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Eat less, live longer

People have been searching for a miracle food for generations. It turns out, the key to longevity might just be what we’re not eating and drinking. Fasting and calorie restriction have been gathering the attention of researchers who think that limiting our intake might be the key to a longer, healthier life.


The Theories

Scientists have theories as to why eating less might help us live longer.

  1. One theory is that by not metabolizing as much energy, our body creates less reactive oxygen species, or ROS, which cause damage to our cells.
  2. Another theory is that eating less causes less Insulin-like Growth Factor, or IGF-1, to be made, telling the body to stop growing and reproducing and to start focusing on maintenance and repair [i]. These and other metabolic pathways most likely work together to explain why caloric restriction, without malnutrition, has been shown to extend the lifespan.


Anecdotal and Scientific Muses

Our first clue comes from pockets of the globe where people live longer than anyone else. On Okinawa Island in Japan, more people live to 100 than anywhere else in the world. Studies of their diets showed that inhabitants at about 1/3 fewer calories than the average Japanese, and they had ~35% lower rate of mortality from heart disease and cancer [ii].

Researchers at the Longevity Institute at University of Southern California also showed in a controlled study that short-term periods of near-fasting, or 5 consecutive days of eating about 50% of a normal diet once a month for 3 months, can have lasting beneficial effects on aging, heart disease, diabetes and cancer [iii]. Protein might even have an effect. Eating a high protein diet is associated with increased risk of dying from diabetes, cancer or any cause in people younger than 65 [iv].  (For older adults, protein is protective because it’s at this age that we start losing lean body mass, and protein helps to prevent this loss.)

A study of people who actually practice some form of calorie restriction in real life showed health benefits as well. These calorie restricting (CR) people ate about 1,100-1,900 kcal per day [v]. The study compared the CR group to a group of matched, average Americans. The people who ate less weighed less, which makes sense. But more incredible was that their blood tests of cholesterol, triglycerides, C-reactive protein and blood pressure put their cardiovascular disease risk at the same level as kids and teenagers.

The most striking part is that the people practicing calorie restriction had average risk factors before they started, and it only took about a year for them to become metabolically youthful.

Think you can run off the pounds and have the same fountain of youth effect? While exercise has also been shown to extend lifespan, studies in mice have suggested that calorie restriction has it’s own, independent life-lengthening effect.


In Conclusion 

Slightly cutting calories may be advantageous in reducing weight, cholesterol, and inflammatory markers.  For many, its not a radical change, but slight adjustment.  Adding in more vegetables, whole grains and fibrous foods will help to increase fiber content, increasing satiety.  Cutting out one snack or late night splurges may be the only adjustment needed to reduce the calories needed to reap some of the potential benefits from the aforementioned studies. 

If this sounds confusing or overwhelming, Registered Dietitian Nutritionists can be the short term guidance you need to make this a lifestyle, and find strategies to include more of the foods that will help you to get the nutrients you need, and cut the calories you don’t, in the most appropriate way possible.

[i] Fontana L, Partridge L, Longo VD. Extending healthy life span — from yeast to humans. Science. 2010; 328: 321-326. DOI: 10.1126/science.1172539
[ii] Kagawa Y. Impact of Westernization on the nutrition of Japanese: changes in physique, cancer, longevity and centenarians. Prev Med. 1978; 7:205-217
[iii] Brandhorst et al., A periodic diet that mimics fasting promotes multi-system regeneration, enhanced cognitive performance, and healthspan. Cell Metabolism. 2015. DOI: 10.1016/j.cmet.2015.05.02
[iv] Levine ME, Suarex JA, Brandhorst S, Balasubramanian P, Cheng C, Madia F, Fontana L, Mirisola MG, Guevara-Aguirre J, Wan J, Passarino G, Kennedy BK, Wei M, Cohen P, Crimmins EM, Longo VD. Low protein intake is associated with a major reduction in IGF-1, cancer, and overall mortality in the 65 and younger but not older population. Cell Metabolism. 2014; 19: 407-417
[v] Fontana L, Meyer TE, Klien A, Holloszy JO. Long-term calorie restriction is highly effective in reducing the risk for atherosclerosis in humans. Proceedings of the National Academy of Sciences. 2004; 101(17): 6659-6663
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