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Eat less, live longer?

Calorie restriction regimes - the science behind the claims

Author: Doreen Corbey April 5 2010

We are living in an era where women strive to be the ubiquitous size 0 (UK: size 4). About 5 years ago, most of us didn’t even know this size existed, and prior to watching ‘The Devil Wears Prada’, I thought it was a made-up size for 10-14 year olds, not a real dress size for grown-up women.

It may surprise you therefore to learn that there is a movement which has been gathering momentum over the decades which claims that eating less will help you to live longer. I first came across this about 20 years ago watching a documentary about an experiment in America on a small group of people. The group was really too small to show any proven results but the idea was there.

Much research has been done since the 1930s, mainly comparing a group of calorie restricted animals with a control group of normally-fed ones. The experiments revealed that calorie-restricted mice lived longer and were healthier, more active and more mentally alert than their unrestricted counterparts.

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Back in the 1970s, a research team from Michigan State University headed by E D Schlenker followed the history and diets of 97 women over a period of 24 years. They all started off in middle age and by the end of the research, among those that were still living, the ones who consumed fewer calories were more in number and looked younger!

In 2004 a team from Washington University published their findings after following a group of 36 volunteers between the ages of 35 and 82. Half the group followed a calorie restriction regime for 6 years, while the other half a typical Western diet. At the end of the study, tests proved that the calorie-restricted group had vastly lowered risks for heart disease as well as a lower percentage of body fat. Furthermore, 3 of the low calorie group found their originally high cholesterol levels lowered to the point where they no longer needed medication.

So what is the reason for these results? It is believed that decreasing your calories sends a message to the body that you’re in for some hard times, so it puts itself into self-preservation. Your metabolic rate slows, your temperature drops and ageing occurs at a slower pace.

Of course you have to use common sense and not apply this lesson to growing bodies, ie babies, children or teenagers who are still laying down their bones. Roy Walford, a scientist from UCLA and one of the pioneers of calorie restriction has recommended that you could start at around middle age and still have enough time to extend your lifespan.

The trick to success in calorie restriction is to plan and research thoroughly before starting. Walford found that it is very difficult for humans to follow this regime properly if calorie restriction is introduced quickly. But if it is done gradually over the space of 5-7 years with the end goal of cutting back about 20-25% of what you currently eat, this is more easily achievable. Leslie Kenton in her book Ageless Ageing writes that you can cut back your calorie intake to 60% of what you currently eat, although some people may see this as extreme.

Walford insists that calorie restriction is not like a slimming diet, nor is it starvation. As with the animal experiments, the quality and varied balance of the food is essential. It must be rich in vitamins, minerals and essential fats. All processed food and junk food must go, as whatever you put in your mouth must benefit your health.

Another piece of the puzzle is you then help protect your health by supplementing with potent quality supplements. The supplements should do as their name suggests, that is, supplement your diet – they are not a substitute for high-quality, nutritious food. The essential part of calorie restriction is to ensure that what goes in will nourish you, not just feed you.

Interestingly, some researchers found that intermittent and regular fasting could produce the same results as calorie restriction. The recommendation is to spend a week alternating between fasting (for 2 or 3 days) and normal eating. This is unlike religious fasting where you eat before dawn and after sunset; for the days you fast, you live on water while the remaining days you eat normally. According to research carried out on animals, lifespan was increased by 20-30% and the rate of ageing was slowed.

As with all eating regimes that go against conventional thinking, calorie restriction has its supporters and critics. Extreme calorie restriction is media grabbing, and even moderate restriction is not controversy-proof. In July 2009, scientists at Stanford University suggested that studies showing underfed animals to live longer and healthier lives could not directly apply to humans, because the animal case studies had been living in pristine, clinical conditions and not in the real world. They tested calorie restriction on fruit flies and exposed them to bacteria. The calorie reduced flies, when infected with salmonella, lived twice as long as the normally fed flies, but when infected with listeria, survived 30% fewer days. [1]

Another US team led by Raj and Forster contested the claims of calorie restriction saying that it only extended lifespan if used on obese patients or people who gained weight early on in adulthood. Otherwise, they said that for normally healthy non-overweight people, calorie restriction would show little difference. [2]

There is an ongoing study in America, probably the largest conducted on human subjects, which is following 132 people to examine the effects of calorie restriction by 25% over a 2 year period. Called “Calerie” (Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy), the study has taken individuals who have a normal-to-slightly-overweight BMI. The study provides regular counseling, suggesting how difficult calorie restriction could be for most people. We await the results with interest! [3]

There is plenty of food for thought here and a growing movement on both sides of the Atlantic on this subject. Lisa Walford, daughter of Roy Walford, has written a book called The Longevity Diet. In it she recommends calorie restriction by 13-15% of your baseline level, the baseline being the number of calories needed to keep you at a stable weight, which differs from person to person. She sees anything other than this moderate level as extreme. Sadly, there will always be extreme cases who give notoriety and bad press for the movement.

• The official Roy Walford website
• Calorie Restriction Society website
• Caloric Restriction Optimal Nutrition Society or CRON-ies website

About the Author

Doreen has had a passion for massage since she was 15 years old. She still has that passion, and offers massage, specialist facials and other beauty treatments in her home-based salon in Surrey. With any energy left over she will devour all the beauty pages of all the magazines she can lay her hands on!

Doreen's homepage: Bellessence