The proof that being hungry could help you live longer is strong. It’s been confirmed time and again in high-quality scientific experiments… if you are a fruit fly.

Calorie restriction (CR) probably would extend human lifespans, too, but we really don’t know that for sure. 

To date, CR has been a lifestyle choice. It seems that people who follow it do live longer and stay healthier. But it’s all circumstantial evidence. It could simply be that people who eat fewer calories are also more active or ingest less fatty food or indulge in less red meat.  

Correlations can be chancy. Data also prove that deaths by drowning increase when ice cream sales rise, but as we know, ice cream doesn’t  cause people to drown.

There has never been a controlled experiment where researchers began restricting the calories of dozens of children, kept them on restriction for the rest of their lives, and followed them all the way from cradle to grave. That’s what it would take to prove CR works. There never will be an experiment like that. Most experiments on CR have been too short or followed too few people to make the case strongly. But we are getting a little closer.

Researchers in England did run a short-term controlled experiment that put 456 volunteers in two groups. Half of them ate whatever they wanted. The   CR group was asked to cut calories by 25%. Most failed to keep that up, but they did reduce calories by 12% on average.

At the end of the CALERIE trial, the CR volunteers had much better profiles on heart risk factors. They weighed less. Most lost about 10% of their body weight during the experiment.

They also had lower blood pressure, better blood sugar levels, less insulin resistance, lower cholesterol and blood lipids and less inflammation.

As the ages of these volunteers ran from 21 to 50 during the 2007-2010 experiment, we won’t know who lives longest for several decades yet. [1] But the CR group is definitely ahead so far.

Calorie Restriction Defined

Is this something you could do? First, you would need to set a calorie goal. The English experiment invoked a 25% cut in calories. Some CR believers maintain an extreme diet and only eat 1,000 to 1,200 calories per day. Others approach calorie reduction by intermittent fasting.

Intermittent fasting seems to be the easiest approach for many people. A day of being hungry here and there is better than being hungry all the time. Two popular plans are time restricted eating and the 5:2 plan.

In the first one,  the dieter limits eating to specific hours, say from 7 to 3 or 10 to 6. This cuts bedtime snacking, which may be a reason it seems to be effective.

The other choice is to fast all day for two days, allowing yourself only 500 calories. That’s basically a bowl of soup for lunch and dinner—and not cream of broccoli!

Taking Care

Obviously, cutting calories, while good, can go too far. Anorexia kills. Even among people who recovered from anorexia, the health effects may be forever. Canadian researchers have calculated that girls who were anorexic at age 15 and survived cut 25 years off their expected life span.

But for those of us well above the anorexic level, what about all those studies that show calorie-restricted (CR) diets are linked to living longer? 

There are a lot of us. Roughly 40% of Americans are obese, and 70% of us are at least a little overweight. In fact, people whose weights are “normal” on height-weight charts are actually a minority.  

There are plenty of logical reasons for us to shed pounds. Obesity is highly correlated with some kinds of cancer, diabetes, heart disease, knee and back pains, asthma, sleep apnea, to name just a few nemeses.

Intermittent fasting has been safe for many people. This is not even a new idea. It has been a feature of many world religions for centuries.

If you are interested in doing it right, be careful where you get your information. A good many self-declared experts are handing out advice.

One person who can explain it well, who keeps up with research, and recommends reasonable is Brad Pilon, author of Eat, Stop, Eat. Books by Jason Fung, including the Complete Guide to Fasting, are also good choices. These authors know the science and can help you follow a safe program.

What About Those Long-Living Mice and Bugs

As you know, health procedures and drugs are almost always tested on something else before scientists run experiments on humans.

But there is another source of help that also comes out of research on fasting done with bugs, mice, and other animals.

It has long been held that the nutrient resveratrol, which is found in grapes, blueberries and other food sources, mimics calorie restriction. Some claim it is like fasting without giving up food. That might be overselling it, but resveratrol definitely has shown helpful effects in clinical trials.

Some people believe this calorie restriction mimicry is the reason resveratrol seems to extend human life. Resveratrol has been hailed as the solution to the  “French Paradox”—the odd fact that French people ate more fatty food, smoked, and exercised less and yet have better heart health than Americans? It was the red wine. Specifically the resveratrol in the red wine.

Several experiments on animals have confirmed that calorie restriction and resveratrol are especially effective when done together: 

•  Nematodes (worms) lived longer when their calories were restricted and they were receiving resveratrol at the same time.

•  Another experiment on yeast and flies also showed they lived longer on restricted calories, again results were best when the subjects were fed resveratrol.

•  A new experiment just showed that mice also lived longer when fed only once a day, presumably because that meant they fasted longer as well as receiving fewer calories overall.

So, the good news... Everything we know about CR suggests you could go that route if you want to, and it will very likely do you some good.  

But you could also increase your resveratrol with a supplement, and that may bring similar benefits.

And if you would like to cut calories just a bit and take resveratrol, you could have an idea plan. 

Photo credit: Vanessa Loring