A few reasons:

- If you made a dietary change (e.g., more fiber and less saturated fat), the tests tell you whether it actually worked.

- Statins are dosed based on the LDL or ApoB reduction you need. The most powerful statins cut cholesterol by 50%, but at higher doses the risk of side effects does go up.

- Other medications like PCSK9 inhibitors and ezetimibe exist, and whether to use them depends on the other numbers. For example, PCSK9 inhibitors have a secondary benefit of lowering Lipoprotein(a), and statins and GLP-1s have a secondary benefit of lowering inflammation.

- If blood pressure, HbA1c, etc is high, then there's a slightly different set of diet advice and a very different set of medications. For example, lowering blood pressure through diet is mostly about reducing sodium and increasing potassium.

Behavioral changes can only do so much to lower ApoB. It is a meaningful marker and may trigger additional workup. It may also signal that you should at least consider a statin.

ApoA is completely out of your control and will not change with behavioral modification.

So, no, you're incorrect that these tests are superfluous and all you need to say is "diet and exercise". Besides, even if that was always the answer to these results, you should still have a baseline to see if behavioral modification is doing anything.

"Why not just skip the HbA1c tests? After all, you know they'll give you insulin. Just start taking it."

Do you think everyone with poor blood test indicators is aware of how unhealthy they are? How quickly they need to reverse course? Or do think there might be some possible validity to discussing your results with an actual doctor and understanding how acute your symptoms actually are? Do you think there are no side effects to statins and everyone should just be on one at all times, forever? Do you think there might be some value, for those patients, in discussing GLP-1s? Or nah, everyone can just like, go run 10 miles tomorrow because some 20 year old in SV said so?

I'm always deeply confused by people who think all medicine is "just repeat whatever ChatGPT said as if it's profound, like, duh - I'm smart and invincible and can't quite figure out that other people aren't me", in spite of them not knowing anything about medicine in the first place.

Because for the same behavior, risks are going to be very different on the other side. In my family, for instance, we need significant interventions to get a reasonable risk due to all the bad genetic factors. In my wife's family, not so much. So knowing how serious the risk seems much better than just handing statins to absolutely everyone.

Because everyone's heard that advice, but people don't tend to take action until they have evidence that they, personally, are at risk.

Because I’ll know how much I can slack off.

apob and lpa i believe are relatively stable even outside of diet.

Because people are lazy enough that they will pay money to be told they need to stop being lazy lmao