Why is my LDL cholesterol increasing?

After being diagnosed with high cholesterol, I increased exercise a bit but changed my diet drastically, nearly following the dietary recommendations to a T. After six months of this, my HDL has risen nicely and triglycerides have gone down a bit, but my LDL has gone up 20 points (about 10%)! Now my total cholesterol is higher than before, and I can't understand why.

To answer this question properly I would need to know what dietary changes you have made, but I reckon I could guess.
We will assume that you have cut back on fats, and as such will have increased carbohydrate intake.

Now to try to understand the mechanisms of the subject of cholesterol.

First and foremost, the measurements are not of cholesterol, they are of Low Density Lipoproteins(LDL) High Density Lipoproteins (HDL) and Very Low Density Lipoproteins (VLDL, but erroneously called Triglycerides). A true triglyceride is three fatty acids attached to a glycerol molecule. Whenever I refer to a VLDL, it is what you know as a triglyceride, which contains a high proportion of triglycerides. Confusing isn't it? And I'm sure that is deliberate.Missing from this list are chylomicrons and Intermediate Density Lipoproteins (IDLs)

A lipoprotein is what carries cholesterol and lipids (fat), in the form of triglycerides, around the body, as they are not water soluble.

When you digest fat in the small intestine they are packed into chylomicrons,along with dietary cholesterol,.Chylomicrons have Appolipoproteins added to the outside which act like identifiers. As this chylomicron travels around the body, cells with the appropriate receptor to the appolipoprotein take the triglycerides from the chylomicron. Once most of the triglycerides are gone, it has become a chylomicron remnant, containing mainly cholesterol and is absorbed by the liver thus delivering dietary cholesterol to the liver. No VLDL (erroneously and confusingly called triglyceride) or LDL in this pathway.

When you consume excess carbohydrates the liver will convert the excess blood glucose into triglycerides (real triglycerides, not VLDL) and pack them into VLDLs, along with cholesterol. It has one different appolipoprotein (identifier) added to it and sent out via the bloodstream.

Again, cells with the appropriate receptor will take triglycerides from the VLDL, which will become a IDL, and as it loses most (true) triglycerides, eventually an LDL, An LDL consists of mainly cholesterol and a few triglycerides. It's function is now to provide cholesterol to the cells that need it.

If no cells need any cholesterol, there will be no cells with the appropriate receptor, and the LDLs remain in the blood.

So in your case, again assuming your carb intake has increased, you are producing more VLDLs (erroneously and confusingly called triglycerides) , but your increase in exercise means that there is more demand for their contents, so they are converted into LDLs. There is however, no increase in demand for cholesterol, so now you have elevated levels of LDLs, yet lower VLDLs (erroneously and confusingly called triglycerides)
HDLs are separate again, and not really relevant to the point I'm trying make
I know this is confusing so to summarise;

Digested fat is packed into Chylomicrons, transferred to cells, and the remnant absorbed by the liver.-Gone from the bloodstream completely
Fat created by the liver , maily due to high blood sugars, Is packed into VLDLs ( what you know as triglycerides) and transferred to cells that need it, thus becoming LDLs.
If no cells need cholesterol, Then LDLs stay in the blood.

The whole idea that lowing fat consumption will lower your cholesterol levels is just plain wrong. No study has ever shown this to be case, and the science shows how flawed this idea is, Literally thousands of people are told to do this, which doesn't work and then end up on cholesterol lowering drugs.

"In Framingham, Massachusetts, the more saturated fat one ate, the more cholesterol one ate, the more calories one ate, the lower people's serum cholesterol...鈥?Dr William Castelli 1992 (Director of the Framingham study, that extensive study of which many contort the results to promote the low fat anti cholesterol ideas)

"The Atkins dieters had significantly greater increases in good cholesterol (HDL) and greater decreases in triglycerides"
http://health.upenn.edu/News/News_Releas...

I challenge anyone who doesn't agree with this to prove me wrong, not just give it the thumbs down. Otherwise you are simply admitting that you too have been conned, but don't have the courage to admit it.

Your doctor would be the best person to answer this. Watch out for sweets though. They can raise your cholesterol too , not just fats.Try some Smart Balance margarine or spread or whatever they classify it as. It helped my cholesterol go down a lot. Oh and watch for white flour items like pasta and white bread. Lay off of them. Drink plenty of water to help flush the excess out . Try a bowl of oatmeal every day. You usually have to have a serving and a half for it to help. Put some smart balance in it. Also they have Smart balance cooking oil for any frying you want to do. Give it a month or two and see if it doesnt help. It helped me.

Calculate your LDL:HDL ratio. That is more important. LDL can be high but safely if you get a lot of healthy anti-oxidants in your diet. With HDL of 80-90 or so, LDL hardly even matters.

Don't exercise at a pace at which you are breathless or even close. Long moderate that you can go and go. Oxidized LDL is the most dangerous variety that contributes to arterial plaque build-up.

My numbers went from 37/137, to 57/87 to 37/57, to 47/61. The first ratio was about 3.5 to 1, the latter ones 1.6 to 1. My doctor is very happy with those. I'm on a very low fat diet for very badly clogged arteries. I get light chest pain for days with ANY fatty meal, so I don't do that. I snack on pistachios occasionally, and that is the most fat I get without pain.