I suppose this should be in the nutrition forum, but since not too many of us 50+ visit there, this would be appropriate.
I took up cycling 3 yrs ago at 61. I did it for fun and health. I've certainly had a lot of fun, and from the health side I've lost about 15 lbs or so. But I got stuck about 180 lbs. Worse yet, last year I was diagnosed with pre-hypertension and slightly elevated cholesterol. I was also found to have some thickening in my left carotid artery.
I was proscribed a bp med (lisinopril 10 mg) for my bp, but I found that it seems to cause cramping at about 60+ mi with hard work and high temps. Recently my Dr upped the dose to 20 mg. Now my BP runs in the 120s/70s but with summer coming so will the cramps.
My cholesterol was controlled very well with crestor, but the leg pain, fatigue, and sudden twinges in my shoulder muscles got me off that after about a month. Prevestatin came next, but eventually the same symptoms appeared. My Cardiologist suggested high quality red yeast rice, a supplement he is on. That seems to work, but does cause some fatigue.
I really was hoping that riding 150 - 180 mi a week would help these conditions, but after the initial gains at the start, no luck. I've been kinda stuck. Until recently.
I regularly listen to podcasts on a range of topics, and one technology podcast got side-tracked on to a low-carb discussion. To make a long story short, Steve Gibson, a "white hat" hacker and technology guru, has become a low carb proponent a la Atkins, "The Paleolithic Diet" etc. Like most of his other endeavors, Steve is not promoting any product, but offering his experience and his in depth critical analysis of the subject. In reality his "discovery" is nothing new, but his approach is somewhat different since he is not out to sell a book or any products.
To make a long story short, the idea is to eliminate carbs from you diet and force your body into ketosis, a state where it is using fat for energy rather than glucose (carbs.) The theory is that this change in metabolism will cause the fats in you blood to be used readily, keeping your cholesterol low, despite a high fat diet. In addition, this metabolic change causes salt to be processed differently, lowering your bp as well.
From an athletic standpoint, fat metabolism is more "efficient" than glucose metabolism, since it gives off 30% less CO2 into the blood. Hence you will get a higher performance with out getting "winded."
If you want the learn more, check out Steve's health page. http://www.grc.com/health.htm
It lists lots of resources. Be sure to listen to the podcasts. I don't know how anyone as hyper as this guy could ever have a weight problem!