muscle that holds the bile to emulsify fat from your diet, will not be accustomed to reacting. It will not send enough bile to the stomach to break down the fat you are eating.
If you have difficulty digesting the fat from the fatty meat you are now eating more of now, you may have diarrhea, cramps, or constipation. Your intestines are unaccustomed to the new ratio of protein and fat. Different enzymes break down grain and vegetables, and other enzymes break down meat.
If your intestines previously had to break down mostly grain and vegetables, you may not have enough of the meat-synthesizing enzymes in your intestines. Fat and protein are broken down first in the stomach. This requires a good amount of acid, which will also be deficient if it hasn’t been required in some time, especially if you have depended on antacids to deal with indigestion all those vegetables were probably causing.
I usually recommend ox bile to improve gallbladder function, betaine hydrochloric acid to help the stomach, and digestive enzymes, such as protease and lipase, to support intestinal function for the first month as you transition. Some people feel better taking easily absorbed magnesium, such as magnesium glycinate if they become constipated.