How insulin controls aging

Cynthia Kenyon lectures online

If you want to see Cynthia Kenyon explain how the insulin-signaling pathway controls aging -- and how we know that the insulin-signaling pathway controls aging -- you might want to take about an hour and a half to watch her lecture on the subject.

An Evolutionarily-Conserved Regulatory System for Aging

The Regulation of Aging by Signals from the Reproductive System, and, also, a Link Between Aging and Tumor Growth

In these lectures Kenyon shows that caloric restriction slows aging by regulating insulin and IGF-1 receptors. But she doesn't go for it herself; in an interview in New Scientist (I want to live forever) she says "I tried caloric restriction just for two days but I couldn't stand it, being hungry all the time."

As reported in PLOS Biology (Methuselah's Mould), she also did an experiment where she found that feeding sugar to the worms shortened their lifespans. As a consequence, she chooses to eat a low carbohydrate diet:

“I'm on a low-carb diet. I gave my worms glucose, and it shortened their lifespan. [The diet] makes sense because it keeps your insulin levels down,” she says.

She adds:

No desserts. No sweets. No potatoes. No rice. No bread. No pasta. “When I say ‘no,’ I mean ‘no, or not much,’” she notes. “Instead, eat green vegetables. Eat the fruits that aren't the sweet fruits, like melon.” Bananas? “Bananas are a little sweet.” Meat? “Meat, yes, of course. Avocados. All vegetables. Nuts. Fish. Chicken. That's what I eat. Cheese. Eggs. And one glass of red wine a day.”

In the New Scientist article interview she said:

I eat a diet that keeps my insulin levels low. So, for example, at breakfast I have bacon and eggs with tomatoes and avocados. It's bit like the Atkins diet. I don't actually know if I eat fewer calories, but I feel great and I weigh what I did in high school. I certainly wouldn't want to be hungry all the time, but I'm not, I'm never hungry.

By 2004 Kenyon had eaten a low-carb diet for two-and-a-half years. She reports very good results:

“I have a fabulous blood profile. My triglyceride level is only 30, and anything below 200 is good.....Plus, I feel better. Plus, I'm thin—I weigh what I weighed when I was in college. I feel great —you feel like you're a kid again. It's amazing.”

Kenyon feels angry about the general lack of nutritional knowledge:

“It's a little bit embarrassing to say that scientists actually don't know what you should eat…. We can target particular oncogenes, but we don't know what you should eat. Crazy,” she says.

I will second that.

Addendum:

Stephan Guyenet has an excellent discussion of What's the ideal fasting insulin level? in which he notes that Kitavans have very low fasting insulin without eating a low carbohdyrate diet. Frasseto et al also found that a paleo diet containing ~250 g carbohydrate per day from fruits and vegetables reduced fasting insulin to very low levels within just 10 days (Metabolic and physiologic improvements from consuming a paleolithic, hunter-gatherer type diet). Thus, it appears possible to eat a large amount of carbohydrate from fruits and vegetables (including tubers) and still obtain a low insulin level.