Most of us with type 2 diabetes also have problems with lipid levels, both cholesterol and triglycerides. So the following blogposts about diet and lipid levels, written by a nondiabetic/prediabetic software engineer, are relevant to us.
Because the author, Dave Feldman, is a software engineer, his blog is a bit geeky (understatement of the year), and it will probably tell some of you more about diet and cholesterol than you wanted to know. But he's done an incredible number of N=1 experiments on himself, and the results are fascinating.
He's on a low-carb diet, and in a nutshell, he's shown that at least in his case:
1. Cholesterol levels change quickly, in about 3 days, not very slowly as most people will tell you.
2. Counterintuitively, the more fat he eats, the lower his total cholesterol levels go. Also lower triglycerides, LDL cholesterol, and LDL particle number, which some people think is a better marker of cardiovascular risk than LDL cholesterol. HDL levels increase.
3. It's his diet in the 3 days preceding the test that affect the cholesterol levels. Diet on other days doesn't seem to matter.
Note that some people argue that cholesterol levels don't matter. Whether they do or don't, it's interesting to see how quickly they change with the fat content of the diet, which suggests that unless you eat the same thing every day, the lipid values you get with standard testing don't mean a lot.
After testing himself rigorously, Feldman also tested his sister. He says he's a "hyper-responder" to a low-carb ketogenic diet, meaning that when he went low-carb, his cholesterol levels skyrocketed. Although most people see cholesterol levels fall when they go low-carb, Atkins Diet author Robert Atkins had noted that in about 25% of people, cholesterol levels do go up on such a diet.
Feldman's sister, also on a low-carb ketogenic diet, is not a hyper-responder, and he wanted to see if she'd react the same way he did, so they both ate the exact same food at the exact same time of day for a few days. It turned out that although her cholesterol levels were lower, they followed the same pattern: more fat in the three days preceding the test resulted in lower cholesterol levels.
If you want the details, you can find them here:
with more undoubtedly to come.
Feldman says he's planning to write something for the nonengineer.
In the meantime, this suggests that if you're concerned about cholesterol levels that have changed from your last test, it might be worthwhile to see what you were eating in the three days before each of the tests, to see if that could have been a factor.