Last updated April 5, 2018 at 12:16 pm
Annoying news for the lean, mean and healthy; it’s still a good idea to watch those calories.
New research from the US suggests that cutting caloric intake by 15 per cent for two years can slow ageing and protect against age-related disease such as Alzheimer’s and Parkinson’s disease, as well as cancer, diabetes and others.
Known as CALERIE (Comprehensive Assessment of the Long-Term Effects of Reducing Intake of Energy), this was the first randomised controlled trial to test the metabolic effects of calorie restriction in non-obese humans.
It found that calorie restriction decreased systemic oxidative stress, which has been tied to age-related neurological conditions.
How calorie restriction cuts disease risk
Lead author Leanne M. Redman, associate professor of Clinical Sciences at Pennington Biomedical Research Center, part of Louisiana State University, says many factors, including antioxidant mechanisms and dietary and biological factors, influence metabolism, but current theories hold that a slower metabolism is most beneficial for healthy ageing and that organisms that burn energy most efficiently should experience the greatest longevity.
This graphical abstract depicts the effects of a 2-year calorie restriction (CR) trial in healthy, non-obese humans, which found evidence that prolonged CR enhances resting energy efficiency, resulting in decreased oxidative damage to tissues and organs. Credit: Redman et al./Cell Metabolism
“The CALERIE trial rejuvenates support for two of the longest-standing theories of human ageing: the slow metabolism ‘rate of living’ theory and the oxidative damage theory,” she said.
The latter ties overproduction of free radicals to oxidative damage to lipids, proteins and DNA, leading to chronic diseases such as atherosclerosis, cancer, diabetes, and rheumatoid arthritis.
The second phase of the study reports results from 53 healthy, non-obese men and women aged 21-50 who cut calories and underwent additional measurements for metabolism and oxidative stress. The calorie reductions were calculated individually through the ratio of isotopes absorbed by the participants’ molecules and tissues over two weeks, a technique that accurately pinpoints a weight-maintenance calorie level.
Those in the calorie restriction group lost an average of almost 9 kg, although they did not follow a particular diet and weight loss was not the study’s goal. No adverse effects, such as anemia, excessive bone loss, or menstrual disorders were noted; in fact, both trials led to improvements in mood and health-related quality of life.
Redman emphasised that CALERIE looked at the effects of calorie restriction on ageing, not weight loss, where discussions of “fast” or “slow” metabolism most often arise. “We know from mammalian studies that the smaller the mammal, the faster their metabolism and the shorter their longevity,” she said.
While the number of participants was relatively small and the duration short in the context of a human lifespan, biomarkers of ageing were improved in study participants.
Next steps include establishing robust biomarkers of human ageing and examining the effects of calorie restriction in conjunction with antioxidant foods or substances like resveratrol, which mimic calorie restriction.
The paper published in Cell Metabolism
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