3 Practical Ways to Restrict Calories and Potentially Live Longer

Thursday Jun 11, 2015 | BY |
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Calorie counting chart green apple and tape measure items for a diet

Could significantly reducing your daily caloric intake really help you live longer?

Science is shouting about the benefits of reducing calories.

Could this be something we could take advantage of today?

The biggest study on this to date was published in April 2014.

Researchers fed 76 rhesus monkeys (a primate species considered very similar to humans) a diet containing 30 percent fewer calories than they would normally have eaten, and compared them with a group of similar monkeys who ate all they wanted. (Those on the restricted diet still got all the essential nutrients they needed.)

The results were impressive:

  • The comparison monkeys who ate all they wanted had a 2.9 times increased risk of disease, including diabetes.
  • The comparison monkeys also had a threefold increased risk of death. More specifically, 63 percent of the control animals died during the study period, while only 26 percent of the animals on the restricted diet did.

Many other studies have shown additional health benefits of similar diets—yet so far, most of us don’t relish the idea of reducing our daily calorie intake by 30 percent for the rest of our lives.

Is there anything else we can do that would take advantage of this research?

What is Caloric Restriction?

Caloric restriction (CR), or “dietary restriction” as it’s often called, has been studied for decades in animals. Most studies have shown it to have health benefits, the main one of which seems to be extending life. Results show it to give subjects up to a 40 percent increase in life span.

Simply put, CR is a diet based on low calorie intake. The definition for “low” varies depending on the person, and is usually based on past calorie intake, as well as size, weight, activity, age, etc.

Most of the studies on CR and mortality have been conducted in animals, since they have shorter lifespans and are easier to research in this field. We do have some connections that apply to humans, however. Research on animals has discovered that rhesus monkeys on CR that have experienced increased lifespan benefits have a reduced body temperature and lowered fasting insulin levels. They also have increased levels of the hormone DHEA-S. Results from the Baltimore Longitudinal Study of Aging also suggest that humans who live long have the same sort of biological markers—low body temperatures, low levels of circulating insulin, and high DHEA-S levels.

An older study conducted in the late 1970s also found that healthy seniors receiving about 1,500 calories a day for three years had lowered rates of hospital admissions and death rates.

Currently, the National Institute on Aging (NIA) is studying CR in people—one 250 healthy volunteers ages 25 to 45 are being tested now. Meanwhile, based on current research, here are the benefits of CR as we know them so far:

  1. Helps maintain a healthy weight: Many of our modern diseases are somehow connected to overweight and obesity. Cutting back on calories naturally results in weight loss, as well as reduces visceral (dangerous) body fat, which then helps reduce the risk of weight-related diseases.
  2. Reduces risk of heart disease and diabetes: Eating fewer calories reduces age-related chronic diseases like heart disease, stroke, and cancer. In addition to avoiding the traps of overweight and obesity, simply eating less has been linked with a lower risk of disease. A 2004 study, for example, found that people who ate 10-25 percent fewer calories (about 1,100 to 1,950 calories per day depending on height, weight, and gender) than the average American for 3-15 years drastically reduced their risk of developing diabetes or clogged arteries.
  3. Keeps the brain sharp: A 2014 study found that calorie-reduced diets helped slow the typical changes associated with aging in the brain as related to memory. An earlier 2008 study in senior subjects (mean age 60.5 years) also found that restricting calories significantly improved verbal memory scores and memory performance.
  4. Potentially extends life: There is still debate on whether this would apply to humans, but we have several studies showing that CR could add years to your life. There was the 2014 study on rhesus monkeys mentioned at the beginning of this article. An earlier 2006 study in overweight humans also found that a low-calorie diet led to changes in metabolism and body chemistry that have been linked to better health and longer life.
  5. Boosts the immune system: CR may increase the efficiency of the immune system. A 2004 study noted that animals fed a restricted diet had immune systems superior to those who ate as much as they wanted. Researchers theorize that CR slows down aging processes that affect the immune system, allowing it to stay younger-acting for longer. A 2006 study also showed that limiting calories seemed to boost key infection-fighting cells in the immune system.
  6. Slows the aging process: We have some evidence from studies so far that the process of digesting food generates free radicals, which are linked with aging. Eating less, and allowing our systems to spend less time digesting, may reduce our exposure to free radicals. A 2004 study, for example, found that animals on calorie-restricted diets showed lower levels of free radical damage in their DNA, and lower rates of free radical production. A recent 2015 study also found that caloric restriction helped muscles to avoid damage caused by free radicals and muscle cells to better use antioxidants, helping them to function better.
  7. Reduces risk of cancer: A 2007 study found that CR in healthy individuals was associated with a reduced level of insulin-like growth factor-1 (IGF-1) and cyclooxygenase II (COX-2)—both of which may be protective against cancer. Other studies, for instance, have shown that higher levels of IGF-1 were associated with greater risk of colon, prostate, and breast cancers. COX-2 has also been linked with promoting the spread of cancerous tumors.
How to Apply CR Today

