Sunday, May 5, 2019

Retrospective #79: Calorie Restriction and Longevity

When people ask what motivated me to lose so much weight (170 pounds), I reply, “I didn’t want to die; I looked around me and I didn’t see any morbidly obese old people, and I was getting old, and I wanted to live.” As I gained weight over the years, my doctor always urged me to lose. Then, for two visits in a row I was unable to weigh in on his office scale because it only went to 350. So, on the way to work one day in NYC I stopped at the Fulton Fish Market and asked permission to weigh myself on a commercial scale. I was shocked. I weighed 375 pounds. The next week, as I entered my Doctor’s office, he saw me and he said, “Have I got a diet for you!!!I was motivated.
Of course, as I was losing weight on a Very Low Carb (VLC), NOT low calorie, Way of Eating (WOE), I wondered how low I would go. I had the luxury to fantasize about this because, on VLC, I was losing weight easily and without hunger. This will happen when you strictly follow this WOE. I also remember reading about Calorie Restriction (CR) and longevity in Gary Taubes seminal 2007 book, “Good Calories – Bad Calories” (“The Diet Delusion” in the UK). This defining and authoritative work is a tough slog but life changing. Calorie Restriction and its positive association and correlation with longevity are covered in Chapter 13, “Dementia, Cancer and Aging.” Are you motivated yet?
In 2008 the authors of “The Neuroprotective Properties of Calorie Restriction, The Ketogenic Diet and Ketone Bodies,” published as a Public Access, peer-reviewed manuscript, said, “Obesity is associated with an increased risk of dementia.” They continued, “Low dietary energy intake is associated with decreased incidence of Alzheimer’s and Parkinson’s diseases…and calorie restriction for 6 months improves biomarkers associated with longevity including reduced fasting insulin levels, body temperature and DNA damage. Also, “Beneficial effects on mental health have been reported as well, with improved mood following calorie restriction of obese diabetic patients.”
The problem with the preceding paragraph, alas, is that “all the available information is derived exclusively from animal models. Calorie restriction prolongs the lifespan of yeast, roundworms, rodents and monkeys, even when initiated in mid-life.” they said. That tagged-on last clause was the “pearl” for me. It was a really big takeaway.
I’m thinking, hmmmm, “even when initiated in mid-life.” That’s very encouraging. I can reasonably infer from this: It’s not how thin I AM, but what I eat NOW that will determine my health outcome. IT’S NOT TOO LATE!
“To date, however, clinical trials looking at the effects of calorie restrictions on brain aging and neurological disease have not been performed [on humans],” they said. But, the mechanisms to explain the neuroprotective effects of calorie restriction relate to mitochondrial function, oxidative damage to DNA and regulation of gene expression.
In Taubes’ words: “All this leads us back to the spectacular benefits of semi-starvation on the health and longevity of laboratory animals” (GC-BC: pg. 218). “The calorie-restricted animals live longer because of some metabolic or hormonal consequence of semi-starvation, not because they are necessarily leaner or lighter” (ibid. pg. 219).
Taubes sums it up (ibid. pg. 220): “The characteristics that all these long-lived organisms seem to share definitively are reduced insulin resistance, and abnormally low levels of blood sugar, insulin, and insulin-like growth factor (IGF). As a result, the current thinking is that a reduction in blood sugar, insulin and IGF bestows a longer and healthier life. The reduction in blood sugar also leads to reduced oxidative stress and advanced glycation end-products (AGEs) and all the toxic sequelae that follow. The decrease in insulin and IGF also bestows on the organism an enhanced ability to protect against oxidative stress and to ward off other pathogens.” “The most compelling evidence now supporting this hypothesis has emerged since the early 1990s from genetic studies of yeast, worms and fruit flies, and it has recently been confirmed in mice. In all four cases, the mutations that bestow extreme longevity on these organisms are mutations in the genes that control both insulin and IGF signaling.” 
Then, Taubes quotes from the cancer researcher J. Michael Bishop’s 1989 Nobel Prize lecture: “When reduced to essentials, the fruit fly and Homo Sapiens are not very different.” Tomorrow’s Retrospective: Calorie Restriction in humans.

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