The second phase of the study shows results from 53 healthy, non-obese men and women who are in the age group of 21 and 50 who have reduced calorie intake by 15 percent over two years and underwent additional measurements for metabolism and oxidative stress.

The reduction in calories was calculated individually through the ratio of isotopes absorbed by the participants' molecules and tissues over two weeks. This is a technique that shows a weight-maintenance calorie level accurately.

Participants who were in the calorie restriction group lost an average of about 9 kg, although they did not follow a particular diet, and weight loss was not the goal of the study.

There were no adverse effects like anemia excessive bone loss, or menstrual disorders. However, both clinical trials showed improvements in mood and health-related quality of life.

Redman said that even people who are already healthy and lean could benefit from a calorie restriction regimen.

In lab animals, calorie restriction was found to lower the core body temperature and resting metabolic rate.

Redman emphasized that CALERIE study only looked at the effects of calorie restriction on aging and not weight loss.

She said that mammalian studies show that when the mammal is smaller, the faster their metabolism and the shorter their longevity would be.

Calorie Restriction Regimen

Many factors like antioxidant mechanisms and dietary and biological factors have a great impact on metabolism, said Redman.

However, current theories reveal that a slower metabolism is even more beneficial for healthy aging and that organisms that burn energy most efficiently need to experience the greatest longevity.

"The CALERIE trial rejuvenates support for two of the longest-standing theories of human aging: the slow metabolism 'rate of living' theory and the oxidative damage theory," she says.

The oxidative damage theory causes overproduction of free radicals to oxidative damage to lipids, proteins, and DNA, leading to chronic diseases including atherosclerosis, cancer, diabetes, and rheumatoid arthritis.

In this study, the number of participants was relatively small, and the duration too was short in the context of a human lifespan. However, biomarkers of aging were improved in the participants of this study.

Further research is required to establish robust biomarkers of human aging and investigating the effects of calorie restriction in combination with antioxidant foods or substances like resveratrol that mimic calorie restriction.

What are Age-related Diseases?

Aging is referred to the accumulation of changes that render a person more vulnerable to death. Chronic diseases and increased mortality are often cited as the hallmark of old age. Some of the common age-related diseases are:

• Cardiovascular diseases
• Diabetes
• Cancer
• Arthritis
• Osteoporosis
• Dementia
• Alzheimer's disease

What is Calorie Restriction?

Calorie restriction is a reduction in calorie intake without deprivation of essential nutrients. A few simple rules can help control your daily portions of food, that help regulate your body weight.

Foods to include in your Diet:

• Nuts, olive oil, fish oils, flax seeds, or avocados
• Fresh fruits are best. Prefer whole fruits rather than juices.
• High-fiber cereals and bread made from whole grains or legumes
• Fish and shellfish, organic chicken or turkey
• High-quality protein such as eggs, beans, low-fat dairy, and unsweetened yogurt

Foods not to be included in your Diet:

• Deep-fried foods
• Packaged and fast foods, especially those which are high in sugar content, baked goods, sweets, chips
• White bread, sugary cereals, refined pasta
• Processed meat and red meat
• Sugary drinks and beverages
• Low-fat products that have replaced fat with added sugar, such as fat-free yogurt

References :

1. NIH study finds calorie restriction lowers some risk factors for age-related diseases - (https://www.nih.gov/news-events/news-releases/nih- study-finds-calorie-restriction-lowers-some-risk-factors-age-related-diseases)
2. Age-Related Diseases - (https://www.omicsonline.org/scholarly/agerelated-diseases-journals-articles-ppts-list.php)
3. Calorie Restriction Explained - (https://www.fightaging.org/archives/2002/11/calorie- restriction-explained/)
4. CRON - Calorie Restriction with Optimal Nutrition - (http://optimal.org/voss/cron_overview.html)

Source: Medindia