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Eat Less to Live Longer

Eating less has been shown to provide more health benefits than just weight loss. In fact, Italian researchers discovered that one of the most effective anti-aging methods is limiting calorie intake, also known as calorie restriction. 

According to the Centers for Disease Control, the average American male consumes about 2,745 calories/day and the average female consumes 1,833 calories/day. A limited calorie diet restricts consumption by up to one-third of the average intake.

Calorie restriction has been well-established in animal studies, where the subjects’ diets are well-controlled. In 1935, a Cornell University scientist discovered that rats on a calorie-restricted diet lived nearly 30% longer than those on "normal" diets. Since then, scientists have been testing the impact of a calorie-restricted diet on other animals to further prove their theory.

The effects of calorie restriction are more difficult to duplicate in humans, however. Participants of the Calorie Restriction Society followed an approximate 1,800 kcal/day diet for 15 years. This is approximately 30% fewer calories than their western diet counterparts. They typically consumed higher fiber, more fruits, vegetables and other low glycemic foods such as whole grains. The participants reported lower cholesterol and triglycerides, lower blood pressure, lower fasting blood glucose and insulin levels and lower overall body inflammation. The subjects’ Body Mass Index (BMI) was also on the lower side of normal.

Another trial by the researchers of the National Institute of Aging followed healthy, non-obese men and women, some who were chosen randomly to restrict their diet by 25% and others who could eat what they wanted. The calorie-restricted group was found to have reduced calorie intake by 12% (~300 calories) rather than the prescribed 25%, but still saw a significant reduction from baseline of all measured cardiometabolic risk factors, including LDL cholesterol, total cholesterol and blood pressure.  They also saw significant improvements in C-reactive protein, insulin sensitivity and metabolic syndrome scores as compared to the group who ate what they wanted. Additionally, the calorie-restricted group saw a sustained weight loss of 16.5 pounds. 80% of participants in the calorie-restricted group, who were in the overweight range of body mass index, were normal weight by the end of the trial compared to 27% of the control group who became overweight. Trial subjects also saw positive benefits in their quality of life, including significant improvements in mood, general health, sex drive and sleep. Additionally, unlike more restrictive diet plans where weight can be regained quickly after completing the diet, subjects were able to maintain about 50% of the weight loss two years later, indicative of continuing new eating habits and attitudes after completing the study. They found that cravings for sugary, fatty and other junk foods may decrease after calorie restriction.

Mark Mattson, PhD, chief of the Laboratory of Neurosciences at the National Institute on Aging, explained how a calorie-restricted diet increases life span. "First, it reduces free radical production, or the production of highly damaging forms of oxygen, and the second is that calorie restriction increases the resistance of cells to stress,” he explained. “We think that both of these are important in protecting against a number of different diseases that have a negative impact on life span, such as cardiovascular diseases and cancer."

How to Start
If you're interested in trying calorie restriction, consult with your primary care provider or a dietitian to make sure your diet plan includes proper nutrition and appropriate exercise. They might recommend bloodwork to get a baseline for cholesterol and blood glucose levels so you can track your improvements. 

“Start with moderate changes,” encouraged Mel Hendershott, MS, RDN, CSO, a dietitian at Shaw Cancer Center. “Start by substituting refined carbohydrates for healthy fruits and vegetables.”

Create a support system. Regular visits with a dietitian are recommended, and The Calorie Restriction Society is a helpful resource. 

Mitigate the risks. “One pitfall of calorie restriction is that having a lower body weight can lead to a decrease in bone-mineral density that could put some at risk for osteoporosis,” explained Hendershott. “However, exercising regularly is an effective method for preventing osteoporosis and age-related fractures. Those trying calorie restriction should include a variety of weight-bearing exercises in their routine, including weight training and aerobic activity such as running or walking with weights.”

The underlying premise of calorie restriction, according to the Calorie Restriction Society, is, "to eat fewer calories, while not consuming fewer vitamins, minerals, and other components of a healthy diet, and by doing so achieve a longer and healthier life."

It is also important to ensure you are incorporating sufficient and balanced macro ratios of protein, carbohydrates and fat into your diet.

“We all want to live longer, healthier lives,” explained Hendershott. “Whether you follow a calorie-restricted diet or you mindfully reduce calories, eat healthy foods, exercise regularly and get adequate sleep, taking the steps to improve your health will improve your quality of life and could help you live longer.”