Most of the studies referenced above employed serious caloric restriction, at up to 30 percent of the standard amount of daily calories. Since that’s impractical for most people to maintain for a long period of time, are there other options?

Turns out there are. Here are the main three:

  1. Intermittent fasting: We’ve talked about this before on this site (The Magic of Intermittent Fasting), and have shared the potential health benefits. The idea here is that you occasionally give your body a break by staying off food for 1-3 days. Some people simply skip a meal or two on certain days of the week, which also qualifies. Animal studies have found benefits—in 2003, for example, mice that fasted regularly were healthier in some ways than those on constant CR. They had reduced glucose and insulin levels and increased resistance of neurons in the brain to stress. A 2015 study also found that intermittent fasting in humans (cutting back by 25 percent one day, and eating 175 percent of normal caloric intake the next), increased SIRT 3, a gene that promotes longevity and is involved in protecting cells from damage. It also decreased insulin levels. We don’t have all the answers yet, but research continues—two new studies from Washington University, for example, are looking into intermittent fasting and its potential benefits in humans.
  2. Cut back, but not by so much: Currently, there is no set definition of CR as far as how many calories you have to cut. So cutting back by even about 11 percent may be beneficial, particularly if your goal is to lose weight. A 2006 study, for example, found that humans who cut back on daily calorie intake by about 11 percent for a year experienced significant weight loss and reduced body fat, including dangerous abdominal fat.
  3. Reduce your eating to only 8 hours a day: We talked about this in a previous article (The 8-Hour Diet). Limiting your eating to only eight hours a day is a form of fasting, as you go the other 16 hours without food. It can be the easiest option of the three, and the most likely to create success, which will be a good motivator to continue.

Caution: Please don’t try long-term CR just yet. Some studies have shown that it can have negative side effects, including anemia, muscle wasting, edema, and neurological effects. Until we know more how to manage the idea in humans, it’s best to limit any CR to a few days, at most.

Have you tried restricting your calories at times? Please share any experiences you’ve had with it.

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NYU Langone Medical Center, “Calorie-restricting diets slow aging, study finds,” ScienceDaily, November 17, 2014, http://www.sciencedaily.com/releases/2014/11/141117110650.htm.

Ricki J. Colman, et al., “Caloric restriction reduces age-related and all-cause mortality in rhesus monkeys,” Nature Communications, April 1, 2014; 5:3557, http://www.ncbi.nlm.nih.gov/pubmed/24691430.

Denise Grady, “Low-Calorie Diet May Lead to Longer Life,” New York Times, April 5, 2006, http://www.nytimes.com/2006/04/05/health/05diet.html.

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Ilhem Messaoudi, et al., “Delay of T cell senescence by caloric restriction in aged long-lived nonhuman primates,” PNAS, December 19, 2006; 103(51):19448-19453, http://www.pnas.org/content/103/51/19448.full.pdf.

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Edda Cava, Luigi Fontana, “Will calorie restriction work in humans?” Aging, July 23, 2013, 5(7):507-514, http://www.impactaging.com/papers/v5/n7/full/100581.html.

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Colleen M. Story

Colleen M. Story

Colleen M. Story, a northwest-based writer, editor, and ghostwriter, has been creating non-fiction materials for individuals, corporations, and commercial magazines for over 17 years. She specializes in the health and wellness field, where she writes and ghostwrites books, e-books, blogs, magazine articles, and more.

Colleen is the founder of Writing and Wellness. Her fantasy novel, “Rise of the Sidenah,” was released with Jupiter Gardens Press in September 2015. Her literary novel, “Loreena’s Gift,” is forthcoming in spring 2016 from Dzanc Books. She lives in Idaho. www.colleenmstory.com

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