Calorie restriction (CR) is a strategy - a lifestyle choice when practiced by humans - proven to extend healthy and maximum life span in rodents and primates. Some animal studies conducted over the past 20 years have shown up to a 40% increase in maximum life span.
CR also provides numerous secondary health benefits, such as a greatly lowered risk for most degenerative conditions of aging.
Recent studies have demonstrated these same secondary health benefits in humans. Many researchers believe the evidence to date shows the practice of CR will extend the healthy human life span, but consensus has not yet been reached on this topic.
A calorie restriction diet aims to reduce your intake of calories to a level 20-40% lower than is typical, while still obtaining all the necessary nutrients and vitamins. CR is also known as CRON, for "calorie restriction with optimal nutrition." Mild CR may be as easy as adopting a much healthier diet, taking a few supplements and not eating snacks.
The degree to which CR can extend the healthy human life span is open to debate - and is the subject of vigorous discussion within the scientific community - but the evidence for at least some healthy life extension is compelling.
The beneficial effects of CR in laboratory animals have been known for a long time, but only in the past decade - and in particular over the past few years - has more funding and effort been devoted to this field.
The genes and processes that control metabolism are notoriously complex, and scientists do not yet have a complete understanding of the way in which CR fits into the overall picture. But they are working on it.
You may have seen CR mentioned more often and in more detail in the mainstream media of late; the phrase "low-calorie diet" has also seen a lot of usage. To be precise about these terms, calorie restriction is simply the most widespread and well-researched form of low-calorie diet. You can find out more about the science and technical details of calorie restriction here at the
Weight loss should be mentioned in the context of CR, even though it is not the primary goal of a CR diet - if you eat fewer calories, you will slim down. Research indicates that being overweight, or carrying excess body fat, is harmful to your long term health in many different ways. Excess weight increases risk factors for conditions ranging from diabetes to cancer to Alzheimer's, most likely due to the relationship between fat cells and chronic inflammation.
It is no exaggeration to say that if you are overweight, you will have a shorter, less healthy life - many recent studies suggest that even comparatively little excess weight is bad for you over the long term, significantly raising your chances of suffering a range of age-related conditions.
For example, it appears that CR provides a boost to the process of autophagy. Autophagy is the way in which your cells remove damaged components in order to recycle the materials into new replacement parts. Several lines of research indicate specific types of damaged cellular components left to cause problems over time contribute to age-related decline and damage inflicted upon the rest of your body's machinery.
How to get started on CR You'll find a wealth of information and many, many starting points out there, some of which can be quite intimidating to the newcomer. You might find the following path useful:
One thing you'll find out quite early on in your journey into calorie restriction is that you'll have to stop eating a lot of highly processed, rich, modern foods. They are heavy in calories and light in nutritional value. In the US, you can walk into any corner store and eat 1500 Kcal of junk food (chips, chocolate, and so forth) at a cost of $10. You'll be hungry again a few hours later. That same $10 could feed you for two days if you buy vegetables, rice and tofu. You could eat 1500 Kcal a day and hardly be hungry at all.
If you were eating an unhealthy diet before trying this, you'll probably notice the benefits of healthy eating within a few weeks. Your palate will become more sensitive to subtle tastes, you'll need less sleep, feel more alert, and mood swings will be diminished. Much of this stems from cutting processed sugars.
Pay Attention to Calories
Counting calories is a good thing, and it's something that you have to pay attention to. Your body will let you eat far more than is good for you, so your brain is going to have to take over managing the process.
Almost everything you buy from the grocery or supermarket has the calorie content listed on the packet. Note that most manufacturers list calorie content by portion, and that even a lowly bar of chocolate usually has two portions. Marketing departments don't like the number of calories to be too high, as people won't buy it...so they'll just divide the product into more portions with a lower calorie count per portion. Sneaky!
Most foods have more calories than you might think. You can recognize the new practitioners of calorie restriction at the supermarket: they'll be the ones looking at many different product packages and muttering "wow, I had no idea!"
For foods like apples, rice, loose vegetables and so forth, you will need a book of calorie values. Recent editions tend to contain (fairly horrifying) values for fast foods as well as the more usual suspects.
Remember the Supplements
You should always take a good multivitamin supplement (at the very least) when on a calorie restriction diet. In theory, it's perfectly possible to obtain all the vitamins and micronutrients you need from your food. In practice, for most people living busy, working lives, this just isn't going to happen. Remember to take your supplements.
The Water Trick
Doctors tell us that few people in Western societies drink as much water as they should for optimal health, and many people mistake low-level thirst for low-level hunger. A very helpful tactic for those practicing calorie restriction is to drink a glass of water when first feeling hungry. If you are still hungry twenty minutes later, then maybe it's time to think about eating. Half the time, you were just thirsty, however.