Can I ask what symptoms you get when you don't ease your system in to it?
Symptoms vary depending on what else I've eaten within 10 hours of eating the fat, and how active I am. Common symptoms include stomach ache, loose stools, stools that are very green or yellow, or a general feeling of fatigue as my body adjusts to getting a lot more calories than normal from fat instead of from a balance of carbs, protein and fat. The fatigue is especially prominent if I am very active that day, such as doing CrossFit workout a few hours before or after eating the fat or within a couple days of getting most of my daily calories from fat.
1-2 ounces of fat is actually a lot of fat. When you consider how calorie-dense fat is, one ounce of pure fat is usually around 250 kilocalories, and two ounces is around 500 kilocalories. That's a lot of calories to eat at one sitting, no matter what food you're eating. Now granted, suet and back fat aren't 100 percent fat, there's some connective tissue there and some water, but these foods are still extraordinarily calorie-dense so they are very different for your body to process than if you were to eat a large serving of salmon or a leaner red meat like steak that happened to have some fat along its edges or was heavily marbled.
To give a sense for how I balance my meals to avoid feelings of fatigue, when I incorporate raw suet or back fat into a meal so as to achieve the 40-30-30 ratio that seems to work well for me (basically a raw Zone diet, where 40 percent of calories come from raw carbs, 30 percent from raw protein, 30 percent from raw fat), this usually involves just adding 3-5 grams (
not ounces) of pure raw fat. This is a small amount, since it takes 28 grams to make an ounce. Realize that other ingredients in a meal, such as raw meats of various sorts and certain raw fruits (like avocados or olives, both of which I like), also contribute fat.